Dill, (2015) - Pegmatites y Aplites

Ore Geology Reviews 69 (2015) 417–561

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Ore Geology Reviews j o u r n a l h o m e p a g e : w w w . e l s e v i e r . c o m / l o c a t e / o r e g e o r e v

Review

Pegmatites and aplites: Their genetic and applied ore geology Harald G. Dill Gottfried Wilhelm Leibniz University, Welfengarten 1, D-30167 Hannover, Germany

a r t i c l e

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Article history: history:

Received 24 December 2014 Received in revised form 20 February 2015 Accepted 24 February 2015 Available online 26 February 2015 Keywords:

Pegmatite Economic geology Rare elements Industrial minerals Classi�cation scheme

E-mail address: [email protected] [email protected].. URL: http://www.hgeodill.de http://www.hgeodill.de..

http://dx.doi.org/10.1016/j.oregeorev.2015.02.022 0169-1368/© 2015 Elsevier B.V. All rights reserved.

a b s t r a c t

Pegmatitic rocks are very coarse-grained basement rocks abundant in quartz, feldspar or/and mica, in places, endowed endo wed eith either er wit withh meg megaa cry crysta stals ls of the afor aforemen ementio tioned ned roc rock-fo k-formin rmingg min mineral eralss or rare rare-el -elemen ementt min mineral erals. s. Pegmatites are treated in this study togethe togetherr with with aplitic aplitic rocks, which are composi compositionall tionallyy similar similar to pegmatit pegmatites es but strikingly different from them by their � ne-grained texture. Rocks of the granitic suite take an intermediate positionbetweenthe sit ionbetweenthe twoand, loca locally,they lly,they aretransi aretransitio tionalinto nalinto bot bothh endend-mem member ber typ types, es, emph emphasiz asized ed in the deno denommination inat ion by supp suppleme lementssuch ntssuch as apli aplite te gra granit nitee or pegm pegmatit atitic ic gra granit nite. e. A simi similar lar scen scenariocan ariocan be repo reportedfor rtedfor sye syeniti niticc and, less frequently, for granodioritic through dioritic rocks which are found to be associated in time and space with pegmatites and aplites. The appr approac oachh tak taken en in thecurrentreviewto expl explain ain,, howthe pegm pegmati atitesevolve tesevolvedd thr throughtime oughtime clo closel selyy rese resembl mbles es the way petroleum geologists geologists in search of or during study of a “petroleum system” address this problem. Their “basin analysis” at the beginning is equivalent equivalent to the analysis of the geodynamic setting out of which only three – Varisc Variscan-, an-, AlpineAlpine-and and RiftRift-type type – are con consid sideredin eredin thisstudyas pegm pegmati atite-p te-pron rone. e. Thes Thesee geo geodyna dynamicsetmicsettings have particular “ source rocks” for elements used to be enriched in granites and pegmatites, they provide provide physical regimes capable of sparking the mobilization of �uids and melts and they are endowed with migration pathway path wayss suchas deepdeep-seat seated ed lin lineame eamenta ntary ry rift rifts, s, sha shallowthrustand llowthrustand shea shearr plan planes es used by A- and S-ty S-type pe gran granites ites and pegm pegmatit atites, es, alik alike. e. Pegm Pegmatit atites es sens sensuu stri stricto cto are fou found nd as immi immigrat gration ionss int intoo envi environm ronment entss diff differen erentt fromtheir birthplace where they were trapped in structures providing providing the accommo accommodation dation space necessary for their emplacement and sealed off by impervious roof rocks. In the petroleum system, there are also “oil shows” close to the sour source ce roc rocks ks anal analogo ogous us to the in-s in-situ itu ana anatec tectic tic pegm pegmato atoids. ids. “Oi Oill an andd ga gass see seeps ps” are comp compara arable ble to the vari various ous types of (auto)hydrothermal alteration common to many pegmatite systems. In principle, granites and pegmatites are two sides of the same coin, both are undergoing mobilization and migration; the granite mirrors diffusion and dissemination, the pegmatite re�ects trapping and concentration. Fractionation and separation can be recognized in the petroleum as well as in the pegmatite–granite systems. While the mineralogy of pegmatites has been intensively studied and also backed by experimental work, the (economic) or ore geology of these felsic rocks has not been given adequate attention, particularly when it comess to the clas come classi si�cat cation ion of the pegm pegmati atites. tes. The newl newlyy elab elabora orated ted CMS cla classi ssi�cat cation ion sche scheme me (C hemicalcompohemical composition–M ineral ineral assemblage–S tructural tructural geology geology)) pays pays attention attention to the three ore-con ore-controlli trolling ng facto factors rs of pegmatites pegmatites,, in gene general ral,, and rar raree elem element ent depos deposits its asso associat ciated ed wit withh them, them, in part particul icular ar (Sn–W, Be Be,, RE REE,Zr, E,Zr, Th–U,B,F,P,Li–Cs– Rb, Nb–Ta, Sc, Mo, Bi). The second string to the bow is the wide range of industrial mineral deposits (feldspar, (feldspar, feldspathoids, feldspat hoids, quartz, alumos alumosilicat ilicates es–coru corundum ndum,, garn garnet, et, mic mica, a, grap graphit hite, e, kaol kaolin) in).. The “ore bod bodyy” of the peg pegmati matite te is described by two items—1st order and 2nd order terms, the type of deposit (e.g. metapegmatite, metapegmatite, pegmatoid, pseudopegmatite) pseudopegma tite) and by its shape and structure (e.g., stock-like, tabular, miarolitic). miarolitic). The “ ore composition” is de�ned also by two characteristics, labeled as 3rd order and 4th order terms, by a chemical (e.g. Be–Li–Nb pegmatitestockmat itestock-like like)) and a mine mineral ralogic ogical al qual qualii�er (e.g (e.g.. (and (andalu alusit site) e)–quartz–feldsparmetapegmatitetabular) added to the 1st order and 2nd order terms. The CMS classi�cation scheme as it stands is purely descriptive and designed for genetic and applied economic geology. In terms of structural geology and geodynamic geodynamics, s, pegmatitic deposits primarily occur in ensialic Variscan-type orogens (calc-alkaline) with a thickened crust and a preponderance of thrusting and nappe stacking. In Rifttype sett settings ings (alkaline) (alkaline) wher wheree a stro strong ng subc subcrust rustal al impa impact ct is evid evident ent and as reac reactiv tivated ated/rew /reworke orkedd pseudopegmatites in Alpine-type orogens (calc-alkaline) these deposits developed during the initial stages when the crustal section was still rather thick. Both types pertain to the marginal ensimatic settings. Fullydeveloped ensimatic Andean- and Arc-type settings are devoid of p egmatit egmatitic ic deposits. There are metals in rare element pegmatites that are typical of Variscan-type, Variscan-type, such as U, B, P and Sn. Th, REE, Mo and Zr preferably show sho w up in Rif Rift-ty t-type pe sett settingswherea ingswhereass Li and Ta are of wid widespr espread ead occ occurr urrencein encein reac reactiv tivatedAlpineatedAlpine-typ typee oro orogen gens. s.

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H.G. Dill / Ore Geology Reviews 69 (2015) 417 –561

The highest economic potential has been observed in pegmatites/aplites sensu stricto, pseudopegmatites and pegmatite–skarns. Granite pegmatites pegmatites are ranked second in the abundance of rare elements, mainly Sn and W, whereas metapegmatites and pegmatoids are used to concentrate only feldspar, quartz and mica. A simi similar lar trip triparti artite te subd subdivi ivisio sionn as perf perform ormed ed for the geo geodyn dynamicpositi amicpositioni oning ng of the hostenviro hostenvironmen nmentt can alsobe done for the emplacement of pegmatites themselves. They are part of the (1) thrustbound and fold-related metamorphogenic deposits, (2) collision and intrusive-related deposits and (3) deposits originated from deepseated lineamentary remobilization. With this in mind a direct correlation of pegmatite deposits with nonpegmati pegm atitic tic depo deposit sitss suchas car carbona bonatit tites es or skar skarnn depo depositscan sitscan easi easily ly be perf perform ormed ed and all phys physico ico-che -chemic mical al processes inherent to these groups of non-pegmatitic deposits can be applied to pegmatitic deposits as well. Based upon this joint chemical chemical–mineralogical–geolog geological ical approach approach taken in the classi�cat cation ion of pegm pegmatit atites es it beco becomes mes evide ev identthat ntthat peg pegmat matite itess canno lo long nger er be ref referr erred ed to as a sim simpleprod pleproductof uctof fr frac acti tion onat atio ionn ofa par parent ental al gr gran anitebut itebut have to be placed as an entity of its own hierarchically besides the granite suite. Pegmatitic rocks cannot be put into a category sharply delimited from the adjacent ones. In nature they are often transitional from simple pegmatoids in migmatites to complex pegmatites sensu stricto. They are characterized by a polyphase development with their formation formation guided by structures, contro controlled lled by open access to crustal and subcrustal subcrustal heat and element sources. Since pegmatites and aplites used to be smaller in size than granites, a more consequent concen con centra tratio tionn of elem elementsaccom entsaccompan panied ied by a moreintens moreintensiveinterac iveinteractio tionn wit withh thei theirr coun country try roc rocks ks tak takes es plac placee during their emplacement than in granites (skarn, episyenites, and albitites). Consider Cons ideringthe ingthe econ economicpart omicpart of pegm pegmatit atites, es, the pri primarypegmat marypegmatite ite depo deposit sitss and thei theirr cla clasticapron sticapronss wit withh pla placer cer deposits from residual to �uvial type will be left unchallenged as far as the exploitation of colored gemstones is concerned, because there is no other choice. The hard rock deposits will still have a say when the requirements for the raw material are very strict (ultra-high quartz) or a shortage of electronic and strategic elements is looming (Ta, Nb, Be). B e). Exploitation of industrial minerals from hardrocks is competitive if no easy-to access deposits (near-surface sedimentary deposits) of similar quality are close-by and the labor costs are moderate in the country country of producti production. on. Low-gr Low-grade ade large tonnag tonnagee deposits deposits (salars (salars,, brines) brines) are a challenge challenge particul particularly arly for lithium. The pegmatites pegmatites will maintain maintaintheir their positio positionn as a source source for those those elements elements which which make up the lion lion share in the mineral association, quartz and feldspar. Pegmatites fueled from subcrustal sources, and related in time and space with reactive country rocks (ultrabasic, basic igneous rocks and carbonate rocks) have not yet been given the attention they might deserve. © 2015 Elsevier B.V. All rights reserved.

Contents

1. 2. 3.

4.

Introduct Introd uctio ionn — from experimental work to �eld geology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . The geodynamic setting of pegmatites . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.1. The European Variscides . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.2. The Proterozoic Orogenies of Gondwana . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Thee cl Th clas assi si�cation schemes of pegmatites — complexity and applicability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.1. The his history tory of cla classi ssi�cation of pegmatites . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.2.. Th 3.2 Thee CMS cl class assii�cation scheme of pegmatitic and aplitic rocks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.2.1. Crystal Crystallizati lization on versus deformat deformation ion — ag agee of pe peggma mati titi tizzat atio ionn re rela lati tive ve to th thee ag agee of ho host st ro roccks . . . . . . . . . . . . . . . . . . 3.2.2. Shape and structure of pegmatites . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.2.3. Chemical and mineralogical composition of pegmatites . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Commodities and the origin of pegmatites . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.1. Tin- and tungsten pegmatit pegmatites es and pegmati pegmatite te–skarns (12 DE) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.1. 1 .1. 1 . Sn–W plutonic pegmatites in the Variscan Metallotect . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.1. 1 .2. 2 . Sn–W peg egma mati tittes in the Neo eopr proote tero rozzoic Met etal allo lottec ectt in Af Afrric icaa . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.1. 1 .3. 3 . Sn–W pl plut utooni nicc pe pegm gmat atit ites es of th thee Ne Neoopr proote tero rozo zoic ic Ro Rond ndôn ôniia Pr Proovi vinc nce, e, Br Braz azil il . . . . . . . . . . . . . . . . . . . . . . . . . . 4.1. 1 .4. 4 . Sn–W peg egma mati tittes of the Ne Neoopro rotter eroz ozooic Ol Olde derr Gra rani nittes es,, Nig iger eria ia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.1.5. 4.1 .5. Sy Syno nops psis is of Sn–W pegmatites . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.2. Beryllium pegmatites (14 ABDEJ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.2.1. Be pegmatites in the Variscan Metallotect . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.2.2. Be pegmatites in the Alpine Metallotect . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.2.3. Be pegmatites in the Proterozoic Metallotect in Africa . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.2.4. Synopsis of Be pegmatites . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.3. Rare-ea Rare-earth rth element and zircon zirconium ium pegmatit pegmatites es and pegmatit pegmatitee–skarns (24DE + 39 E) . . . . . . . . . . . . . . . . . . . . . . . . . 4.3.1. REE pegmatites in the Variscan Metallotect . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.3.2. REE pegmatites in the Alpine Metallotect . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.3.3. REE pegmatites in Greenland and Scandinavia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.3.4. REE pegmatites in the Proterozoic Metallotect in Africa . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.3.5. REE pegmatites in the Brazilian Shield . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.3.6. Zr pegmatites . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.3.7. Synopsis of REE and Zr pegmatites . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.4. 4. 4. Ur Uran aniu ium m–thorium pegmatites and pegmatite–skarns (24 DE + 26 DE) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.4.1. U–Th plutonic pegmatites in the Variscan Metallotect . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.4.2. U–Th pegmatites in the Pro rotterozoic Met etaallotect in Africa . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.4.3. U–Th pegmatites in South and North America . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.4.4. 4.4 .4. Sy Syno nops psis is of U–Th pegmatites . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5. Fluorine Fluorine-boron -boron pegmatit pegmatites es and pegmati pegmatite te–skarns (32 DE + 30 D) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.5. 4.

420 425 425 427 429 429 433 4344 43 436 439 445 445 4455 44 4511 45 4522 45 4599 45 460 462 463 469 470 471 472 472 473 473 4733 47 474 474 474 475 4755 47 475 476 476 477


5.

6.

7.

4.5.1. F–B pegmatites in the Variscan metallotect . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.5.2. F–B pe peggma mati tite tess in th thee Pr Proote tero rozo zoic ic me meta tall llot otec ectt in Afr fric icaa an andd So Sout uthh Am Amer eric icaa . . . . . . . . . . . . . . . . . . . . . . . . . . 4.5.3. 4.5 .3. Sy Syno nopsi psiss of F–B pegmatites . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.6. Phospha Phosphate te pegmati pegmatites tes and pegmatit pegmatitee–skarns (38 D) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.6.1. P pegmatites in the Variscan Metallotect . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.6.2. Phosphate peg egm matites reactivated in the Alpine Fold Belt . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.6. 4. 6.3. 3. Ph Phos osph phat atee pe pegm gmat atit ites es in th thee Pr Prot oter eroz ozoi oicc Me Meta tall llot otec ectt in Af Afri rica ca an andd So Sout uthh Am Amer eric icaa . . . . . . . . . . . . . . . . . . . . . . . 4.6.4. Synopsis of P pegmatites . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.7. 4. 7. Li Lith thiu ium m–cesium–rubidium pegmatites (15 D) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.7.1. Li pegmatites in the Variscan Metallotect . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.7.2. Li pegmatites in the Alpine Metallotect . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.7. 4. 7.3. 3. Li pe peggma mati tite tess in th thee Pre reca camb mbri rian an,, Pa Pale leoz ozooic an andd Me Meso sozo zoic ic me meta tall lloote tect ctss . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.7.4. Synopsis of Li pegmatites . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.8. 4. 8. Ni Niob obiu ium m–tantalum–scandium pegmatites (13 DE) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.8.1. Nb/Ta pegmatites in the Variscan metallotect . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.8.2. Nb/Ta pegmatites in the Precambrian Metallotect . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.8.3. Sc pegmatites . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.8.4. 4.8 .4. Sy Syno nopsi psiss of Nb–Ta pegmatites . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.9. 4. 9. Ar Arse seni nicc–bismuth–zinc–molybden enuum pegmatites and pegmatite skarns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.9.1. As pegmatites (21 D) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.9.2. Bi pegmatites (18 D) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.9.3. Zn pegmatites (16 D) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.9.4. Mo pegmatites (11 D) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.9.5. 4.9 .5. Che Chemic mical al qu qual alii�ers in the classi�cation of pegmatites . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.10. Feldspar pegmatites and pegmatite skarns (41 D) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.10.1. Feldspar granitic and syenitic pegmatites . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.10.2. Feldspar pegmatoids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.10.3. Feldspar metapegmatites . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.10.4. Feldspar pegmatites and aplites sensu stricto . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.10.5 .5.. Peg egm matitic ro roccks with semiprecious feldspar varieties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.11. Quartz pegmatites (40 D) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.12. Feldspathoid pegmatites and pegmatite skarns (4 (422 D + 43 D) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.12.1. Scapolite pegmatoid-(skarn) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.12.2. Nepheline and sodalite syenite pegmatites . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.12.3. Zeolite pegmatites . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.13 4. 13.. Al Alum umos osil iliica cate te an andd cor orun undu dum m pe peggma mati tite tess an andd pe pegm gmat atit itee sk skar arns ns (4 (499 ACD + 50 ACD CD)) . . . . . . . . . . . . . . . . . . . . . . . . . 4.13.1. Alumosilicate pegmatites . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.13.2. Corundum pegmatites . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.14. Garnet pegmatites and pegmatite skarn (47 D) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.15. Mica pegmatites and pegmatite skarn (59 D) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.16. Graphite pegmatites and pegmatite skarns (52 D) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.17. Kaolin in pegmatites (55 DH) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Processes in the exocontact of peg egm matites and within pegmatites . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.1. Skarn mineralization and contact metamorphism . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.2. Episyenitization and albitization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.3. 3 . Met etam amoorp rphhogen enic ic,, magmat atog ogen eniic an andd hy hydr droothe herrma mall peg egm matit itic ic pr prooce cessses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Mineral deposits associated with pegmatitic rocks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.1. Variscan-type metallogenic setting and pegmatites . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.2. Rift-type metallogenic setting and pegmatites . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.3. Alpine-type metallogenic setting and pegmatites . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Economic geology of pegmatitee-rrel elaated elements and minerals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.1. Tin–tungsten . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.1.1. Tin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.1.2. Tungsten . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.2. Beryllium . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.3. Rare earth elements and zirconium . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.4. 7. 4. Ur Uran aniu ium m–thorium . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.5. 7. 5. Fl Fluo uori rine ne–boron . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.5.1. Fluorine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.5.2. Boron . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.6. Phosphorus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.7. 7. 7. Li Lith thiu ium m–cesium–rubidium . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.8. 7. 8. Ni Niob obiu ium m–tantalum–scandium . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.9. 7. 9. Ar Arse seni nicc–bismuth–zinc–molybdenum . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.10. Feldspar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.11. Quartz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.12. Feldspathoid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.13. Alumosilicate and corundum . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.14. Garnet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.15. Mica . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.16. Graphite . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.17. Kaolin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

419

478 478 478 480 480 480 487 4877 48 488 490 491 494 4966 49 501 502 502 506 509 510 511 512 513 514 514 514 514 515 515 516 516 516 517 518 518 519 519 5199 51 520 521 522 523 523 524 525 525 525 5277 52 529 529 530 530 531 531 531 532 532 532 533 533 533 533 534 534 534 535 535 535 535 535 536 536 536 536

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8.

Structural geology of pegmatites . . . . . . . . . . . . . . . . . . . . . . . 8.1. Pegmatites and the architectural elements of the country rocks . . . . . 8.2. Plutonic pegmatites and the architectural elements of their country rocks . 8.3 . Pseudopegmatites and the architectural elements of their country rocks . 9. Genetic and economic conclusions and outlook . . . . . . . . . . . . . . . . 9.1. Genetic conclusions . . . . . . . . . . . . . . . . . . . . . . . . . 9.2. Economic outlook . . . . . . . . . . . . . . . . . . . . . . . . . . Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1. Introduction — from experimental work to �eld geology

Pegmatitic rocks are very coarse-grained crystalline rocks which, in places, contain giant crystals of feldspar, quartz or mica that render this felsic lithology to strongly contrast with compositionally similar granitesoften lying in their close vicinity. Thesefeatures drawthe attention of entrepreneurs, mining engineers and mineral enthusiasts to these accumulations of industrial and rare minerals. On the opposite end of the grain-size scale of these crystalline felsic rocks, we may � nd the aplites to be quite similar by chemistry and mineralogy to the pegmatites and granites which they often gradually pass into via aplite granites. In the classical Hagendorf-North pegmatite deposit, SE Germany, a diamond drill hole sunken into the contact zone, displays such a gradual transition from the gneissic country rocks, via the aplitic feldspar rim into the feldspar pegmatite ore (Fig. 1). De �nition: The term “ ore” is de �ned in the current study to describe a concentration of non-metallic, e.g., feldspar, or metallic minerals, e.g. spodumene, in pegmatitic rocks irrespective of its structure and position in the deposit which was or is currently mined for a pro �t. Minerals of showcase quality or of scienti �c purposes only, sometimes only to be detected under the stereomicroscope are omitted from this paper. The reader is referred to one of the several mineralogical papers mentioned in the “ References” or in full-color magazines devoted to mineral enthusiasts. For the Hagendorf –Pleystein Pegmatite Province, the mineralogical part has been compiled in Dill (2015). To elucidate the structural elements and lithology of a stock-like zoned feldspar pegmatite the (Nb –Li–P)–quartz– feldspar pegmatite (columbite–Li–Fe–Mn phosphate) at Hagendorf-North, Germany, hasbeen taken reference (Fig. 1a, b).It is shown in a cross section (Fig.1a, b); by examination of one of its diamond drill cores (Fig. 1c, d)and by visual inspection of hand specimens typical of the various lithological zones (Fig. 1d). Metapegmatite/-aplite: Prekinematic/premetamorphous rocks composed mainly of feldspar, quartz and mica only ( “ barren pegmatitic rocks” ) showing microstructural, textural and mineralogical changes. Gradual transition into augen- and orthogneisses is common. Dynamometamorphic processeshave a deleterious effecton therock-formingminerals and inevitably result in a comminution of feldspar. Thecontact to thewall rocks may be sharp or transitional. Pegmatoids/aploids: Syn- to late kinematic felsic rocks similar in com position to the aforementioned metapegmatites/-aplites. No relation to plutonic rocks in high-grade regionally metamorphosed rocks. Gradual transition into granitoids, but mostly in sharp contact to the metamorphic wall rocks. Crystal growth of feldspar, quartz and mica, although falling short of the size requirements of pegmatites may allow for their use as raw material for ceramic purposes. Seldom rare metals are recorded from these rocks at an economic level. Re �ec t in-situ formation or shortdistance migration of substance. Pseudopegmatites: Pegmatite-like mobilizates, also called remobilized pegmatites or reworked/reactivated pegmatites, which, in places, may have lost their original pegmatitic or aplitic texture but based on their mineral associationand chemical composition point to a pegmatitic derivation. No connection to plutonic rocks can be determined and often found along shear- and thrust zones. They are feasible as deposits for ceramic raw materials and for their rare metal contents.

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537 537 537 537 538 539 540 540 540

Apart from the size of their crystals, it is the varied spectrum of rare elements,e.g., Nb, Ta,Be or Li and theplethora of extraordinary minerals resultant from these elements, that renders these crystalline rocks so different from granitic rocks and draws the attention of mineralogists and mineral collectors, alike, to these felsic rocks. Not surprisingly, numerous mineralogicaland chemical studies have been centered on these pegmatitic rocks, looking at these crystalline rocks from different angles. A great deal of effort has been taken on these minerals to � nd new minerals, re�ning the crystal structure of characteristic minerals and � ne-tuning the physical–chemical regime of formation (Strunz, 1954a,b, 1956; Seeliger and Mücke, 1970; Moore and Kampf, 1977; Sturman et al., 1981; Mücke, 1983, 1988; Marzoni Fecia Di Cossato et al., 1989; Walter et al., 1990; Birch et al., 1995, 2011; Adiwidjana et al., 1999; Raade et al., 2002; Brugger et al., 2011; Yakovenchuk et al., 2012). Others have addressed the mineral textures (Klementova, and Rieder, 2004) and placed emphasis on the chemistry of pegmatites (Černy, 1992;Wiseand Černý, 1996; Černý et al., 1995; Lu and Lottermoser, 1997; Bakker and Elburg, 2006; Oyarzábal et al., 2009). Only a small fraction of the numerous publications can be cited here, mainly from Central Europe. Further papers are in the list of references and in the text, provided that they contain alsosome information on the geology of pegmatites. The latter is often treated like an afterthought and publications are rather scant and mentioned in the text in the pertinent sections. The history of studyingpegmatites is as long as the number of scienti�c papers on pegmatites is big and it is most conveniently recorded by the theories and models used to account for the genesis of pegmatites. The most recent papers citing some previous investigations and summarizing the state-of-the-art of mineralogical research on pegmatites or, in other words, the mindset of their advocates have been published by Černý et al. (2005) and by London (2008). Granitic pegmatites, as they were called by the above authors, developed by late-stage crystallization of a highly fractionated melt deriving from partial melting of crustal or mantle rocks. The siliceous meltseparated fromparentalgranites by �lterpressing which expelled this residual magma so as to become a melt selfintrusive into the country rocks where it gave rise to a wide range of unzoned or zoned pegmatites. It has been Jahns (1955), who put forward that all pegmatitic structures can be accounted for by crystallization from a melt of low viscosity. This explanation has not lost its relevance today. Increasing contents of �uxing agents such as F, Li, Be, P, and H2O signi�cantly reduce the viscosity and solidus temperature of the magma and so provoke concentration of rare or large-ionlithophile elements (LILE) in the residual melt. Cameron et al. (1949) tried to explain the increasing chemical fractionation and inwarddirected textures of the pegmatites. The effects of liquidus undercooling are said to play an important factor and to have dominated the textures of the contact zone of pegmatites characterized by an aplitic rim while in the more central parts it became the cause for the graphic intergrowths and mega crystals to form (Fenn, 1986; London, 2008). The theory was revitalized by London (2008), who assumed undercooled conditions of approximately 200 °C as a special state in hydrous granitic liquids. He also reiterated the viscosityof the growth medium to be important for the particular graphic intergrowth and provided graphs

421


a)

S

N

drill hole (2011) main shaft (1928-1937)

11 m

17 m 22 m

28 m

0

44 m

Gneiss aplitic

Pegmatite with aplitic margin

Granite passing into aplite granite (marginal zone)

Quartz core

30m

20

10

Phosphate zone

b) µSv/h 0.20

0.15 K: 90 cps 0.10 K: 40 cps

U: 70 cps

0.05

U: 30 cps Th: 20 cps

0

Th: 20 cps

S

N

11 m

?

? 0

10

20

30m

Fig. 1. a. Cross sectionthrough theHagendorf-Northpegmatite,SE Germany. Theunderground workingsare shown by the galleries andshafts andrises. Thepegmatite is well zoned and

typical of a stock-like pegmatite body with gneissic country rocks, aplitic internal contact/rim zone, feldspar rim and a quartz core. The rare metal concentration is marked by the phosphatezone inblack(modi�ed from Dilletal.,2013). b. Thecontours of theopenpit havebeengivenin this cross sectiontogetherwitha gamma-surveyacrossthe pegmatite depositwhich gives an ideaof the shape and dip of the pegmatite body at depth (for moredetails see alsoFig. 1a). The gammareadout is given in μ Sv/h and cps (modi�ed from Dill et al., 2013). c. Drill core through theexternalpartsof theHagendorf-NorthPegmatite. Forthe position ofthe drill site seeFig. 1a.The DDHdisplaysthe transitionfromthe Quaternary soilandsoli�uction zone through the saprolite and saprock into the unaltered pegmatite, which is represented by the aplite/aplite granite–pegmatite transition. The gneiss is overprinted by the most recent weathering and pedological processes. The photographs have been provided by the Wasserwirtschaftsamt Weiden/Water authority Weiden. The interpretation of the lithology has been performed by the author. Technical services: DDH drilling by Fa. Eder Brunnenbau Deutschland GmbH and Ingenieurbüro GolHo. d. Drill core through the external parts of the Hagendorf-North Pegmatite. For the position of the drill site see Fig. 1a. Specimens typical of the gneissic wall rocks, aplitic rim zone, pegmatite and phosphate zone.

422


c)

k c o r p a s o t n i g n i d a r g e t i l o r p a s d e r e h t a e w y l p e e D

e e r c s l a i c a l g i r e p + l i o s n w o r B

n i l o a k h t i w e t i l o r p a s d e r e h t a e w y l p e e D

0-1 m

o t n i l a n o i t i s n a r t , e i d t t e r a e t l m a g e e p t i l e p h a t – e t i n a r g e t i l p A

o t d e r n e i t l l a o a e k t i h l i p t a w – k e c t i o n r p a r a g s e t i l p A

e t i t a m g e p r a p s d l e F

3-4 m

2-3 m Fig. 1 (continued).

illustrating the crystal-nucleation delay. It has to be mentioned, that this idea caused a lot of debate and is considered as a misleading pathway by some researchers dealing with the physical–chemical regime of pegmatites. Thomas (2009), Thomas et al. (2008), and Thomas et al. (2009a) showed that the formationof pegmatites is characterized by a combination of metasomatic reactions, and magmatic crystallization from extreme water-rich silicate melts. Pegmatite-forming melts are not in the equilibrium with the parental intrusion, and granite and pegmatite are decoupled at a physicochemical level. Liquidus undercooling forming the basis of London's theory (2008) to explain how the pegmatites came into existence, thus cannot be the driving force according to these authors cited above. For further in formation on this topic that cannot be discussed in a profound way in a reviewon oregeology, the reader is referred to the most recent discussion and reply (London, 2014; Thomas and Davidson, 2015).

Jahns and Burnham (1969) created a model on the basis of experimental studies to explain the derivation and crystallization of granitic pegmatites which formed by equilibrium crystallization of coexisting granitic melt and hydrous � uids slightly below the hydrous granite liquidus. This chemically driven and mineralogically-

minded approach has been taken still today as demonstratedby publications of London et al. (1989), Webber et al. (1999), and Simmons et al. (2003). Pegmatites have a 3-dimensional representation in nature and they were emplacedin relation to theaccommodation space provided by the geological processes being relatedin time andspace to structural disturbances, as part of an orogeny andlast but notleastthe geodynamic evolution of a crustal rock slap and its underlying subcrustal part. Ignoring geological parameters becomes a stumbling block for a real progress in the understanding of the origin and emplacement of pegmatites and the more hides the scope of economic geology. Economic geologyis a “mixtumcompositum” of allgeoscienti�c disciplines focused on onegoal, �nding new mineraldepositsand enhancing the exploitation of existing ones. The keystones of this “mixtum compositum ” are geology and mineralogy whose studies are centered on the emplacement of the ore body and the development of its minerals and rocks (Dill, 2010). To provide a realistic model of pegmatitic mineralization in accordance with nature is impeded by the refusal of alternative ideas for the formation of rare-element granites by anatexis

423


s s i e n g c i t i l p A

agn

gn e t i l p a c i t i n a r g e h t o t e s o l c e t i l p a e t i t a m g e p d e m r o f e D

Agn = aplitic gneiss Gn = biotite gneiss

8 cm

6 cm bt+ch

) e t i n a r g ( e t i l p A bt = biotite ch= chlorite

7 cm qz

kf

e r o c z t r a u q – e t i t a m g e P

qz = quartz, kf = K feldspar

5 cm

10-11 m

Fe-Mn zwieselite (phosphate zone ) Li triphylite Fig. 1 (continued).

or �uid-induced overprintingof barren pegmatites and to discredit them as “untested” and “speculative” (Černy, 1992; Černý et al., 2005). Moreover tectonic correlation with geochemistry has been held to be of minor importance relative to the control by source lithologies (Černy, 1992; Černý et al., 2005). Browsing the pertinent Anglo-Saxon literature, the geology of pegmatites and the geodynamic setting have not widely found application in modeling the e mplacement of pegmatites or have been well entrenched in the literature. Only Martin and De Vito (2005) made an attempt in a key paper to correlate the

tectonic setting with the family-classi�cation scheme of pegmatites, but the paper did not spawn further studies among pegmatologists, despite the fact that a fundamental book covering pegmatites worldwide has already been issued by Schneiderhöhn in 1961, butin a language different from English. Geology and geochronology cannot be cast aside when dealing with pegmatites. As deep geology plays an important part during the emplacement of pegmatites, and super-deep drill holes are less frequently drilled in the crystalline basement than in a hydrocarbon prone basin,

424


the involvement of geophysicalmethods is a must as it comes to the interpretation of a pegmatite-prone crustal section. In an area along the western edge of the Bohemian Massif, close to the Czech–German border, the Hagendorf –Pleystein Pegmatite Province was used as some sort of a test-site for the emplacement of

pegmatitic and aplitic rocks in an ensialic orogen (Dill, 2015). The mineralogical and chemical composition of more than 100 pegmatites all across Central Europe has been studied, thelargestof which in this mineralized region, named Hagendorf-South, totals 4.4 million t of pegmatitic ore, feldspar, quartz and Li phosphate (Forster et al., 1967). The

a)

FichtelgebirgeErzgebirge Sudetes

Cornubian ore field

Amorican Prov.

Central Bohemian+ Moravian Z.

Central Massif Prov.

W Carpathian NE Bavarian Prov.+HPPP Iberian Province

East Alpine

Pyrenees

Bohemian Massif Hagendorf-Pleystein Pegmatite Province (size not to scale)

b)

New England Province

Fig. 2. a. Variscan massifs in Europe with sutures and lineamentary faults bounding the geodynamic units ( Matte et al., 1990; Franke et al., 1995; McKerrow et al., 2000). The map was

supplemented with mineralized provinces containing pegmatite-hosted deposits. Variscan Provinces (yellow), Alpine reactivated-Variscan Provinces (blue). b. The Variscan and the Alleghanian Orogenies on the northern hemisphere and their reactivation along their southern boundary. The North American analogue to the Variscan provinces is highlighted by the New England Pegmatite Province. The Bohemian Massif and the Hagendorf –Pleystein Pegmatite Province often referred to in the text is shown in this sketch map. The size of both is exaggerated.


study was supplemented by extensive geological and geochronological work and backed by data derivedfromgravimetric,geomagnetic, re�ection seismic surveys, and geoelectric deep-sounding on a regional scale. Foot-borne surface as well as underground radiometric surveys were conducted on a local scale. Experimental work has not been done by myself during the project, yet the data that have been published so far in the literature have been placed much emphasis upon and they formed an integralpart of the study for constrainingthe physical–chemical conditions under which the various mineralsformed in the different types of pegmatites, aplites and their host rocks. In the current paper, this study launched in the CentralEuropean test site at Hagendorf –Pleystein or on a larger scale along the western edge of the Bohemian Massif is expanded further a�eld to a wider range of pegmatites worldwide (Figs. 2a, b, 3). This review is based upon the existing literature on pegmatites with special reference given to the geology of pegmatites and aimed at assisting proponents of the genetic and applied branches of economic geology. Mineralogy and chemistry are applied in a well-balanced way so as to underscore this geological study, but not given priority as the title of this review reveals. Emphasis is placed on these geosciences in Dill (2015). 2. The geodynamic setting of pegmatites

In the current paper it would impossible to provide a full blown picture of pegmatites across the globe, many of which are located in remote areasandpoorlystudied,particularlyas tothepartsrelevantto theunderstanding of pegmatites. Therefore emphasis has been placed upon the pegmatite geology of two crustal sections,the Paleozoic Variscan Orogen, extending across the Atlantic Ocean into the Alleghanian Orogen, on the northern hemisphere and the geology of southern Africa and western South America which formedpart of thePrecambrian Continent of Gondwana (Figs. 2a,b, 3). Other areas in Northern America with Greenland, in Australia,in SE Asia andin Scandinaviahave only been addressedto interpret special types and the geology has only been described to the extent necessary for the understanding of the origin of these pegmatites. This is also the case with the Alpine-Carpathian Mountain Range in Europe which cannot be cast aside in a review of the geological evolution of

425

pegmatites as it comes to reactivated ones along with the Mesozoic –Cenozoic amalgamationof the Europeancontinent(Fig.2a). Togive anoverview of the regional geology of all these areas would go far beyond the scope of this paper and it is not given in this review so as not to deviate the reader from the pegmatites and those who want to know more about the geological setting are, hence, referred to the literature cited in the pertinent section or subsection. The Paleozoic European–American pegmatite provinces and the Precambrian Afro-American province are most appropriate to demonstrate the effect of crustal and subcrustal geological processes on the emplacement and the alteration of pegmatites and the positioningof pegmatites in relationto the geodynamic evolution of the crust. 2.1. The European Variscides

The European Variscides, also called Hercynian Fold Belt in the literature extend for over 3000 km from the northern tip of Morocco at the NWtipof Africato the BohemianMassif and reach a width ofas much as 800 km (Matte, 1986, 1991) (Fig. 2a). The present investigations reveal that its southern boundary was obliteratedand part of theVariscan rocks was integrated into theAlpine orogeny whose morphologicalexpression is the Alpine Mountain Range and the Carpathian Mountains within the Alpine-Himalayan Fold Belt (Fig. 2a, b). In Fig. 2a the primary and reactivated pegmatites are shown in yellowand blue.Newly formedpegmatites near theInsubrian and Ivrea Line in the Western Alpine Mountain Range that originated during the Alpine orogeny have been omitted from the map owing to their rather small size and to avoid overload it. They are addressed in this review in Section 4.3.2. This is also true for the pegmatite, e.g., on theIsleof Elba. Both areas were mainly investigated fortheir mineral assemblages and only referred to in the text. The Variscan orogen has been subdivided into different geodynamic units starting off in the foreland with the Rheno-Hercynian Zone and ending in the central part called Moldanubian Zone all of which are highlighted in the sketch map of Fig. 2a. Towards the west, across the modern Atlantic Ocean this orogen passes into the Alleghanian Orogen, now exposed at the eastern coast of the USA and Canada (Fig. 2b). The

Fig. 3. The plate assembly of Gondwana in relation to the continents of today ( Kusky et al., 2003).

426


Table 1

Classi�cation scheme of pegmatitic and aplitic rocks for applied and genetic economic geology.

Fig. 4. a. Quartz–feldspar metapegmatite intercalatedinto biotite–sillimanite gneisses (contact stippled yellow line) exposed in an open pit near Erbendorf, SE Germany. Fracturing along

with the Variscan deformation during the Paleozoic is accentuated by blue lines. b. Close-up view of a � asered quartz–feldspar metapegmatite (albite–oligoclase) near Neustadt a. d. Waldnaab,SE Germany. c. For comparisonof a porphyroblastic �asered augengneiss (orthogneiss/metagranite) (og) in contact with an apliticmobilizate (ap) McKile Gneiss of theDevonian Lost LakePluton, easternCanada. d. Graphic intergrowth of alkalinefeldspar andquartz in thefeldspar metapegmatitetabular mined at GetrudeMine nearWendersreuth, Germany. The yellow arrowhead denotes a transition from a graphic intergrowth with the preexisting orientation of the rock-forming minerals still preserved into a graphic intergrowth with tectosilicates randomly structured. e. Transition of a quartz–feldspar metapegmatite into a pegmatite sensu stricto. The rather homogeneous structure and preferred orientation of phyllosilicates and tectosilicates is gradually substituted for by a blocky texture along with a change in the principal type of pegmatite from a feldspar metapegmatite tabular into a Be–Nb (meta)pegmatite tabular.Püllersreuth, Germany. f. Apliticrim (ap) along theselvageof thefeldspar pegmatoid (albite–oligoclase) enriched in muscovite (ms). The phyllosilicates are only weakly arranged parallel to the contact zone between pegmatoid and hornblende gneiss. Friedmannsdorf, Germany. g. Strongly sheared feldspar pegmatoid (albite –oligoclase) (pg) exposed between wooden safety pillars at the 18 m-level of the Friedmannsdorf pegmatite mine. The pegmatoid gradually passes into the banded hornblende gneiss (hgn) of the Münchberg Gneiss Complex. The transition zone is made up of aplitic hornblende gneiss (ap). h. Feldspar–quartz pegmatoid lens-shaped (pg) within banded amphibolites (amp) of the allochthonous Zoneof Erbendorf –Vohenstrauss(ZEV).Remmelberg QuarrynearVohenstrauss, Germany. i. Close-upviewof Fig.4h displayinga pegmatoid stronglyenrichedin quartz (dark gray). j. Aploid schlieren and veinlets around amphibolite fragments giving rise to an amphibolite breccia at Mirosov, Czech Republic. Using the common migmatite nomenclature, thebreccia-likestructurehas tobe calledagmatitic(Mehnert, 1968;Ramsay and Huber,1983).Boundedbytheyellowlinesoneoftheaploidschlierenhasbeencutouttoshowthecontact at higher magni�cation. k. Thefeldspar aploid(ap) lens-shaped intercalated into amphibolite (amp). Muglhof, Germany. l. Feldspar aploid from Muglhof, Germany. m. Roof zone of a Be– Li–Ta pegmatite with an enclave of micaschistssunken into thepegmatiticmelt. Thepegmatite took accommodation withinan anticline whose limbs gently dip away from thefold crest. Thepresent-day hilly landscapeis conformable to thelithologyunderneath.Las Cuevas Pegmatite, NW Argentina.n. A stock-like “micro-pegmatite” formed in medium-grademicaschists along the borderof the Independencia Pegmatite (Nb–Be–P pegmatite). The sketch on the right-handside illustrates by the two red arrowheads the compressional strength exertedonto the metasediments and the resultant accommodation space generated in the hinge zone of the open microfold. The “micro-pegmatite” stock was emplaced late- to postkinematically. o. Criss-crossing stockwork-like pegmatite veins (REE–Nb–Ta pegmatite (fergusonite–euxenite)) held to be related to the Blomskog Granite. The gneisses are dated to 1.65 Ga. Dusserud, South Sweden. p. (Nb)–Ta–Be pegmatite (microlite-columbite) tabular in metaconglomerates. The border zone with tourmaline (enriched in dravite), spessartite and beryl (yellowishgreen) grades towards the center into feldspar. Capoeira Pegmatite, NE Brazil. q. Nb/Ta –Li–B pegmatite (kaolinized) tabular in muscovite–quartzites of Neoproterozoic age is renowned for its concentration of cuprian elbaite (Paraiba Tourmaline). Batalha Pegmatite, NE Brazil. r. Uranium plutonic pegmatite apophyses within the two-mica granite. Monte Galinero, NW Spain. s. Feldspar aplite granite (ag) in�ltratedby Mo granite aplite (ap). Molybdenite is concentrated in nests and pockets (mo). Kataberget, North Sweden. t. P–Be–Li pseudopegmatite (spodumene holmquistite) tabularexposedin anadit of theKoralpeLi deposit, southernAustria. Theore shootsare steeplydipping in thegallery towardsthe bottomright(photograph: courtesy ofR. Göd). u.The fractionation ofthe felsicmeltconduced ina subhorizontalrare-elementpegmatite, measuring2 kmin lengthand 25m inthicknessintoa quartzcoreenveloped by K feldspar. Evje, Norway (photograph: courtesy of A. Müller, Geological Survey of Norway). N

427


New EnglandPegmatite Provinceis the analogue of the pegmatite provinces in the European Variscides. The arcuate belt of these orogens resulted from the convergence, obduction and collision of two megacontinents, Laurussia in the north and Gondwana in the south. Largescale thrusting and nappe stacking caused a thickening of the crust between 380 and 320 Ma, leading to an ensialic orogen and providing a mineralogically and structurally fertile environment for the generation of all kinds of pegmatitic rocks from metapegmatites, pegmatoids, through pegmatites sensu stricto — Section 3.2. It was followed by the intrusion of a huge volume of felsic to intermediate granitoids starting off already during the Upper Devonian and lasting into the waning stages of the Variscan orogen until the early Permian

(280 Ma). The latter host rocks were the “ kitchen” of the plutonic pegmatites discussed later in the special sections — Section 3.2 (Dill, 2015). 2.2. The Proterozoic Orogenies of Gondwana

Even a brief introduction into the Precambrian orogenies and the geodynamic evolutionof Gondwanawouldgo farbeyond the topicof this review devoted to the geology of pegmatitic rocks. Therefore in this paper, the overview is narrowed down to a crustal section between eastern South America–Brazil and eastern Africa, an area abundant in pegmatitic rocks richly endowed with all elements

biotite-sillimanite gneiss

2m Meta-pegmatite

a b

c

ap

og

20 cm

20 cm

428


5 cm

5 cm

e

d

hgn ap 5 cm

f ms

pg g

ap

10cm

ms i pg

amp h Fig. 4 (continued).

characteristic for the evolution of rare metal pegmatites (Fig. 3). The mosaic of lithospheric plates making up modern-day Africa and South America is illustrated in the map redrawn from Kusky et al. (2003). It is rimmed by some fragments at its northern rim, when looked at it from the present point of view, that were incorporated into younger orogens in the same way as fragments of the Paleozoic Variscides were incorporated into the Mesozoic–Cenozoic AlpineHimalayan Fold belt (Fig. 3). The African continent relevant for the evolution of pegmatites evolved around three major Achaean cratons, from North to South, the West-African Craton, the Congo Craton and the Kalahari Craton, which are representative of the era older than 2500 Ma (Schlüter, 2006).

These three crustal nucleiare “clued” together by fold belts of Proterozoic through early Paleozoic age. The Paleoproterozoic around 2000 Ma is represented inter alia by the Ubendian Fold Belt in Central Africa, Early Neoproterozoic rocks between 1000 and 900 Ma are exposed in the Kibaran Fold Belt in East-Central Africa and by the Kamativi Fold Belt in Zimbabwe. The Late Neoproterozoic through Early Paleozoic fold belts, which evolved around 600 to 450 Ma in the Damara Fold Belt, Namibia, on the Arabo-Nubian Shield in NE Africa and in the Mozambique Fold Belt in SE Africa are put together under the term Pan-African Orogeny. The various orogens are representative of tectonic, magmatic, and metamorphic activities of Proterozoic to Early Paleozoic age in a

429


j

l k

amp

ap

Fig. 4 (continued).

crustal section which once formed part of Gondwana before the break-away from South America, involving the Br azilian Shield and several smaller cratons. The West Congo Belt forms the eastern section of the Pan-African orogenic system, part of which is now situated in the Aracuai Fold Belt in Brazil and represented there by a series of ophiolites, 800 Ma old. This geodynamic setting has also consequences for the correlation of pegmatites on both s ides of the Atlantic Ocean and forces to a joint discussion of pegmatites on both sides of the South Atlantic Ocean. On the opposite side of the African continent, the Neoproterozoic orogenies and the assigned pegmatites have to be correlated with similar ones in Antarctica, Madagascar and India (Fig. 3). Particular the Isle of Madagascar and the

SubcontinentIndia with Sri Lanka at its “tiptoe ” are abundant in pegmatite deposits, mainly in gemstone deposits related to pegmatitic rocks. 3. The classi�cation schemes of pegmatites — complexity and applicability

3.1. The history of classi �cation of pegmatites

Classi�cation of pegmatite deposits began as early as 1920 with Niggli's pioneer work followed by Fersmann (1928, 1931) and Landes's (1933) scheme and is still going on today (Dill, 2015).

430


m n

Fig. 4 (continued).

A classi�cation scheme used for mineral deposits must ful�ll certain requirements. It must cater for the extractive and the genetic part of economic geology alike and ought to be applicable in the of �ce and the �eld, where the pegmatites formed. Open access and space for amendments, preferably in its electronic or digital version, are needed so as to render the classi�cation scheme adjustable to the needs and wants of application, research and training in geosciences and is no �ash in the pan. The hierarchical levels should be open for alphanumerical coding,given that the classi�cation schemeis used in a digital version and each level must be entitled with a header that stands for all

of its items in a logical way. The present classi �cation schemes for pegmatites do not meet the conditions speci�ed in this paragraph. The classes in theclassi�cation scheme introduced by Ginsburg et al. (1979) for pegmatites “abyssal ”, “muscovite ”, “ muscovite-rare element”, “rare element”, and “miarolitic ” that later were adopted as prime level in the classi�cation scheme by Černý and Ercit (2005) do not ful�ll these requirement for special reasons. It is a mixture of substance (elements and minerals), depth estimation (abyssal) and texture (miarolitic). Description and interpretation cannot all in one form a basis for classi�cation scheme. Critical points as to the existing

431


10cm

o q

s

p r

ap

ag

t

mo Fig. 4 (continued).

classi �cation schemes of pegmatites have already been raised by Tkachev (2011) as to the applicability of such schemes. The inferior level in this hierarchy underneath the above classes is named the “pegmatite family”, made of two members,one enriched in Li, Cs and Ta, abbreviated to LCT, and the other enriched in Nb, Y and F, abbreviated to NYF. The system may � t in one way or the other but in most cases it does not. In the Hagendorf –Pleystein Pegmatite Province Li is present in three stock-like pegmatites, whereas tabular aplites and pegmatites, excluding the Silbergrube Aplite, are barren as to this element. Cesium does notplaya signi�cant role andNb always prevails over Ta,thuscontradicting any classi�cation of these pegmatites as LCT pegmatites. In

the pertinent literature above Hagendorf the pegmatite is categorized as a rare-element LCT pegmatite belonging to the beryl type. Beryl is however subordinate and trails behind other elements like P and Zn by a wide margin. Only 1 km away from the so-called LCT pegmatite at Pleystein a Sc-bearing sheet-like aplite with high values of Ti, Nb, U, Zr, Y, REE and Th was intruded into the biotite–sillimanite gneisses. According to the classi �cation scheme elaborated by Černý and Ercit (2005) this aplite would belong to the NYF family and the subclasses “REL –REE” plus “ MI-REE” (Dill et al., 2008a ). What is the consequence ofsuchaclassi�cation?LCTgranite–pegmatite systems aresaidto be related to S-type granites in orogenic settings, whereas NYF granite–

432


u

Quartz Core

Fig. 4 (continued).

pegmatite systems are derivedfromlate- to post-tectonicanorogenicAtype granites. It is hard to believe that consanguineous pegmatite systems of the late Variscan heat event around 300 Ma formed in two geodynamic settings so different from each other on a kilometer scale (Černý, 1991a). Many pegmatites do not contain the diagnostic elements as it is the case with some NYT deposits or share element combinationofbothtypescalledtheLCTandNYTfamilies,asitisthecasewith some pegmatites from Madagascar. It encouraged Pezzotta (2001) facing problems with his classi �cation of gem-bearing pegmatites in Madagascar, to come up with another classi �cation scheme integrating elements of the classical scheme of Černý (1991a) into a new one placingemphasis on reference minerals (Pezzotta, 2001). Wise (1999) tried to tackle the problem inherent in the NYF pegmatites by introducing chemical groups such as “ peraluminous” for the 1st order discrimination and a wealth of minerals for the 2nd order subdivision. Ercit (2004) again fell back on the metamorphic grade of the host rocks of pegmatites, while being conservative in the remaining items of classi�cation such as element combinations, minerals and elements. Zagorsky et al. (1999) selected a totally different criterion for their � rst-order

subdivision in their classi �cation scheme. Their systematics is based on low-, moderate and high-pressure pegmatites stuffed with the common element and mineral associations for further subdivision. Another shortcoming of most of the classi�cation schemes presented on pegmatites is on one hand their restrictive handling, using socalled reference types with diagnostic minerals and on the other hand mixing facts with interpretation (Ginsburg et al., 1979; Černý, 1991a). None of theschemes mentioned aboveis designed to introduce another set of elements or minerals into the pegmatites 'classi�cation system. In the Hagendorf –Pleystein PegmatiteProvince, Zn (inFe-bearing sphalerite and gahnite), and Bi (Bi sul �des and -phosphates) are more widespread than beryl. Arsenic (As sul�des and arsenates) and phosphorus are genetically interrelated with each other and of fundamental bearing on thepresenceand absence of As sul�des and phosphates in pegmatite systems, but left unaddressed in all classi�cation systems. All attempts to relate pegmatite types and subtypes to the origin of a speci �c magma failed and other mobilization processes, such as anatexis at depth or along shear zones cannot be addressed satisfactorily (Simmons et al., 2003).


The current classi�cation schemes may speculate on the m agmatic source at depth but do not address such issues mentioned above. If a classi�cation scheme is at odds with the natural systems and results in a puzzle of environments and settings that do not �t together we have to change the classi�cation scheme and not the natural habitat. Mostly the pegmatite deposits are pigeonholed in the various studies without trying to get to the bottom of the geological setting of formation or attempting to correlate the various types and subtypes in terms of their physical-regimes. A wayout of this dilemma is to take a more simplistic approach and to be more descriptive than speculative. You cannot explain a foreign word by means of another foreign word and if thegrammaris too complex,say it in a fewplain words. In thefollowing paragraphs such a classi�cation scheme is tailor-made for the pegmatites. In essence it is a subtype of the “Chessboard classi�cation scheme of mineral deposits” (Dill, 2010). This is particularly highlighted by the basic alpha-numerical codes used for the various commodities in

433

Section 4. A breakdown of the variegated element composition of pegmatites of the succeeding CMS classi�cation scheme is anything but trivial. The pegmatites are a complexinterplay of lithological andmineralogical processes impacted by the mantle and the crust. Consequently each element composition and mineral assemblage is split up into elements or commodity groups which are going to be analyzed as to their geological and geodynamical role they play in time and space (Section 4). Someelementsare supporting actors,while others are leading actors on this outdoor-stage. The leading actors appear again on stage in Section 7 when it comes to the economic use. 3.2. The CMS classi �cation scheme of pegmatitic and aplitic rocks C hemical composition, the M ineral assemblage and the S tructural geology of pegmatitic rocks constitute the basic ingredients of this descriptive classi�cation scheme and, hence, the acronym CMS has been

Fig. 5. a. The pegmatite deposits of Finland (Simonen, 1980; Lahti et al., 1989). b. Table of RE pegmatites and REE minerals.

434


a)

Alpine type

Variscan type

Rift type

Island arc type

Andean type

Pegmatites Calc-alkaline Reworked

Barren zone

Alk

Primary

ENSIMATIC

ENSIALIC

ENSIMATIC

b)

c) As-Bi

As-Bi-(Zn)-(Mo)

Zn+Mo

Sc

Sc

Nb/Ta

Nb/Ta+Na

(Nb/ Ta)

Li (Si)

Li (Si) Li (P) Li (B)

P

P

B

B/F< 1

kaolin

graphite (mica) (phlogopite+ vermiculite

zeolite (contact-skarn)

Th/U>1

Be

Be+Na

(Sn-W ?)

Sn-W

Sn-W+Na

Variscan type

Rift type

Alk

quartz

Alpine type feldspar

quartz Variscan feldspartype

Calc-alkaline Reworked

Primary

ENSIALIC

scapolite (skarn)

quartz Rift type feldspar

Pegmatites

Pegmatites Calc-alkaline

zeolite nepheline+ sodalite (desilication)

Zr-Ti

Be

(corundum)

alumosilicates

F

REE+Na

ENSIMATIC-ENSIALIC

Mica (muscovite)

P

REE

Reworked

(graphite)

corundum

Th/U<1

Alpine type

kaolin

garnet

B/F>> 1 Zr

kaolin

ENSIMATIC

Alk

Primary

ENSIMATIC-ENSIALIC

ENSIALIC

ENSIMATIC

Fig. 6. a. Overview of those environments favorable for the generation of pegmatites and those detrimental to the evolution of pegmatitic rocks in relation to geodynamic settings. Alk =

alkaline. b. Rare elementpegmatitesand thegeodynamicsetting (CMS classi�cationscheme — Chemical Quali�ers).Thesizeand fontof the letters are used todemarcate the signi�cance of each element in the various settings. Bold-faced means widespread occurrence, set in brackets or added up with a quotation mark means minor potential as to the accumulation of a certain elementor concentration processes uncertain. c. Common pegmatites and rare mineral pegmatites (CMSclassi�cation scheme — Mineralogical Quali�ers). Toshow theimportance of each setting for pegmatites see caption of Fig. 6b

coined (“CMS classi �cation scheme of pegmatitic and aplitic rocks”) (Table 1). The classi�cation schemehas four rows which aremandatory andthree whichare optionaldependingupon thedatabase and thepurpose of the classi�cation. The basic sections are the “Ore Body”, encompassing the levels 1 and 2 of classi�cation andthe “Ore Composition” being split up into a level 3 (chemical quali�ers) and level 4 (mineralogical quali�ers). A detailed description and the use of the

classi�cation scheme have been published in Dill (2015). Only a brief discourse is given in this review on the geology of pegmatites. 3.2.1. Crystallization versus deformation — age of pegmatitization relative to the age of host rocks

All aplitic and pegmatitic rocks occur in crystalline host rock lithologies, either of metamorphic or of magmatic origin. The 1storder term of

435


classi�cation is based upon the relation between crystallization and deformation or in an area with igneous activity only, on the timing of pegmatitization relative to the age of intrusion of the host rocks. Based upon well established and general agreed mineralogical and structural features, metapegmatites/metaaplites which evolved prekinematic/ premetamorphous can be distinguished from pegmatoids/aploids which are synkinematic/synmetamorphous or from pegmatites/ aplites which formed in the aftermaths of these regional- and dynamometamorphic processes. Moreover pegmatites can occur in intrusive rocks after the emplacement and cooling of the magma (Table 1). For basic information on these temporal relations between crystallization and deformation in metamorphic and magmatic realms, the reader is referred to textbooks on structural geology and petrology like those published by Ramsay and Huber (1983), Best (2002), Kearey et al. (2009), Fossen (2010), Turcotte and Schubert (2014). Those structural features used for classi�cation can be recognized with the unaided eye or hand lens in the � eld and determined with a background in structural geology. A sequenceof images gives a generaloverview of the structural and textural features of metapegmatites (Fig. 4a, b, c), metapegmatites transitional into pegmatites (Fig. 4d, e), pegmatoids (Fig. 4f, g, h, i, k, l) and pegmatites sensu stricto ( Fig. 4m, n, o, q) at outcrop and in hand specimens so as to ease a precise determination of these felsic mobilizates in the �eld. Plutonic pegmatites and their �ne-grained analogues, calledplutonic aplites, are shown in Fig. 4rands.

a)

Sadisdorf

Altenberg

Plutonic pegmatites are hosted by plutons of different size and petrography, most frequently of granitic and granodioritic composition. It has to be kept apart from pegmatites which have a granitic, dioritic or even gabbroic composition and may be hosted by plutons different in their composition from the mobilizates but may also be discovered in metamorphic host rocks. In metamorphic rocks the criteria mentioned above for their denomination as metapegmatites and pegmatoids have to be applied. An example of how plutonic pegmatites can form has been given by Audétat and Lowenstern (2014) who showed the gradation from normal granite into a granophyric and pegmatitic texture in thevicinity of a miarolitic cavityin granite fromthe Riodel Medio Pluton. The term pseudopegmatite has been applied to pegmatite-like mobilizates, also called remobilized pegmatites or reworked pegmatites, which, in places, may have lost their original pegmatitic or aplitic texture but based on their mineral association and chemical composition point to a pegmatitic derivation (Fig. 4t). The fractionation of the felsic melt into a quartzcore enveloped by feldspar is shown in the outcrop at Evje, Norway (Fig. 4u). In a subhorizontal rare-element pegmatite,measuring2 km in length and25 m in thicknessa white quartz core is overlain by a rim of K feldspar,appearing in mega crystals which take a size of as much as 5 m — see also, where it began in Fig. 21c. The term pseudopegmatite was introduced for the metamorphic realm to avoid during classi �cation jumping into genetic conclusions which afterwardsprove to be premature.As a type example theKoralpe

Pechtelsgrün

sediment

Sn greisen

gneiss

pegmatite

granites

quartz porphyry

granite(greisenized)

ore veins

Ehrenfriedersdorf

quartz cap Fig. 7. a.Sn–W g ranite pegmatites, greisen- and vein-type deposits of the Erzgebirge,Germany. Sadisdorf quartz-greisen-type deposit, Altenberg granite pegmatite-greisen-type deposit,

Pechtelsgrün granite pegmatite-greisen-type deposit with intragranitic veins, Ehrenfriedersdorf granite pegmatite-greisen-type deposit with veins intersecting the roof rocks (modi �ed from Rundquistet al.,1971). b. GreisenizedSn–W-bearing leucogranite at Modot,Mongolia. c. Albitization of theSn –W-bearing leucogranite at Modot,Mongolia,resultingin an aplite. d. Radiatingaggregatesof topaz (pyknite)from thegranite-hostedSn depositAltenberg, Germany.The zone of pyknite evolvedimmediately underneaththe pegmatiticstockscheider in the apical parts of thegranite copulaand shows thetypical growthof giant crystals. e. Tourmalinizedcassiterite-bearing tingranite. SouthCrofty Mine, Cornwall,GreatBritain.f. External contact of the Sn deposit at Weissenstadt, Germany (redrawn from Schneiderhöhn, 1961). g. The supercritical and subcritical stages in the Hagendorf-South Pegmatite and their structural representation. The pegmatitic–pneumatolitic transition known from Sn –W pegmatites in a phosphate pegmatite sensu stricto. h. Open pit exposing � at-lying veinlets within leucogranodiorite to adamellite hosting the Barruecarpardo W deposit, Spain. i. Aplite-granite contact marked by W veins in the Barruecarpardo W deposit, Spain. The photograph is rotated by 90° to the right. j. Arsenopyrite rosettes on fault planes veins in the Barruecarpardo W deposit, Spain. k. Veinlets of scheelite (white) and arsenopyrite (oxidized) in the BarruecarpardoW deposit,Spain. l. Openpit ofthe Ta–Li depositin albiticand greisenized leucogranite mineralized withcassiterite, columbite–tantalite and amblygonite, Golpejas, Spain.

436


b

c

3cm

5 cm

d

e

25cm

5 cm Fig. 7 (continued).

lithium deposit in Austria (Göd, 1989) andthe Greenbushes lithium deposit in western Australia are taken here (Partington et al., 1995). These types of pegmatiticand aplitic rocks taken as reference for the structural and textural variations and shown in the various images above – Fig. 4 – are treated in the succeeding sections in more detail related to the chemical compositionof pegmatite deposits, their structural emplacement and origin. To determine the aforementioned structural features in the � eld is mandatory for the classi�cation, but unfortunately not available in all cases studied. Describing the host-rock lithology of the pegmatites and making it part of the classi �cation is optional and depends of the aim of the investigation, e.g., pegmatoid (cordierite –sillimanite –gneiss) (Table 1). The classi�cation has been designed so as render possible also a retroactive view and classi �cation handling this classi�cation scheme on a limited database with only chemical composition, mineral assemblage

and moderate overview of the structure but it encourages provide full particulars in the future. The CMS classi�cation scheme can be used in its long version, applying all terms listed in Table 1. Given only a limited database, the classi�cation can be also run in its short version, using only term 3 and 4, as exempli �ed in the index of sites (Table x). Irrespective of the database, the classi�cation scheme is designed so as to be used also in a digital data base on PC. (See Table xx.) 3.2.2. Shape and structure of pegmatites

In addition to some standard terms that may illustrate the shape of the pegmatitic rocks in a simple way, such as tabular, schlieren, stocklike, or vein-type, the applicant of the CMSclassicizationscheme can de�ne further descriptive quali�ers and use them as a 2nd order term for classi�cation. Some of these morphologies, however, will be restricted to the plutonic pegmatites, such as pod-like or miarolitic, the latter ad jective has also been used by Černý (1991a) and by Černý and Ercit

437


f) Quartz veins Pegmatitic margin Greisen + Sn, F, As, Cu Granite Mica schist

m

g)

0

5

10

20

Host Anticline pipe Older Pegmatite

Quartz Core Gneiss

Stage 2 Fig. 7 (continued).

(2005). For those who can read the book of structural geology in the �eld the shape can tell them, e.g., where the material came from, what the pathway was, and whether the material has come out of the surrounding rocks or from a different place far off. Furthermore they might get some ideas about the timing of the various pegmatites in a certain pegmatite province. The pegmatitic rocks can be assigned a certain style and phase of deformation so thatthe variouspegmatite bodies

are no longer erratic rocks but architectural elements �tting into a dynamo-metamorphic plan. Consequently these felsic intrusive rocks are amenable for incorporation into an exploration plan for pegmatitic deposits. It has to be noted that a lot of study needs to be done to provide the information necessary for the proposed pegmatite classi �cation because the current literature on pegmatites is almost devoid of such investigations (Cameron et al., 1949). The majority of pegmatitic

438


floors

h

i

k floors

j

l Fig. 7 (continued).

and aplitic bodies are sheet-like or tabular in shape and of variable thickness and striking length (Fig. 4a, q). Some pegmatites s.str. occur as stockwork-like bodies or form veins (Figs. 1a, 4 j, o). There is a great variety of irregularly-shaped bodies, predominantly arcuate pegmatite bodies which trace the volume of an anticline and, to a lesser extent, syncline (Fig. 4m, n). The hinge and trough areas of fold structures stand out as to be the most preferred loci for the emplacement of pegmatites. In a compressional regime accommodation space runs through a maximumin thehinge areasof folds in metamorphic rocks,giving rise to stock-like bodies,whereas the limbs of anticlinal structures onlyprovide enough space for tabular bodies, following the rules of mimic tectonics or do not show up at all as a “ trap” for these felsic melts. Deepseated lineamentary fault zones cutting through isotropic host rocks, such as intrusive igneous rock as well as schistose metamorphic rocks used to form tabular pegmatitic bodies or en echelon dike swarms. See later in the review for shape and morphology also the photographs and line drawings of Figs. 7a, f, g, 8a, b, c, 9a, b, c, d, 11, 19d, 23c, 24a, b, c, g, 36c, d, 45a, b, c, and 46 in the pertinent sections. The size of pegmatites is optional, but may be of utmost importance when it comes to a decision for mining engineers or entrepreneurs to open up the intrusive body or leave it. Internal zonation is a term often to be heard of in context with pegmatites. The most recent thoughts centered on this term were made public by Thomas and Davidson (2015). Fractionation would tend to increase the volatile concentrations, and zonation would result from the r esidual melt passing from the stability � eld of one mineral to the next in order of evolving composition and decreasing temperature. This general assessment can also be applied to hydrothermal/subcritical vein-type deposits which

feature a characteristic bilateral zonation or a unidirectional growth zonation as well as sheet-like or tabular pegmatites starting off from supercritical �uids/melts. The onion-shell like arrangement of zones around a granite have often been published in cartoons like in Černý et al.(1989), but closerlookat themany geologicalsections willprovide with a different view as we willsee also in this book. In miarolitic granitic pegmatitesit maystill work in some places but upgrading the levelto the size of pegmatite ore body does no longer allow us the term zonation. Many have their mineralizations patchily distributed in the individual ore bodies closely controlled by the tectonic processes and we can longer speak of a mono-phase emplacement but have to invoke a series of different processes. See later in the review of pegmatites and pseudopegmatites in Figs. 7g, 24a,b, c,g, and 46a. for internal zonation. Many of them have a thinselvage at the contact with the wallrocks but their internal arrangement of mineral assemblages is anything but a symmetrical arrangement which allows for the use of the term zonation. The aplite at the selvage can best be compared with the chilled margin of many sills, but therest of the story of pegmatiteemplacement includes a variegated spectrum from multiphase intrusions through replacement, to mention only few of the processes in this general discussion. The term zonation has rather blurred our picture of the formation than contributed much to a better understanding of the formation of pegmatites and deviate our view from the true nature of pegmatites as they are emplaced in nature. This becomes obvious even in the classical study conducted by Cameron et al. (1949). The closer we look at the longitudinal or cross sections drafted by the mining surveyor we get the impression of a patchy arrangement of mineral associations with the implication of a rather complex emplacement. If we shift our

439


Tin pegmatites

Super floors

a Basement undifferentiated tourmaline gneiss

tourmaline pegmatite

500m

b migmatites

schist

schist 1000m

c Basement undifferentiated

500m

Fig. 8. a. Cross sectionthrough theSn-bearing Manono–Kitolopegmatite, DR Congo.In thecrosssection thetopography andthickness is showntwice as muchas in reality(redrawnfrom

Bassot and Morio, 1989). b. Cross section through the Sn-bearing Kamativi pegmatite, Zimbabwe, plus host rock geology (redrawn from Pelletier, 1964). c. Individual ore shoots of the Kamativi pegmatite (redrawn from Fick, 1960; Rijks and van der Veen, 1972). Each ore shoot forms an anticline with both of its limbs gently dipping away from the hinge zone.

eyes towards cartoons the “onion-shell zonation” is conspicuous. As an economic geologist working underground in different types of mines I have always based my con �dence in a large-scale underground map performed by a mining engineer or surveyor. 3.2.3. Chemical and mineralogical composition of pegmatites

Chemicalquali�ers (3rd order term of classi�cation) and mineralogical quali�ers (4th order term of classi�cation) are secondto none from whatever angle youmight look at thepegmatite, whether from a genetic or economic point of view. It is, however, often not that easy to get a full blown picture of the chemical or mineralogical composition of a pegmatite in the �eld or even after trenching due to the heterogeneous lithology and the zonation which can be unraveled only when opening up the pegmatite with drillingoperations. Therefore chemical and mineralogical parameters were not given a higher order within the hierarchical CMS classi�cation scheme and ranked lower than the relative ageof pegmatitization and the 3D-representation of the aplitesand pegmatitesin nature. Thelatter arekey in linking thepegmatite ore body to the geological setting, otherwise it will end up as a “�ying carpet”. It has to be noted that the lion share of raw material extracted from pegmatites is feldspar, quartz and mica, and only a tiny fraction of less than 10% of pegmatites contains rare elements at a level so as to render mining of these rare-element pegmatites feasible. The 3rd order term and 4th order term of classi�cation are a mirror image of the tripartite subdivision into ore minerals (chemical quali�ers — rare element pegmatites), industrial minerals (mineralogical quali �ers — non-rare element pegmatites, also denominated as barren pegmatites) and gemstones plus decoration stones (mineralogical quali�ers — non-rare element pegmatites bearing colored gemstones) used in the “ Chessboard Classi�cation Scheme of Mineral deposits” (Dill, 2010)

(Table 1). These quali�ers will be used in the succeeding paragraphs for classi�cation. The 1st and 2nd order terms cannot strictly be used in the current review since only a small part of pegmatitic and aplitic rocks in modern-day publications addresses the age of formation and the 3D-representation of these rocks in nature. You know the ore composition butit is dif �cultto relateit intime and space tothe overall geological setting. I am hopeful that the pioneer studies of Cameron et al. (1949) who summarized a lot of spatial data on pegmatites in the USA and the book of Schneiderhöhn (1961) who published the most comprehensive study on pegmatites worldwide at that time were not all in vain andmayencourage geoscientists to see pegmatites as an integral part of the geodynamic–geological evolution and not only as a treasure box full of colorful minerals (Dill, 2015). Feldspar, quartz and mica form the main constituents of granitic rocks as well as of pegmatitic rocks. Therefore these ubiquitous rocks need not be explicitly named in a classi �cation scheme dealing with granitic and pegmatitic rocks and emphasis is placed upon the rareelement contents.If however, the student of a special type of pegmatite feels it is essential to place emphasis also on these common constituents, it is no violation of the rules of the CMS scheme to name a pegmatite,e.g., in a way like that: Al albite-oligoclasepegmatite(ruby).It is the group of minor constituents next in abundance to the aforementioned rock-forming silicates and the commodities, which the pegmatite is operated for, that play a decisive role in a more detailed classi �cation scheme. All elements concentrated during the emplacement of these pegmatitic rocks such as Sn, W, Ta, Nb, Sc, Be, Li, Cs, Rb, REE, U, Th, B, F, and P can be used tospecify the pegmatitic rocks. Five to six quali�ers may be suf �cient in practice to render the classi�cation scheme manageable, even though there is no real limitation to the number of quali�ers, as long as the relative abundance of elements is considered. The

440


elements are arranged in the order of decreasing abundance with the most widespread marker-element next to the 1st order term, e.g., Sn– Sc–Nb pegmatite that is a pegmatite most strongly enriched in Nb

a

while Sc prevails over Sn. This approach is not new but has already successfully been applied by the Geological Survey of Finland for the pegmatite deposits situated in the Precambrian metamorphic and igneous

floors

b

Quartz porphyry Sn greisen

d

Granite

c

Fig. 9. a. Stackedpegmatiteveins (seeyellowarrowheads) from the main lode drive of South CroftyMine, Great Britain(photograph: LeBoutillier, 2002). Seemeterfor scale. b. Cross sec-

tion of thestrongly greisenizedtwo-mica granite at Panasqueira, Portugal (modi�ed from Kelly andRye, 1979). The cupolais overlainby a silica capand surroundedby schistose country rocks. The topmost partis intersected by a stacked set of subhorizontal ore veins (�oors). R = rise. c. The concave Sngreisen zone is parallel to the contact between the apical part of the host granite and the country rocks (modi �ed from Rundquist et al., 1971). It is controlled by the onion-shell-like joint system of the granite at Zinnwald (Germany)/Cínovec Sn deposit (Czech Republic). d. Onion-shell exfoliation in the course of weathering following the rules of the granite tectonic. The present-day topography (yellow full line) accentuates the cupola of theFlossenbürg Granite (P-bearing granite). Thestacked convexjoints (yellowstippled line) aremore or lessparallel to theweathering surfaceof thegranite. e. Resistivity-depthfunctionmeasured by MMT (=medium-magnetotelluric) in areaswith exposures of different pegmatitic rocks(modi�edfrom Haak,1989),Germany.f.Re�ectionseismic surveyalonga cross section perpendicular to the geodynamic zone of the Central European Variscides at the western edge of the Bohemian Massif (see also Fig. 2a for location). I: Seismic re �ectors dipping towards the S. II: Geodynamic interpretation and positioning of the structural types of pegmatitic rocks according to the CMS classi �cation scheme. HPPP denotes the area of the Hagendorf-Pleystein-Pegmatite Province. The area is geodynamically characterized by thrusting and nappe stacking. ZEV = Zone of Erbendorf-Vohenstrauss + Teplá-Barrandian zone or Bohemicum.

441


Beidl B-Be pegmatite

e) 10 -2

10 -1

] 10 0 m k [ h t 10 1 p e D 10 2

10 3 10 -1

10 0

10 1

10 2

10 3

10 4

RHO [OHM M]

f)

Seismic reflectors Frankenwald

MGC

Fichtelgebirge

Oberpfälzer W. ZEV

I

Böhmer Wald

Plutonic pegmatites Pegmatoids> metapegmatites

Metapegmatites> pegmatoids

HPPP

II

Pegmatites+aplites Pegmatite(skarn)

Geodynamic interpretation

Fig. 9 (continued).

rocks (Simonen, 1980; Lahti et al., 1989 ). There is no way to do it any better than to describe the deposits in this simple and most realistic style by the Finish geologists (Fig. 5a, b). For genetic or economic reasons it might make sense to supplement the term as shown in Fig. 4t. In case of lithium pegmatites, the main element may be accommodated in the lattice of spodumene or phyllosilicates such as zinnwaldite or lepidolite, and thus it is advisable

to use one of the Li minerals as quali �er, e.g., Li –Nb–P pegmatite (amblygonite) versus Li –Nb–P pegmatite (triphylite). At the Koralpe Li deposit, southern Austria, it is a P –Be–Li pseudopegmatite (spodumene N holmquistite) tabular. For comparison and to demonstrate the applicability, some more rare-element-bearing feldspar pegmatites in the close vicinity of the Koralpe Li deposit are classi �ed according to the current classi�cation scheme (Ucik, 2005): Spittal

442


Table 2

Rare elements and minerals in pegmatites sensu lato as a function of their geodynamic setting. Element

Type of pegmatite

Intracrustal setting and mobilization

Subcrustal setting and mobilization

Sn

Granitic pegmatites transitional into greisen- and vein-type deposits, pegmatite-(skarn) Granitic pegmatites transitional into greisen- and vein-type deposits, pegmatite-(skarn) (Granitic pegmatites to) pegmatites, rarely in pegmatoids and metapegmatites. Also in pseudopegmatites Pegmatites, minor pegmatite-(skarn)

Frontal part of nappes, collisional environment

Deep-seated lineaments and embryonic and failed rifts

Pegmatites, minor pegmatite-(skarn) Pegmatites, minor pegmatite-(skarn) Granitic pegmatites transitional into greisen-type deposits Pegmatites related to anorogenic granitoids Granitic pegmatites transitional into greisen-type deposits, pegmatites, pegmatite-(skarn)

Preferably orogenic–ensilialic, anatectic

W Be

REE U Th F B

Frontal part of nappes, collisional environment Towards the root zones of nappes or core zone of ensialic orogens

Frontal part of nappes, collisional

P

Metapegmatites transitional into pegmatites and aplites, pseudopegmatites, pegmatite-(skarn)

Li–Cs–(Rb)

Granite pegmatite (with Sn, F), pegmatites and pseudopegmatites

Nb–Ta–(Sc)

Pegmatites, minor concentration in pseudo- and metapegmatites

As–Bi–Zn

Pegmatites, minor concentration in pseudopegmatites

Enrichment due to local preconcentration in crustal sections

Mo

Granite pegmatites, pegmatite-(skarn)

Feldspar

Granite-, syenite, rhyolite pegmatite, pegmatoid, metapegmatite, pegmatite s.str. Pseudopegmatites, pegmatite-(skarn)

Quartz

Granite pegmatite, pegmatoid, metapegmatite, pegmatite s.str.

Feldspathoids scapolite Feldspathoids nepheline + sodalite Feldspathoids zeolite

Pegmatoid, pegmatoid-(skarn)

Frontal part of nappes, collisional environment Magmatic and metamorphic origin. Relative to quartz pegmatites, feldspar pegmatites are emplaced at a shallower level Magmatic and metamorphic origin. Relative to feldspar pegmatites, quartz pegmatites are emplaced at a deeper level Magmatic to metamorphic in origin

Alumosilicates + F- and B-bearing

Pegmatoid, pegmatites, pegmatite-(skarn), pseudopegmatites (?)

Corundum

Syenite pegmatites, pegmatite-(skarn)

Garnet

Pegmatites, metapegmatites, pegmatite-(skarn) Granite pegmatite, pegmatoid,

Muscovite

Deep-seated lineaments, rifts, mantle af �liation

Secondary enrichment and high reactivation potential

Deep-seated lineaments, rifts, mantle af �liation

Ensialic, orogenic parametamorphic rocks, nappe emplacement, geodynamic marker in the core zone-proximal. Deep erosional level Ensialic, orogenic parametamorphic rocks, nappe emplacement, geodynamic marker in the core zone-distal, anatectic Ensialic orogens intracrustal recycling by anatectic processes in parts mediated by subcrustal processes. Concentration of Li and emplacement of its pegmatites closely linked to shear zones and thrusting. Strong geodynamical zonation from the frontal parts of collision zones to the root zones of nappes, where subcrustal heat may add up to the mobilization of Li Tracer for metamorphic and magmatic fractionation processes

syenite pegmatite Granite-, syenite pegmatites, pegmatites, pegmatite-(skarn)

Reactivation

Secondary (hydrothermal) processes in the aftermaths of calc-alkaline magmatism and contact metasomatism Metamorphic–anatectic origin, controlled by the metamorphic regime and the parent material of the crustal rocks Metamorphic–magmatic, as far as the main component is concerned of crustal af �liation, chromophores may be of subcrustal origin Metamorphic–magmatic Magmatic and metamorphic origin.

Preferably anorogenic, ensimatic Anorogenic, ensimatic

Secondary enrichment and reactivation possible Secondary enrichment and lower reactivation potential than P Secondary enrichment and stronger reactivation potential than B Secondary enrichment and very stronger reactivation potential. Dismembered pseudopegmatites

Anorogenic, ensimatic impact common particularly to Nb and Sc Enrichment due to local preconcentration in subcrustal sections and near the root zone of nappe complexes — see Zn Mo skarn related to A-type magmatic rocks

Moderate to extreme enrichment, particularly with respect to Ta Moderate enrichment, particularly with respect As and Bi

No indication for reactivation

Quartz pegmatites may be representative of subcrustal origin when associated with Ti-, Nb-, Zn-minerals. See also C A-type magmatism in some Mo deposits Alkaline magmatism, plus desilication

No indication for reactivation

Not known

Alkaline magmatism Present in reactivated pegmatitic rocks, but no indication as to whether it is part of the neomorphism Sapphire in syenite pegmatites

443

H.G. Dill / Ore Geology Reviews 69 (2015) 417 –561 Table 2 (continued)

Element

Type of pegmatite

Phlogopite Graphite

metapegmatite, pegmatite s.str Pegmatoid, pegmatite-(skarn) Syenite–pegmatite, pegmatoid, pegmatite-(skarn)

Kaolin

Intracrustal setting and mobilization

Metamorphic–magmatic origin

Granite pegmatites, pegmatites, pegmatoids, metapegmatites

Subcrustal setting and mobilization

Reactivation

Subcrustal source Subcrustal source for syenite pegmatites and some quartz pegmatites

Supergene alteration dependent upon the size of the outcrop Hypogene alteration extremely ef �cacious when the roof rocks are still intact

a.d. Drau: P –Be–B, plutonic pegmatite near Villach: P –B–Be, Erling near Spittal: P –Be–Be, Wildbachgraben/Steiermark: Nb/Ta –Be–Li, St. Radegund near Graz: B–Li–Be. The data have been derived from different sources. These terms are more in accordance with nature and tell us much more than the word LCT granite pegmatite, when cesium cannot be pinpointed mineralogically at site, and the columbite s.s.s. is enriched in Nb rather than Ta and no granite is close by. A list of elements beingpartof theterm to classifya pegmatite may spark criticism, but even minor elements can play a part in that their major host minerals capture elements in the pegmatite system and thereby may become of control on the element composition of others. The data of Bilal et al. (1998) may be interpreted this way. When boron forms part of the chemical composition of pegmatites and shown in the list of elements used for classi�cation one can better understand the Fe/ Mn ratio in columbite s.s.s. Tourmaline may alter the Fe/Mn ratio to such an extent that the columbite precipitation no longer can go on unbiased. The industrial minerals other than feldspar, quartz and mica in a pegmatitic rock can be described by a mineralogical quali �er in a way like that: quartz–feldsparmetapegmatite withcorundum, or graphitepegmatite. In the � rst case it is a metapegmatite that could be mined for the common ceramic raw materials quartz and feldspar provided that the amount of corundum is not detrimental to the run-off mine ore. In the second example it is a graphite pegmatite as described in Section 4.16. Colored gemstones and ornamental stones are not the second but the third string to the bow in terms of raw materials extracted from

pegmatites (Pezzotta, 2001; Simmons, 2007; Shigley et al., 2010 ). Other than the common industrial minerals quartz and feldspar or tantalum and niobium for which pegmatites are still an important source, colored gemstones won by local diggers and small-scale miners are dif�cult to quantify as to the mine output, be it of jeweler's or showcase quality — see also Section 7. The classi�cation system put forward in the previous paragraphs can be handled in the same way. A sapphire pegmatite tabular is a pegmatite s.st. with sapphire as the main commodity, while a F-Sn-W plutonic pegmatite (topaz) miarolitic contains topaz in miaroles and has also the potential for a rare-element pegmatite, particularly for Sn and W. For reasons of �nal use, it may sometimes be advisable to provide full particulars as to the composition of feldspar, e.g., albite pegmatoid, rose quartz pegmatite, scapolite –sapphire pegmatoid. It is not only the mining engineer or gemologists who may reap the bene�t of this more detailed mineral description but it enables geoscientists also to �ne-tune the physical–chemical regime of pegmatitization. Ab initio, a pegmatiteis de�ned by its chemical/mineralogicalcomposition and by its three-dimensional shape. This is valid irrespective of the depth of emplacement,or theage of formation. Whether you seethepegmatitic rocks as a source of raw materials or as an objective for genetic study, this descriptive classi �cation scheme is a sound basis for both camps of economic geology to live with. It is not dogmatic, open for amendments and whatever mineral or element a user adds to the classi�cation scheme, it will be self-explanatory and acceptable to any reader.

Table 3

The classi�cation of Sn-W-bearing and their geodynamic setting. Mineral province

CMS classi�cation of pegmatites

Interpretation

Chronology

Structural type 1st order

Shape 2nd order

Chemical quali�er 3rd order

Mineralogical quali�er 4th order

Geodynamic setting

Igneous rocks

Central Europe (Variscides-PermoCarboniferous) Western Europe (Variscides-PermoCarboniferous)

Granitic pegmatites

Stock-like

Li mica + Li –Al phosphate

Ensialic, collisional, nappe thrusting

S-type granites, anatectic

Granitic pegmatites and aplites

Stock-like, pipes, tabular (�oors)

Mo–Zn–Bi–U–F– (As)–B–Be–Li–P– Sn–W P–Li–F–As–Sn–W to REE–U–F–Nb/Ta– Be–B–Li–P–Sn–W

Li mica to Li mica + Li–(Al) phosphate + spodumene

Ensialic, collisional, nappe thrusting

Eastern Africa (Kibaran — Neoproterozoic)

Pegmatites

tabular

(Cs–Pb)–Nb/Ta–Li– Sn to (B –REE–W–P)– Nb/Ta–Sn–Li

spodumene + Li mica to pollucite + Li–(Al) phosphate

Ensialic, collisional, nappe thrusting, initial rifting

Central South America–Brazil (Rondônia — Neoproterozoic to Early Paleozoic) Western Africa–Nigeria (Older Granite SuiteLate Neoproterozoic Early Paleozoic)

Pegmatites to granite pegmatites

Layered to + vein-type

P–Li–F–Nb/Ta–Sn–W

Li mica

Ensialic–ensimatic, rifting

S-type granites, anatectic moderately stronger mantle impact (see ophiolitic Lizard complex) S-type granites, anatectic with stronger mantle impact Sn albitites, A type granites underneath the pegmatite � oors A-type granites strong mantle impact

Pegmatites

vein-type

Nb/Ta–Sn

Ensimatic, failed rift

A-type granites strong mantle impact

4 4 4

H . G . D i l l / O r e G e o l o g y R e v i e w s 6 9 ( 2 0 1 5 ) 4 1 7 – 5 6 1

Fig. 10. a.The distribution ofprecious Be-bearinggemstonedepositsrelated to pegmatites by country andby geology. Itis extractedfromthe map“Gems andGemstones by Country andGeology — Beryllium” (modi�ed from Dill andWeber, 2013).b.

Pegmatitic, mega crystal of white opaque beryl ore from La Toma, Argentina. Length of scale bar 16 cm. c. Pegmatitic pinkish massive beryl (morganite) from the Quintos pegmatite, Brazil. For scale see the thickness of the biro. d. Non-pegmatitic beryllium ore with �uorite containing 1% BeO from the nodular beds of the Pliocene tuffs of the Spor Mountain deposit in Utah, USA ( Dill, 2010).


The third strong point of the CMS classi �cation, lies in its use as a key element or legendformappingprojects. A similar approach hasalready been taken and tested for the metallogenetic map 1:2,500,000 available on CD (Dill et al., 2008b,c). In the succeeding Section 4, the basic ingredients of this classi�cation scheme discussed in Section 3.2.3 are used as header for the individual sections and thegapbetween description andinterpretation of thegenesis of pegmatites is closed. Themain focus is theintegration of the pegmatites intothe economicgeology,while the interpretation of thephysical-regime,which without anydoubt is important, is kept to a minimum and performed in some of the papers quoted in the reference for the deposits under consideration and exempli�ed for the pegmatite province along the western edge of the Bohemian Massif with full particulars given in Dill (2015). 4. Commodities and the origin of pegmatites

To prevent a classi�cation scheme and its terms fromending up as a stopgap in a research paper, the various elements and element associations (chemical quali�ers) as well as minerals and mineral assemblages (mineralogical quali�ers) need to be correlated with the geology, to be more precise with the geodynamic setting (Fig. 6a). Five reference settings have been selected and checked whether they are favorable or detrimental for the emplacement of pegmatitic rocks. The key setting for the pegmatites is the ensialic Variscan-type setting which is characterized by crustal thickening. Large part of the Variscan-Alleghanian orogeny in Europe and North America is representative of this type. The Alpine-type fold belts extending from Western Europe into East Asia are considered as a model for reworked pegmatites. This crustal section has ensimatic and ensialic components. The Rift-type shows a thinning of the crust which during its incipient stages is the preferred locus foralkaline magmatismand also forthe emplacement of pegmatites. The Oslo Graben can be taken as a reference for thistype. Andean- andIsland-Arc-typesettings are barren to pegmatites as exempli�edbythe “RingofFire”. Only theinnermost partsof the Andean-type, proximal to the shield containspegmatites, e.g., in Bolivia. Rare element pegmatites – Sections 4.1 to 4.9 – are discussed in relation to thethree settingsrife with pegmatites (Fig. 6b). The subdivision of pegmatites is carried out using thechemical quali�ers in the CMS classi�cation scheme. Common pegmatites, sometimes also called barren pegmatites owing to its lack of rare metals and rare minerals are dealt with in Sections 4.10 through 4.17. They are represented by the mineralogical quali�ers of the CMS classi�cationscheme (Fig. 6c). More details as to the various elements and minerals with respect to the crustal and subcrustal setting of source and reactivation are listed in Table 2. The codes used in

445

the “Chessboard classi�cation scheme of mineral deposits” are given in rounded brackets in the subtitles so as to facilitate linking the precise environment of formation of pegmatites s.l. with the environment of associated mineral deposits (Dill, 2010). It highlights that pegmatites are not a stand-alone deposit but form part of the economic geology of mineral deposits. 4.1. Tin- and tungsten pegmatites and pegmatite –skarns (12 DE)

Tin and tungsten are key elements among the granite-related deposits. The morphology of ore bodies spans the complete range from pipes, chimneys, curved and �at-lying ore bodies in the apical parts of felsic igneous rocks, through faultbound Sn–W deposits in the roof rocks to stock-like and large tabular pegmatitic ore bodies which do not show any link to granites of whatever chemical composition they might be (Fig. 7a). In hydrothermal solutions, chloride and hydroxychloride complexes are the most ef �cient transporters of tin as SnCl2, SnOHCl and Sn(OH)2Cl2 (Wood and Samson, 1998). The most recent Sn–W deposits of the Late Paleozoic Sn –W belt of the European Variscides have been subjected to an intensive study during the last decades. In this European metallotect (a technical term used in this review to demonstrate the unity between a mineral province and a crustal section undergoing metamorphic–kinematic disturbances) all sorts of Sn –W mineralization from intragranitic, through greisen-type, pegmatitic, to vein-type can be observed-special literature cited in the succeeding section.The interaction of pegmatitic rocks with their cogenetic structural types of Sn–W mineralization such as greisen or stockscheider can best be studied in the Late Variscan Orogen using the CMS classi �cation scheme put above for categorization (Section 4.1.1). The results obtained are interpreted genetically so that they can also be applied to older mineralized sites, e.g., for pegmatitic deposits in Proterozoic rocks (Sections 4.1.2 to 4.1.4). 4.1.1. Sn–W plutonic pegmatites in the Variscan Metallotect

Tin and tungsten are both bound to the Saxo-Thuringian geodynamic zone, or outer external zone of the Central European Variscides (Fig. 2a, Table 3). Lithology and structure of this geo-dynamic zone are characteristic of a rift basin Cambro-Ordovician in age. A great variety of sedimentary and volcanic rocks formed in this basin from the Precambrian through the Lower Carboniferous, when the Visean tectonic disturbances once and for all put an end to the basin development. Near the Cornubian Sn–WOre�eld – see below – the Lizard Complex was emplaced. It has all hallmarks of an ophiolite sequence, known from many modern fold belts, such as in Oman or the Isle of Cyprus ( Jones, 1997; Cook et al., 2002).

446


. )

d e u n i t n o c (

0 1 . g i F

447


in the Moldanubian Zone is no Sn–W deposit but enriched in Li and Nb. Neverthelessit is from thestructuralpoint of view not very much different from the Sn–W deposits (Fig. 7h). Cassiterite and wolframite in the Erzgebirge area are almost exclusively related to the younger granites (older granites: 330 –310 Ma, younger granites: 305–290 Ma) (Baumann et al., 1986; Seltmann and Faragher, 1994; Tischendorf et al., 1995; Breiter et al., 1999; Webster et al., 2004; Romer et al., 2007 ). However, there are obviously exceptions from the rule. For example, radiometric age dating by Kempe and Belyatsky (1997), using the Nd144/Nd143 and Sm147/Nd144 methods, yielded a Namurian formation age (321 –326 Ma) for the Sadisdorf Sn–W mineralization. Sn –W mineralization occurs in the endo- and exo-contact area of the Sn–F–Li granites and may locally

Fig. 10 (continued).

Tin and, to a lesser extent, tungsten are closely related to granitic rocks and as far as the pegmatitic rocks are concerned, they can be taken as a reference type of plutonic pegmatites according to the classi�cation scheme put forward in Section 3. Metalliferous pegmatites coded 12a D and 13b D by Dill (2010) carry a variegated spectrum of minerals besides cassiterite, wolframite and scheelite as demonstrated by the most well-known Ehrenfriedersdorf — (Mo–Zn–Bi–U–F–As)–B– Be–Li–P–Sn–W plutonic pegmatite deposit (Tischendorf et al., 1995; Spallek, 1996). Thomas et al. (2009b), who investigated the miarolitic granitic pegmatites in this region published a crystal growth temperature of smoky quartz of ≈ 650 °C. The Erzgebirge Sn –W mining region is a classical example to show the close intertonguing of Sn –W granite pegmatites with greisen- and vein-type deposits (Fig. 7a). The Ehrenfriedersdorf deposit is compared with the Sadisdorf, Altenberg and Pechtelsgrün Sn–W deposits from the Erzgebirge, Germany, illustrated in the series of cartoons of Fig. 7a. Moreover, this comparison is also extended to some reference deposits further to the West, in the Fichtelgebirge, Germany (Fig. 7f) and to some from the southern MoldanubianZone (Fig. 7g). The Hagendorf-South pegmatite, Germany,


448

H.G. Dill / Ore Geology Reviews 69 (2015) 417 –561 Table 4 (continued)

Table 4

Beryllium-bearing pegmatites by country and geology – see also Fig. 10a as a 2-D representation – worked for beryllium-bearing minerals of gemological quality (modi�ed from Dill and Weber, 2013). Plus legends for the maps Fig. 10a country and geology. No.

Site

Country

Mineral

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73

Adun-Tschilon Mountain Alto Ligonha Analalava District Andapa District Andilamena Andravory District Ankazobe–Vohambohitra Antandrokomby Antsongombato Apaligun AraþuaÝ Baragoi District Barra De Salinas Rubelita Benson Betafo-Antisabe Bikita Boise Borborema Bulache (Gilgit) Burmado Carnaiba Region Carrara Near Harar Castelinho Chamachhu Chitral Coimbatore Danba Danie Darra-I-Pech Doce Doko-Balistan-Gilgt Dusso (Balistan-Gilgit) Embu-Meru Erongo Mountain Espirito Santo Gascoyne Godarpur Governador Valadares Gur-Salak Konar Province Gwantu Haddam Harris Hematita Irondro Itabira Itaguau Iveland Jaguaribe Area Kapiri Mposhi Karoi-Miami Khaltaro-Gilgit Knoydar Kobokobo Kotokay Kuangding Kukurt Kunar Lake Alaotra District Las Palomas-San Luis Leeuw Kop Leeuwspruit Little Three Mine, Ramona Lundazi Area Luumõki Makanjior Malakialina Mawi Miass Mursinska District Mursinska District Mwani Baboon Hill Nagar Hunza Valley Nassarawa

Russia Mozambique Madagascar Madagascar Madagascar Madagascar Madagascar Madagascar Madagascar Pakistan Brazil Kenya Brazil Zimbabwe Madagascar Zimbabwe USA Brazil Pakistan Brazil, Bahia Brazil Ethiopia Brazil Pakistan Afghanistan India China South Africa Afghanistan Brazil Pakistan Pakistan Kenya Namibia Brazil Australia—Western Australia Pakistan Brazil Afghanistan Nigeria USA Great Britain Brazil Madagascar Brazil Brazil Norway Brazil Zambia Zimbabwe Pakistan Great Britain Congo China China Tajikistan Afghanistan Madagascar Argentina South Africa South Africa USA Zambia Finland Tanzania Madagascar Afghanistan Russia Russia Russia Zimbabwe Pakistan Nigeria

Aquamarine Beryl Beryl Beryl Beryl Beryl Beryl Rhodizite Rhodizite Aquamarine Aquamarine Beryl Aquamarine Beryl Beryl Beryl Aquamarine Aquamarine Beryl Beryl Chrysoberyl Beryl Chrysoberyl Aquamarine Beryl Beryl Beryl Beryl Aquamarine Aquamarine Aquamarine Beryl Beryl Aquamarine Aquamarine Beryl Beryl Aquamarine Aquamarine Emerald Beryl Beryl Chrysoberyl Emerald Chrysoberyl Chrysoberyl Aquamarine Aquamarine Beryl Beryl Emerald Beryl Beryl Aquamarine Beryl Aquamarine aquamarine Chrysoberyl aquamarine Chrysoberyl Beryl Beryl Beryl Beryl Beryl Beryl Aquamarine Beryl Aquamarine Beryl Aquamarine Aquamarine Emerald

No.

Site

Country

Mineral

74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111

Nilaw Orissa Pattalai Pikes Peak Pingwu Rio Grande Do Norte Sambesi Graben Santa Leopoldina Santa Tereza Sherlovaya Gora Shigar Valley Shingus-Dusso Sibweza Sichuan Sierra De Ancasti Sierra De Cordoba Sierra De San Luis Sierra Velazco Socoto Spitzkopje Stak-Nala Teo�lo Otoni Teo�lo Otoni Terra Branca Minas Gerais Thach Khoan Thomas Range Tisgtung Topsham Triunfo Tsaratanana 2 Valadares Wah-Wah Mountains Willie Wolodarsk Wonder Well — Menzies Xuan Le Area Yuanyang Zambue

Pakistan India India USA China Brazil Zambia Brazil Brazil Russia Pakistan Kashmir-Pak Tanzania China Argentine Argentine Argentine Argentine Brazil Namibia Pakistan Brazil Brazil Brazil Vietnam USA Pakistan USA Brazil Madagascar Brazil USA South Africa Ukraine Australia—Western Australia Vietnam China Mozambique

Beryl Aquamarine Aquamarine Aquamarine Beryl Aquamarine Beryl Chrysoberyl Chrysoberyl Beryl Aquamarine Beryl Beryl Beryl Beryl Beryl Beryl beryl Chrysoberyl Beryl Aquamarine Aquamarine Beryl Aquamarine Beryl Beryl Aquamarine Aquamarine Chrysoberyl Beryl Aquamarine Beryl Beryl Aquamarine Emerald Aquamarine Beryl Aquamarine

extend into the pegmatitic bodies also related to these Late Variscan granites (Thomas and Webster, 2001). The Altenberg, Germany and Zinnwald/Cínovec deposits, Germany–Czech Republic are among the best known Sn deposits of Europe and thus described in more detail below (Dill et al., 2008b,c ). The mineralizingstage characterized by greisen-,vein-type and pegmatitic Sn–W deposits, taking place subsequentlyto solidi�cation of the granitic melt was given a name of its own and called pegmatitic – pneumatolitic phase by Schneiderhöhn (1961) (Fig. 7a). The term has not really become well established in the geoscienti �c community and describes the transitional stage from the supercritical to the subcritical �uid system. The same author described from a trial mining operation targeted upon Sn near Weissenstadt in the Fichtelgebirge, a gradual transition from the normal granite, into a coarse-grained granite pegmatite with graphic intergrowth of quartz and feldspar. Towards the country rocks a quartz-enriched greisen zone with cassiterite and arsenopyrite comes into existence next to the pegmatite. The contact between the greisen and the mica schists around is very sharp (Fig. 7f). The Sn ore mineralization is exclusive to the greisen, whereas the pegmatite is left barren as to Sn minerals. The Altenberg Sn deposit is located in the contact zone of the Altenberg granite porphyry and the Teplice quartz porphyry. The main ore minerals are cassiterite, wolframite, and molybdenite (Baumann et al., 1986). The Altenberg granite forms a stock-shaped intrusion in the granite porphyry with extensive greisen zones measuring 300 to 400mindiameterand230minverticalextension( Fig.7a).Greisen refers to a pervasively altered lithium–albite granite in which feldspar and biotite are converted into a disseminated assemblage of quartz, topaz, muscovite, zinnwaldite and protolithionite (both Li-micas), cassiterite, sericite, � uorite, dickite, kaolinite, wolframite and scheelite (Fig. 7b).


Strong albitization in granite-related Sn–W deposits may give rise to “aplitic rocks” (Fig. 7c). Pegmatitic parts in the apical parts of the Sn granites altered to topaz (pyknite), zinnwaldite,andquartzwere calledby the ancient miners as “Stockscheider” (Fig. 7d) (Thomas and Davidson, 2013). Fig. 7a gives an overview of the various subtypes and illustrates the evolution from greisen-type Sn–W deposits through pegmatite-hosted (“Stockscheider”) to vein-type deposits. All subtypes of the silica capgreisen-pegmatite-vein system illustrated in Fig. 7a for the Erzgebirge Sn–W deposits have one thing in common, a pronounced vertical extension resulting in a chimney-like or pipe-like shape of the Sn–Wbearing ore shoots. This is especially well demonstrated in the Sadisdorf- and Altenberg-type deposits. The ore shoots developed on top of the apical part of the Late Variscan granites. A mixed vertical – horizontal zonation turned into a vertical-only zonation with the onset of the pegmatitization in the Altenberg-type. Excluding the Ehrenfriedersdorf-type, all greisen-types are endogreisens affecting the granitic host rocks, proper. Variscan granitoids of widespread occurrence in the Erzgebirge/ Krušne Hory Mts. (Germany–Czech Republic) formed between 340 and 310 Ma andhave been attributedto theS-type andhigh-K I-typegranites (Finger et al., 1997). The youngest group of leucogranites in Central Europe formed between 300 and 250 Ma, during the late Carboniferous and Permian, when highly-fractionated S-type granites and A-type granites were concentrated across the Fichtelgebirge and the Erzgebirge. The (Mo–Zn–Bi–U–F–As)–B–Be–Li–P–Sn–W granite pegmatite at Ehrenfriedersdorf is chemically a good match to the granite types. De �nition: The term skarn coined by Swedish geologists is used here in its traditional and rather descriptive way in context with pegmatites, because of its close spatial relationship with pegmatitic rocks, leading in some places to rare-element mineral associations of economic interest, particularly for gemstones. It is a rock-type enriched in amphibole, pyroxene, garnet and further Ca silicates, such as vesuvianite whichhave replaced calcareous sedimentary rocks or basic to ultrabasic igneous rocks leading to an exoskarn within the wall rocks and, locally, to an endoskarn in the producing intrusive rock, of granitic or pegmatitic type. As exempli �ed in the book, there is often no sharp boundary between these contact-metasomatic and contact-metamorphic rocks.

Granite-related mixed-type Sn–W deposits of this kind do not only occur along the Czech–German border in the Erzgebirge/Krušné Hory Mountains but also pass towards the West into the Cornwall Sn–W district, Great Britain, which is a match to the Central European Sn–W deposits and which has pegmatites also besides, greisen-, vein-type deposits and tourmalinized tin granites (Fig. 7e). This type of cassiterite-bearing Sn granite is rare among the host granites, but extraordinary for its radially oriented acicular tourmaline crystals. In the Cornubian mining region a polymetallic mineralization, involving Cu-, As-, Zn-, Pb-, Ag- and Co minerals, is associated with the Sn mineralization. Pegmatites developed during the initial mineralizing phases together with skarns and were followed subsequently by post-granitic lodes and veins bearing the aforementioned polymetallic mineral associations (Guilbert and Park, 1986). All kinds of structural types of granitic pegmatites/aplites, such as pods, schlieren, veins, lenses and “stockscheider” were reported from the Cornubian granites (Dines, 1956; Dunham et al., 1978; Badham, 1980 ). They are syn- to postgranitic and re�ect a strong heterogeneity within the host granitic system as to � uid migration and viscosity during the latest phases of granite emplacement. Radiometric age dating yielded an age of formation for the Halvosso Pegmatite of greater than 285 Ma attesting to its emplacement in the aftermaths of the Carnmenellis Granite (Halliday, 1980; Clark et al., 1993 ). The rare metal pegmatites bear tourmaline, zinnwaldite, apatite, chlorite, stokesite, topaz, triplite arsenopyrite, loellingite, wolframite and cassiterite (Dines, 1956). According to the mineralogical assessment made by LeBoutillier (2002) the rare element pegmatites may be classi�ed as P–Li–F–As–Sn–W granite pegmatites, while the majority of pegmatites can only be worked for feldspar and mica.The author describes the presence of pegmatites in the Cornubian

449

Ore�eld as fairly rare, due to the extensive fracturing in the late-stage solidi�cation stage, which saw the � uids migrating into the fractures forming lodes rather than accumulating within the granite itself. Alderton (1993) reported a temperature of formation in the range 250 °C to 460 °C for the pegmatite. Dines (1956) and LeBoutillier (2002) described quartz �oors in cylindrical zones extending vertically for over two hundred meters in dip height. They interpreted these features as tensional fractures that were in�lled by granite-derived �uids in response to internal shearing in the still-plastic granite. These structures carry a mineralogical association of true pegmatites. Ore-shoots of a pronounced vertical extension for several meters are also known from the Erzgebirge deposits and less conspicuously expressed even in some phosphate pegmatites of the Hagendorf –Pleystein Pegmatite Province (Fig. 7g). A two stage-evolution can be deduced from the cross section of Fig. 7g. In a host anticline made up of biotite –sillimanite gneiss and sill-like granites the felsic melt has been intruded during stage 1, the funnel-shapedverticalstructure evolved during stage 2. Tin mineralization is present in this pegmatite but only at subordinate amounts together with a varied spectrum of sul�de minerals (Mücke, 2000). What in previous textbook was described as the pegmatitic-pneumatolitic stage, e.g., by Schneiderhöhn (1961), is denominated now as the supercritical (pegmatitic) and subcritical (pneumatolitic) state in thesedeposits. This comparison between Sn–W granite pegmatites and P pegmatites sensustricto isa manifesto that various stages can be telescoped into each other in complex pegmatites, such as those from the Hagendorf –Pleystein Pegmatite Province – seea more detaileddiscussion inSection 4.6.1 – andthat complex mineral assemblages can be disentangled into more simple ones basedon thechronologicaland geological data available so that theorigin of these rock can better be determined. One of the giant deposits sensu Laznicka (2014) enriched in W is the Shizhuyuan greisen- andskarn deposit in China, which is hostedby Devonian

Fig. 11. Pegmatite-related schist-hosted emerald deposits in Zambia (from Dill, 2010).

450


limestone in the thermalaureole of the Qianlishan granite complex. Tungsten is concentrated in scheelite and wolframite which occur together with Bi in massive W –Bi–Mo–Sn skarn ore, stockwork W –Sn–Bi–Mo–F ore, and W – Sn–Mo–Bi greisen ore a granitic complex with �ve separate intrusions (Jingwu Yin et al., 2002). There exist also some Pb – Zn– Ag ore bodies related to this granite complex. True pegmatites have not been recorded from this large deposit. Shizhuyuan is the largest polymetallic tungsten deposit in China. Ore reserves amount to 750,000 t of WO 3, 490,000 t of Sn, 300,000 t of Bi, 130,000 t of Mo, 200,000 t of Be ore (combined grades 1% to 5%). There are additional �uorite reserves of 7000 t, making it also one of the largest associated �uorite deposits in China (source: internet database).

Another giant deposit of this type is located in Vietnam. The Nui Phao deposit, Vietnam, is hosted in skarns and their greisenized or retrograde equivalents. Greisenization consists of high � uorine, beryllium, tungsten, tin and limited rare earth metals, which have replaced granitic dykes and earlier-formed skarn units (Northern Miner, 2001). The Da Lien two-mica granite is estimated to be late Cretaceous in age, and is considered to be the main source of mineralization in the area. The medium-to-coarse grained granite consists of light-colored alkali feldspars and micas and is enriched in tin, tungsten, beryllium, bismuth, niobium and lithium (Northern Miner, 2001; Ishihara and Orihashi, 2014). It is said to be the largest tungsten deposit in the world and one of the largest �uorite deposits

a) 1000 COLG 100

WPG Bogd uul

) m p p ( b R

Modot

ORG VAG COLG WPG

VAG

10

Tsagaan davaa

= ocean ridge granit e = volcanic arc granite = collisional granite = within plate granite

ORG

1 1

10

100

1000

(Y+Nb) (ppm)

b)

1.6

Metaluminous

l 1.4 o m ) O 2 1.2 K + O 2 a N ( / 1.0 3 O 2 l A

Peraluminous

Bogd uul Modot Tsagaan davaa Peralkaline

0.8

0.8

1.0

1.2

Al2O3 /(Na2O+K2O+CaO) mol

c)

8 7 6 5

Bogd uul

(Shoshonite series)

) 4 % t 3 w ( 2 O 2 K 1

Modot

High K

Tsagaan davaa

Medium K

Low K

0 45

50

55

60 65 70 SiO2 (wt %)

75

80

Fig. 12. a.Y+Nbvs.RbdiagramelaboratedbyPearceet al.(1984)is toshow thegeodynamicsettingof thegraniticrocks. b. Chemical discrimination ofplutonicrocksbasedupon themol

ratios using Al2O3, K2O,Na2O and CaO (Maniar and Piccoli, 1989). c. Chemical discrimination of plutonicrocks based upon the weight percentage of K2O and SiO2 (LeMaitre et al., 1989).


too, with a projected production of 190,000 t of �uorite per annum. True pegmatites have not been recorded from this large deposit, either.

While the Sn–W mineralization in the French part of the Variscan Orogen is rather modest, these commodity group known from the Erzgebirge and Cornwall is widespread in the Variscan massifs along the western boundary of the Iberian Peninsula. There are true Sn –W– Ta deposits such as Barruecopardo and Golpejas in Spain, the Panasqueira Sn–W deposit in northern Portugal which has a silica cap on top of a granite cupola and subhorizontal aplites, and pegmatites present over a wide area of more than 100 km alongthe Serra de Estrela granitic massif, and many pegmatites on the Iberian Peninsula strongly enrichedin cassiterite(Derréetal.,1986) (Fig.7h,i,j,k,l, Table3).Inthe pegmatites of the Amarante Region, Northern Portugal, the Cañada Pegmatite in Castile and Leon, Spain, in the Lalín pegmatite �eld, in Galicia, Spain, Ponte Segade area in Galicia, NW Spain, and granitic pegmatite dikes of the La Canalita, Navasfrias Sn–W district, Spain, Sn mineralization has been observed among other elements (Maijer, 1965; Fuertes-Fuente et al., 2000; Roda et al., 2004; Llorens and Moro, 2010; Canosa et al., 2011, 2012 ). In the USA, the structural differentiation into quartz veins and pegmatites resembles closely what has been described from the Variscan metallotect in Europe. Minor occurrences are in the Appalachian Sn belt, and in the Black Hills, South Dakota. Cassiterite is frequently accompanied by a spade of minerals containing Nb/Ta, Be, Li and P. 4.1.2. Sn–W pegmatites in the Neoproterozoic Metallotect in Africa

A true pegmatite-hosted Sn deposit is located at Manono-Kitolo, DR Congo, which is the most well-known representative of a Sn – W–Nb –Ta –Be –Li province along the eastern boundary of the DR Congo with Burundi, Rwanda and Uganda ( Pelletier, 1964; Bassot and Morio, 1989; Ngulube, 1994 ). The deposit consists of two separate tabular zoned pegmatites with a striking length of as much as 6 km. The deposit was attributed to the metallogenic event around 900 Ma (Fig. 8a). Manono-Kitotolo is a postkinematic pegmatites of the Lower Kibaran (Proterozoic) for which the succeeding types of pegmatites have been mapped in the region: (1) microcline–quartz –muscovite, (2) microcline–quartz–plagioclase (albite –andesine), (3) plagioclase (albite) –quartz–spodumene–mica, (4) microcline–plagioclase –spodumene (Table 3). The mineral assemblage encompasses cassiterite, columbite–tantalite, thoreaulite, loellingite, rutile, ilmenite, arsenopyrite, pyrite, galena, Fe- and Mn oxides. Spodumene is present in amounts of up to 20% and makes these deposits to one of the biggest Li resources in the world. Spodumene formed more or less contemporaneously with beryl whereas cassiterite came slightly later than the Li minerals. Columbite s.s.s. has been accumulated in the greisen-type mineralization where it is associated with thoreaulite. Thoreau (1950) and Varlamoff (1972) provided an overview of the mineral assemblage of the pegmatite. Cumulative production since 1919 is reported to stand at 180,000 t of cassiterite concentrate (Bassot and Morio, 1989). Theauthors assume that this subhorizontal sheet-like pegmatite originated from an injection parallel to the roof of parentalgranite underneath. It displays, however, unidirectional growth zones from bottom to top and it is hard to believe that a parallel injection of melt took place over a striking length of12kmandgaverisetoabodywithawidthof50to800m(Bassot and Morio, 1989). The country rocks are metasediments (phyllite, quartzite, chert) and greenstone, with steeply dipping schistosity planes which are cut by the �at-lying pegmatite. Among the granites in the close vicinity a red leucogranite was held accountable for the pegmatite. The granite is of S-type, it is peraluminous, depleted in REE, but with a pronounced negative Eu anomaly, and plots as syn-collisional in the Rb – Hf –Ta or Rb –Yb–Ta plate tectonic discrimination diagrams (Günther and Ngulube, 1992; Pohl et al., 2013 ). This stands in opposition to the assumption of granite underneath the ore body published by Bassot

451

and Morio (1989). According to Pohl et al. (2013) the highest Sn and Ta concentration, is associated with yellowish albitite. A similar tin pegmatite is said to form part of the early Neoproterozoic metallogenesis around 1000 Ma in Eastern-Central Africa and was found further south, in Zimbabwe at Kamativi and Kalinda in the Magondi Belt (Fick, 1960; Gallagher, 1967; Rijks and Van der Veen, 1972; Petters, 1991) (Fig. 8 b, c). In Kamativi these unzoned tin-bearing pegmatites were probably formed by intrusive silicate melts with three mineral phases to be superimposed on each other: 1. alkalifeldspar–quartz–spodumene; 2. quartz–albite; 3. muscovite–quartz (Rijks and Van der Veen, 1972). The Kamativi pegmatite is only vaguely zoned with primary spodumene and secondary petalite. Based upon the compositional data published by the above authors both pegmatites have to be categorized as follows: ManonoKitolo ((Cs –Pb) –Nb/Ta–Li–Sn pegmatite tabular (spodumene + Li mica)), Kamativi ((B–REE–W–P)–Nb/Ta–Sn–Li pegmatite tabular (spodumene + petalite N amblygonite)). Both pegmatites are of Neoproterozoic age according to Gäbler et al. (2011) whose age estimates plot in the range 925 to 1026 Ma. The early Neoproterozoic Kibaran Belt running along the eastern boundary of the Congo Craton, where the Manono-Kitolo pegmatite formed, is contemporaneous with the Kamativi Belt in Zimbabwe, running along the SE boundary of this craton. Cahen et al. (1984) and Dewaele et al. (2013) pointed to the intrusion of voluminous Mesoproterozoic S-type granitoid massifs and subordinate ma�c bodies. Both pegmatites from Africa are �at-lying tabular pegmatites with some antiforms that cut across the steeply dipping Precambrian gneisses, schists and migmatitic country rocks (Pelletier, 1964; Rijks and van der Veen, 1972). The tabular pegmatites neither form a subhorizontal coherent layer or a seam cutting across the subvertical Precambrian units for several kilometers, nor do they show up in dome-like structures indicative of a granite underneath. It is a stacked pattern of anticlines with their limbs gently dipping away from the hinge zone and which can be traced over several kilometers (Fig.8c). Another argument against a batholithunderneath is the arrangement of the country rocks that dip almost vertically (Fig. 8b). Similar in composition,the Järkvissle pegmatite, Sweden, may be referred to as an example for Sn pegmatites from Scandinavia. It is a (Nb–

Carbonatites Areas with numerous carbonatites Fig. 13. Carbonatite occurrences in Africa (Bosse et al., 1996).

452


Be)–Sn–Li pegmatite (Smeds, 1990; Romer and Smeds, 1997). These Paleoproterozoic pegmatites resulted from a melt derived from orogenically-thickened continental crust. Pegmatitic derivates indicative of subcrustal processes and a thinning of the crust are coeval or younger than the aforementioned types. Postcollisional extension may be reported also from younger orogenies in Europe and elsewhere on the globe. Apart from the Kibaran pegmatite-hosted Sn mineralization there is another belt stretching along the SW coast of Africa in the Damara Belt (von Knorring, 1970). The oldest Sn pegmatite was reported from the Barberton Belt, Kaapvaal Craton, with an age of 3100 Ma, which is at the same time and the oldest pegmatite ever found in Africa (Maphalala et al., 1989; Maphalala and Trumbull, 1998; Trumbull, 1995). The intrusives did not evolve from a remelting of a 3500 to 3600 Ma old Ancient Gneiss Complex. Maphalala et al. (1989) favored an underplating model with a signi�cant component of juvenile magma. The high Sr initial ratios suggest that the granites in the Tin Belt and the

pegmatites are remelting products of older sialic crust. Tin is the oldest granophile or pegmatophile commodity that was concentrated by a process different from fractionation of a parental granite. In south-western Africa Sn pegmatites are con�ned to the Central Zone of the Damara Orogen where they occur in three NNE-trending belts (Uis, Karlowa and Strathmore), emplaced in form of en-echelon structures (Diehl, 1993a,b). Uis pegmatites are simple unzoned tin pegmatites while the remaining ones are more complex Nb/Ta–Sn–Li pegmatites. 4.1.3. Sn–W plutonic pegmatites of the Neoproterozoic Rondônia Province, Brazil

Thewell-known tinprovince of Rondônia (1600 to 990 Ma)in Brazil is associated in time and space with Rapakivi granites (Teixeira et al., 2007). The Younger Granites of the Rondônia province yielded U –Pb ages between 998 and 974 Ma ( Bettencourt et al., 1999). Lithologically they consist mainly of amphibole –biotite alkali –feldspar granite,

1 cm

a 1 cm

b

c 1 cm

No. 2+4 = max. U-Th-REE No. 1+3 = min. U-Th-REE

2 mm

d

Fig. 14. a. Opaquegrayish to yellowish brown zircon and K feldspar on arfvedsonite from the Mount Malosa agpaitic alkaline pegmatite, Malawi. b. Dark gray opaque bipyramidal zircon

from the K feldspar zone. Calcalkaline La Independencia, Totoral Pegmatite Field, San Luis, NW Argentina. c. Brownopaque zircon innepheline syenite pegmatites in the southern part of Seiland Island, Norway. d. For comparison, four multi-colored zircon groups from an alkaline basalt of the Eger Rift-Reichsforst, Germany (Photograph: Siebel et al., 2009).

453


1mm

1mm

b

a 1mm

c

d

Fig. 15. a. Uraniferous columbite-(Fe) with uraninite epitactically intergrown with the host mineral. Uraninite shown in this image is a complex intergrowth of the hexahedron (100),

octahedron (111) and the dodecahedron (110). Uranium “black ore” from the Hagendorf-South pegmatite, Germany (photographer: B. Weber). b. Uraniferous columbite with Fe phosphateovergrownwith uranium “yellowore” minerals. It is an integrate of torbernite (green) into autunite (yellow). Kreuzberg Pegmatite, Pleystein, Germany. Germany (photographer: B. Weber). c. Th-bearing brown monazite irregularly intergrown with columbite-(Fe) at Hagendorf-South pegmatite. It is the most common host of LREE in pegmatites (photographer: B. Weber). d. U–Th-bearing xenotime crystal under the SEM. Malosa pegmatite, Malawi. It is the most common host of HREE in pegmatites.

syenogranite, topaz–lithium mica albite granites with which Sn-, W-, Nb, Ta-, Cu-, Pb- and Zn mineralization is associated. The �uorine-rich peraluminous alkali–feldspar granites contain topaz and/or muscovite or zinnwaldite and have geochemical characteristics comparable to the low-P sub-type topaz-bearing granites. Stockworks, veins, bed-like greisen and tabular pegmatites form the ore shoots (Bettencourt et al., 2005). Tabular marginal pegmatites are bound to the Correas Massif

(603 ± 7 Ma to 619 ± 11 Ma) ( Goraieb, 2001). The initial intrusions are metaaluminous monzogranites to syenogranites, the latter syenogranites and alkali feldspar granites. The Bom Futuro deposit (Li–F–W–Sn pegmatites tabular and veintype) is different from other tin deposits of the Rondônia Tin Province, and presents a good opportunity to better understand the relationship between pegmatite and greisen deposits (Leite et al., 2008). Anorogenic

Fig. 16. Section through the intragranitic uranium deposits at Rössing, Namibia.

After Berning (1986).

454


a

b

d c e

Fig. 17. a. Tourmaline–quartz pegmatite (schorl–dravite) in theSvratka Unit (MoldanubianZone) near Pernstein, Czech Republic. b. Batalha Pegmatitewithelbaite tourmaline, thecentral

zone of which is �lled with lepidolite, Brazil. c. “Ore” from the Batalha Pegmatite. Hand-picked Paraiba Tourmaline pieces of jeweler's quality. See biro re �ll for scale. d. Aggregates of dravite in the pegmatite near Luc Yen, Vietnam. e. Pink elbaite and green verdelite accompanied by lepidolite. Las Cuevas Pegmatite, NW Argentina.

topaz granite porphyry and topaz rhyolite porphyry were intruded into gneisses andamphibolites with ages probably older than 1330 Ma. Two phases of Sn mineralization gavean age of 994 ± 3 Maand 993 ± 3 Ma, respectively. The older and major pegmatite bodies occur as lenses and veins and are internally zoned. The mineral assemblage consists of quartz, topaz, K-feldspar, zinnwaldite, cassiterite, stannite and base metal sul�des. Tin-mineralized greisen occurs mainly as pipelike structurewith quartz,zinnwaldite, topaz, �uorite,cassiterite, wolframite, pyrite, and base metal sul�des as accessory minerals — for structures see also Section 4.1.

Late Proterozoic anorogenic granites are accountable for this Sn province, where pegmatites are still present besides greisens and veins. Its deposits bound to alkali granite complexes are scattered along a NE–SW trending zones extending over 250 km. It is oneof these deep-seated lineamentary fault or rift zones that sparked mantle plumes to evolve at depth and giant ore deposits at shallower depth within the crust (O'Driscoll, 1985; O'Driscoll, and Campbell, 1997; Kutina, 1993, 1999, 2001; Kravchenko, 1999; Laznicka, 2005, 2014 ). These deep structures with their hotspot activity can be traced into the Nigerian tin province beyond the Atlantic Ocean.

FLUORINE (Chessboard classification scheme of mineral deposits No 32 sensu DILL 2010)

a) 180°

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31 2 17 25

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27 Namibia Botswana

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10.000km

Fig. 18. a. Thedistributionof �uorinegemstone deposits relatedto pegmatitesby country andby geology. Itis extractedfromthe map “Gems andGemstones by Country andGeology — Fluorine” (modi�ed from Dill andWeber, 2013).For legend see

Fig.10a. b. Thedistributionof borongemstone deposits relatedto pegmatites by country andby geology. It is extracted from the map “ Gems and Gemstones by Country and Geology — Boron” (modi�ed from Dill and Weber, 2013) For legend see Fig. 10a.

4 5 5

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. )

d e u n i t n o c (

8 1 . g i F

BORON (Chessboard classification scheme of mineral deposits No 30 sensu DILL 2010)

b) 180°

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57 4852 6

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Uzbekistan GE AM AZ Turkmenistan

Syria LB Iraq IL JO

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Pakistan

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34454749 24 46 19 38

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Fig. 18 (continued). 4 5 7

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d Fig.. 19. a. Mass Fig Massivetourm ivetourmalin alinee in theBatal theBatalha ha Pegm Pegmatit atite, e, Braz Brazil,knownfor il,knownfor itsblue Par Paraib aibaa Tou Tourma rmalin lines.b. es.b. Thetourm Thetourmali aline ne pegm pegmatit atitee at Taq Taquar uaral,Brazil al,Brazil,, hos hostt fra fragmen gments ts ofbiotit ofbiotitee–cordierite

gneiss, now �oat oatingas ingas slic slices es wit withinthe hinthe fel felsic sic roc rock. k. It is qua quarrie rriedd to use thi thiss pegm pegmati atite te as orn orname amenta ntall sto stone.See ne.See pers person on forscale.The inse insett dow downri nrightgives ghtgives a clo closese-up up viewof a sch schorldisorldissemination in the pegmatite. c. Geological cross section of the Coronel Murta Pegmatite Field (modi �ed from Pedrosa-Soares from Pedrosa-Soares et al., 1990, 2001). 2001). Late Proterozoic Salinas Fm.: quartz– micaschists, micasch ists, metagr metagraywack aywackes, es, calcsil calcsilicate icate rocks, Middle Neopro Neoproterozo terozoic ic Macaúb Macaúbas as Fm.: quart quartzites. zites. d. Corr Correlationof elationof intern internal al struct structure ure of pegmatit pegmatites es to their morph morphology ology and 3-D posit position. ion. I) Lens-shaped, subhorizontal pegmatites. II) Balloon-shaped pegmatites dipping at high angle along fractures (modi�ed from Pedrosa-Soares from Pedrosa-Soares et al., 1997; Pedrosa-Soares et al., 2001). 2001).

4.1.4. Sn–W pegmatites of the Neoproterozoic Older Granites, Nigeria

In Nigeria across the Atlantic Ocean post-orogenic Older Granites were intruded into the basement where they gave rise to Sn –Nb–Ta-

bearing pegmatites (Küster, (Küster, 1990). 1990). Okunlola Okunlola (1998, 2005) delineated seven pegmatite �elds in south-western, central and northern Nigeria with thousands of pegmatite veins attaining a length of as much as

460


1500 m, and a thickness of as much as to 50 m, which were intruded into metasediments and minor amphibolites and dolerites as well as gneisses, granites and metavolcanics (Okunlola, 2005). The Nb/Ta–Sn pegmatites belong to the Older Granite Complex. The staple product was cassiterite during the mining period with 247 t in the Ijero area, and 117 t in the Egbe area, Nigeria (Schaetzl, 1971). Matheis (1987) and Tkachev (2011) reported Rb–Sr data for muscovite. Their cooling ages fall in the range 535–555 Ma which is a minimum age of emplacement of the vein-type and tabular pegmatites. Similar Sn pegmatites were studied by Haapala (1997) in the type locality of the Rapakiv Granite in Scandinavia. In the 1.57 Ga Eurajoki stock in southwestern Finland, the ore system is composed of biotite– hornblende–fayalite granite,biotite granites and a late-stagecrystallization of topaz-bearing granite, as well as related topaz-bearing rhyolite (ongonite) dykes. Cassiterite accumulated in greisen and in pegmatites bearing a Sn–Be–W–Zn mineralization.

4.1.5. Synopsis of Sn–W pegmatites

Tinand tungsten need to be a more special handlingbecauseof their physical–chemical regime within which the deposits formed. Their primary mineralization evolves from the supercritical to the subcritical stage, a transitional section which once was called the pegmatitic – pneumatolitic state. Not surprisingly both elements show up in a wide range of sub-environments (Table 3) and the morphology of their ore shoots is the most variegated one among the elements and minerals under study. 4.1.5.1. Ore shoots and the physical regime at depth. Greisen ore bodies and

granitic pegmatites may easily be accounted for and related in time and spaceto the adjacentgranites. Tabular pegmatites which takean intermediate position in term of their morphology and the geodynamic setting need a more detailed treatment as to their geological setting (Table 3). The subhorizontal Precambrian Sn pegmatites in Africa may be termed

b

a d

e h

h= hagendorfite w= wolfeite w

w

Fig. 20. a. Dark phosphate pocket (green arrowhead) in the core zone of the Santa Ana Nb –Be–P Pegmatite, NW Argentina. b. Stockwork-like veinlets in K feldspar (white) mineralized with

primary Fe–Mn phosphates triplite, and zwieselite (dark) in the central zone of the Pacher Pegmatite near Junco, Brazil, in quartz –biotite schists. Head for scale on the right-hand side. c. Faultbound mineralization of secondary Fe phosphates (green arrowhead) including mainly blue phosphosiderite, red variscite and cyrilovite in the Boa Vista Pegmatite, Brazil. d. Dark blue well-shaped stubbyhexagonal prismsof apatitejeweler's qualityCapoeira-1Pegmatite, Brazil.e. Massivehagendor�te intergrown withwolfeite fromHagendorf-South Cornelia Mine,Germany.

461

H.G. Dill / Ore Geology Reviews 69 (2015) 417 –561 “super �oors” — see

also Section 4.1.1. The namesake behind this term is found in the dike swarms in the Late Paleozoic Cornubian Ore �eld where the pegmatite bodies vary in thickness from a few centimeter to a meter with an inclination between 0 and 20° (LeBoutillier, 2002) (Fig. 9a). The Panasqueira Sn–W deposit in Portugal, is characterized by a set of subhorizontal ore veins overlying and cutting through the strongly greisenized cupola of the twomica granite which was intruded about 290 Ma ( Kelly and Rye, 1979). It may be concluded simply from the cartoon in Fig. 9b, that the veins are younger than the granite and its silica cap. The veins are horizontally very extensive but mineralized only in a narrow interval extending vertically for 100 to 300 m. While the aforementioned Sn deposits have individual ore structures with gently dipping limbs away from the hinge zones, the greisen zones in the Sn–W–Li deposit of Zinnwald/Cínovec (Germany/Czech Republic) consists of a system of regular steeply dipping convex veins in the greisenized zones of a granite body, with quartz, wolframite, scheelite, cassiterite, zinnwaldite, topaz, � uorite, muscovite, Li-mica and feldspar (Fig. 9c). The occurrence of sheet joints is related to the cooling of the granite. It controls not only the emplacement of the greisen but become exposed near-surface during exhumation and unroo�ng of granites (Fig. 9d). A continuous catena of evolution may be depicted changing from sickle-shaped onion-shell-like joint patterns of ore control for the intragranitic Sn–W greisen, through granite pegmatite � oors within pipes and chimney, into laterally extensive subhorizontal super-�oors which may be spatially related to granites as at Panasqueira or occur as true pegmatites with no granite close by. While the intra-granitic greisen zones are related in time and space to the cooling of the magma and solidi�cation history of the granite, the pegmatite �oorsdeveloped after theemplacement of thegranite. In thepipes or chimney of the Erzgebirge and Cornubian Ore�eld, the presence of minerals containing B and F attest to an overpressure of high volatiles which was channeled through tensional fractures. Taylor (1965) considered these �oors resulting from trust zones and tensile stacked shears. Farmer and Halls (1993) saw them as the missing link between magmatic/granitic and hydrothermalmineralization, usedthe oldterm as “pegmatitic pneumatolitic ” sensu Schneiderhöhn (1961). The speci�c structures may be held to be caused by the upward movement of volatile components to theupward apical part of thegranite,involvingthe transport of incompatible elements like Sn, Li, B or W. This works only during the formation of the greisen zone as shown in Fig. 7a and c. In case of Panasqueira and all the more so in the African pegmatite deposits (Figs. 8a, b,c, 4.1.5b) this model can no longer be applied, as the granite disappears from the scene as a source of �uids and only acts as a local conduit for � uids from a much deeper source. Who is in this case the “deus ex machina” at depth?

resistivity “hump” close to the basement boundary fault. According to the geophysical working group, at a depth of about 10 km a layer of high conductivity with 0.1 Ω m has been identi�ed by both LOTEM and MMT measurements. Another shallow conductor exists between 300 and 1000 m, according to AAMT well below 10 Ω m and according to AMT of 50 to 100 Ω m (Haak, 1989). The low resistivity layer at shallow depth can be interpreted as an accumulation of graphitic matter or highly saline waters. Organic matter appears

a b

c

4.1.5.2. Deep geophysics. If we do not want to speculate on petrological

processes without evidence we have to take refuge to geoelectric resistivity measurements to answer this question. Haak (1989) and his study-group carried out such measurements during a pre-well-site study for a super-deep drill hole (Fig. 9e). As this regional deepsounding covered also part of the area rife with pegmatite deposits along the western edge of the Bohemian Massif, these data were reinterpreted in view of thegenesis of pegmatitesby Dill(2015). Different electromagnetic methods with different sensitivities to different aspects of the electrical conductivity were applied and summarized: (1) magnetotellurics (MT), (2) medium-magnetotelluric (MMT), (3) audio-magnetotelluric (AMT), (4) controlled source audio magnetotelluric (CSAMT), (5) time domain electromagnetic method (LOTEM), (6) Schlumberger direct current method (DCR). The 1-D measurement shows the resistivity to be lower underneath some pegmatites. The 2-D results obtained by means of the various methods revealed a low-resistivity zone known from the foreland to dip down under the basement with a pronounced low-

1m Fig. 21. a.

Anatectic pegmatoid with cordierite, schorl, biotite and alkaline feldspar (“migmatite”), V ěžná 5 Pegmatite, Czech Republic. b. Anatectic pegmatoid made up of K-feldspar and quartz bordered by a paleosome of biotite, Strontium Granite in North Scotland, Great Britain. c. In-situ pegmatite formation by partial melting of amphibolites (assumed anatexis age 910–915 Ma) in a road cut near Iveland Village, Norway (photograph courtesy of A. Müller, Geological Survey of Norway).

462


Table 5

Two reference types to show diagnostic features of granitic and pegmatitic uranium deposits (modi �ed and supplemented from Rogers et al., 1978). Characteristic

Rössing

Bokan Mountains

Lithology Source Th/U ratios Initial Sr isotope ratios Level of erosion Level of emplacement Tectonic vs. mineralization Age Geodynamic setting Metamorphic grade

Pegmatite–alaskite–gneiss, anatectic Reworked and recycled sialic crust Less than 1.0 Greater than 0.710 Deep Catazonal Syn- to late tectonic Proterozoic to early Paleozoic Orogenic/ensialic Medium to high-grade amphibolite facies and granulite facies

Alkaline and peralkaline granites, syenites, commonly albite-riebeckite granites Mantle or lower crust Greater than 1.0 Less than 0.710 Shallow Epizonal Post-tectonic Post-Achaean Anorogenic to post-orogenic/(ensimatic) All facies type including unmetamorphosed country rocks

during the primary mineralization in the pegmatitic rocks. These zones have restricted vertical extension but are horizontally rather extensive, a feature pretty well in accordance with the tabular pegmatites in Africa, which similar to the horizontal low-resistivity zones cut across the lithology (Fig. 8b). The zones are interpreted in terms of fracking zones caused by natural � uid overpressure generated by a magmatic body (?). The Sn–W granite pegmatites are located in the Fichtelgebirge Anticline in the autochthonous partof the SaxothuringianZonewhich forms a klippen in thestackedpattern of thenappes (Fig. 9f — “granitepegmatite”). The zone of high conductivity underneath the pegmatites (Fig. 9e) may be interpreted to coincide with one of the prominent subhorizontal layers or thrust zones, in terms of structural geology (Fig. 9f). 4.1.5.3. The geodynamic setting at the transition from the supercritical to the subcritical state. At the same time tin –tungsten pegmatites are a

function of the geodynamic setting and the magmatic intrusive rocks generated in this setting (Table 3). Generally speaking, pegmatitic rocks are a mixtum compositum of crustal and subcrustal processes. An index element typical for subcrustal magmatic processes in the Sn–W pegmatites is sodium, the accumulation of which resulted in the formation of albitites — Sections 4.1.2 and 5.2. Albitization took place as a result of a Na-bearing � uid to be exsolved at the end of the pegmatite evolution in the East African Rift System (Vandaele et al., 2012). Albitite-type uranium deposits are exclusive to Proterozoic metamorphic rocks. A reference example lies within the Kirovograd-Krivoi Rog district, where deep-penetrating faults extend over several tens of kilometer and closely associated with pegmatite intrusions (Belevtsev, 1980; Grechishnicov, 1980). An example much closer to the anorogenic

Table 6

Boron-bearing minerals to be exploitedas gemstones from pegmatites and pegmatite-related skarns. Achroite (var. Elbaite) Axinite Danburite Datolite Dravite Dumortierite Elbaite Elbaite-Paraiba Indicolite Jeremejevite Kornerupine Liddicoatite Painite Rossmanite Rubellite Serendibite Sinhalite Verdelite

NaLi2.5Al6.5(BO3)3Si6O18(OH)4 Ca2MgAl2(BO3)Si4O12(OH) CaB2Si2O8 CaB(SiO4)(OH) NaMg3Al6(BO3)3Si6O18(OH)4 Al6.9(BO3)(SiO4)3O2.5(OH)0.5 NaLi2.5Al6.5(BO3)3Si6O18(OH)4 With Cu Na(Li,Al)3Al6(BO3)3Si6O18(OH) 4 Al6B5O15F2.5(OH) 0.5 Mg3.5Fe2+0.2Al5.7(SiO4)3.7(BO4)0.3O1.2(OH) Ca(Li,Al)3Al6(BO3)3Si6O18(O,OH,F)4 Ca0.77Na0.19Al8.8Ti0.19Cr0.03Zr0.04B1.06O18 LiAl8Si6O18(BO3)3(OH) 4 Na(Li,Al)3Al6(BO3)3Si6O18(OH) 4 Ca2Mg4.5Al1.5Si3.6Al1.8B0 MgAl(BO4) NaLi2.5Al6.5(BO3)3Si6O18(OH)4

Sn–W pegmatites from Brazil can be reported from Lagoa Real, Bahia (Lobato and Fyfe, 1990). It is not the only one located at the eastern sea border of Brazil (Espinharas, Itataia). The analogue beyond the Atlantic Ocean is Kitongo, Cameroon, which marks the initial suture zone for the opening of the Atlantic Ocean, a guide line for the mantle plumes sparking the pegmatite intrusion. One of the oldest granite pegmatite-hosted Sn deposits (Be–REE–Th– B–Li–Nb/Ta–Sn pegmatite (spodumene + Li mica)) is located in the Achaean Sinceni pegmatite � eld of the Kaapvaal Craton, Swaziland. It gave an age of 3000 Ma and has the highest concentration of cassiterite in the late-stage pegmatite units of sugary albite, associated with micatourmaline metasomatic selvages in the host rock (Trumbull, 1995; Cairncross, 2004). The � rst author interpreted the albitic parts of this granite pegmatiteas the products of late residual melt, andthe metasomatic selvages to re�ect �uid exsolution from the melt at the latest stage of pegmatite consolidation. The term granitic pegmatite would not well � t here. According to Trumbull (1995), the best tin values occur in pegmatites that exhibit boudinage and other signs of ductile deformation caused by shearing. Albitization and wall rock alteration are synkinematic. Further indicator rocks for a mantle impact on the formation of pegmatites may be seen in the ma�c rocks associated with the S-type granites. The Sn–W pegmatites are transitional from an ensialic to an ensimatic (rift-type) environment (Fig. 6a, b, Table 3). 4.2. Beryllium pegmatites (14 ABDEJ)

Beryl is a relatively rare element in theuppermost part of the continental crust averaging 3 ppm Be, where granites and pegmatites are the dominant igneous host rocks. Other than Sn and W which are accommodated in pegmatitic rocks in the lattice of a few true ore minerals such as cassiterite, wolframite and scheelite, Be is present in pegmatites in ore minerals such as beryl, being the source of beryllium and in a wide range of colored gemstones, with one of them, emerald, belonging to the “Big Three ”. Only a few of these gemstones which are very popular also with non-mineralogists for their esthetic value are mentioned here in this study devoted to the geology of pegmatites and shown in Fig. 10a, and Table 4. Ordinary chrysoberyl is yellowish-green, transparent or translucent. Alexandrite is strongly pleochroic of emerald green, red and orangeyellow colors which change under arti �cial light. Beryl has been given different names corresponding to its color: emerald (green), aquamarine (pale blue), heliodor (yellow), goshenite (transparent colorless variety), morganite (pink), rosterite (pink) and bixbite (red) (Fig. 10b, c, d).The pegmatite-relatedBe deposits,mainly of interest for the gemologists, were grouped in the “ Chessboard classi�cation scheme of mineral deposits ” into beryl –emerald–euclase– hambergite (14 a D), pegmatites, chrysoberyl and beryl-bearing pegmatites in the contact zone to metaultrabasic and metapelites (14 b A), chrysoberyl pegmatites (14 c E) and beryl pegmatites (14d D) (Dill, 2010).

463

H.G. Dill / Ore Geology Reviews 69 (2015) 417 –561 Table 7a

Table 7b

Fluorine-bearing pegmatites by country and geology – see also Fig. 18a as a 2-D representation – worked for �uorine-bearing minerals of gemological quality (modi �ed from Dill and Weber, 2013). For legends see Fig. 10a.

Boron-bearing pegmatites by country and geology – see also Fig. 18b as a 2-Drepresentation – worked for boron-bearing minerals of gemological quality (modi �ed from Dill and Weber, 2013). For legends see Fig. 10a.

No.

Site

Country

Mineral

No.

Site

Country

Mineral

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34

Altai Aracuai Baja California Lana Mine, Ouro Preto, Minas Gerais Caxias Chipata Gone — Shirgar Valley Goriko Zuun Bayan Guangdong Guangxi Hushe Hyakule Jos Katlang Ghundao Hill Limoeiro Loc Tan Marambaia Miass Naegi Niyit-Bruk Nyet Orivesi Phakuwa Schneckenstein Serro Shengus Spitzkopje St. Ann's Hurungwe District Stak-Nala Suishoyoma Virgem Da Lapa Voi-Taveta Xilin Qagan Obo Yunnan

Russia Brazil Mexico Brazil Brazil Zambia Pakistan Mongolia China China Pakistan Nepal Nigeria Pakistan Brazil Vietnam Brazil Russia Japan Pakistan Pakistan India Nepal Germany Brazil Pakistan Namibia Zimbabwe Pakistan Japan Brazil Kenya China China

Topaz Topaz Topaz Topaz Topaz Topaz Topaz Topaz Topaz Topaz Topaz Topaz Topaz Topaz Topaz Topaz Topaz Topaz Fluorite Topaz Topaz Topaz Topaz Topaz Topaz Topaz Topaz Topaz Topaz Fluorite Topaz Topaz Topaz Topaz

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Altai Alto Ligonha Anjanabonoina AraþuaÝ Aukas Baja California Black Mountain Dunton Mine Borborema Province Bortschowotschnom Brandberg Burmado Chipata Franciscopolis N Fianarantsoa Forrestania Fugong Gongshan Governador Valadares Hoh, Braldu Valley Hyakule Jequitinhonha Province Kantiwa-Ye · lya Karibib Kashmir Kef� Khumbu Klein-Spitzkopje Koktokay Korgal Korgal Laghman Kunar Province Kuortane KuruÚrte Lagham Province Luc Yen Lukusuzi Lundazi Mawi Mount Auburn Mount Mica Muiane Murupane Murrua Nacala Namecuna Nilaw Nuristan Pabrok Pala Paprok Paraiba Phakuwa Ramona Ribaue Rio Doce Province Rio Grande Do Norte Sahatany District San Diego County Talate Usakos Wah Wah Warriedar Tourmaline

Russia Mozambique Madagascar Brazil Namibia Mexico USA Brazil Russia Namibia Brazil, Bahia Zambia Brazil Madagascar Australia–Western Australia China China Brazil Pakistan Nepal Brazil Pakistan Namibia India Nigeria Nepal Namibia China Afghanistan Afghanistan Afghanistan Finland China Afghanistan Vietnam Zambia Zambia Afghanistan USA USA Mozambique Mozambique Mozambique Mozambique Afghanistan Afghanistan Afghanistan USA (California) Pakistan Brazil Nepal USA Mozambique Brazil Brazil Madagascar USA China Namibia USA Australia—Western Australia

Tourmaline Tourmaline Tourmaline Tourmaline Tourmaline Tourmaline Tourmaline Tourmaline Tourmaline Tourmaline Tourmaline Tourmaline Tourmaline Tourmaline Tourmaline Tourmaline Tourmaline Tourmaline Tourmaline Tourmaline Tourmaline Tourmaline Tourmaline Tourmaline Tourmaline Tourmaline Tourmaline Tourmaline Tourmaline Tourmaline Tourmaline Tourmaline Tourmaline Tourmaline Tourmaline Tourmaline Tourmaline Tourmaline Tourmaline Tourmaline Tourmaline Tourmaline Tourmaline Tourmaline Tourmaline Tourmaline Tourmaline Tourmaline Tourmaline Tourmaline Tourmaline Tourmaline Tourmaline Tourmaline Tourmaline Tourmaline Tourmaline Tourmaline Tourmaline Tourmaline Tourmaline

4.2.1. Be pegmatites in the Variscan Metallotect

A closer look at the map drafted by Štemprok (1981) for the European Variscides that illustrates the distribution of so-called granitophile elements such as Sn, W, Be, Li and U reveals a relatively high content for beryllium in the Moldanubian realm of the French part of the Variscides. The Moldanubian zone, also called the central geodynamic or core zoneof the Mid-European Variscides,includes two tectonostratigraphic units, one named as Moldanubicum sensu stricto forms the autochthonous unit, while the other allochthonous unit is named the Teplá– Barrandian zone or Bohemicum (Weber and Behr, 1983) (Figs. 2a, 9f). An overview of this geodynamic zone has been given by Matte (2001) and Raumer et al. (2003). The Moldanubian zone represents a stacked pattern of nappes which were superimposed onto each other during the late Variscan (Fig. 9f). Several Be occurrences are known from NW France. At MenezGoaillou-en-Coray in Finistère-Brittany, France, a typical “pneumatolitic – pegmatitic” beryllium mineralization with greisen, pegmatites and quartz veins, as they were described also f rom Great Britain, formed in the cupola of an aplitic granite, intruded into Brioverian schists ((P –As –Cu) –Sn –Be granite pegmatite). The mineralization is also enriched in As and Mo (Chauris and Le Bail, 1959). At ScaërLangonnet and Gouesnach aplites and pegmatites hosting beryl, bertrandite and tourmaline are associated with leucogranites of the Amorican Massif (Chauris, 2008, 2009). In the pegmatite at Monts d'Ambazac (Haute-Vienne) which is also associated with leucogranites, beryl was concentrated, as it was the case at Vieux Mayres (Le Château pegmatite) –P–B–Be granite pegmatite and at Imbert pegmatite at Montbrison in the Rhône-Alpes (Lebocey, 2008). All of these deposits and mineral showings have to be

grouped as granitic aplites or pegmatites with a strongly varying morphology. Stussi (1989) who dealt with the chemistry of granitic rocks of the French Variscides, classi�ed the granitic suite into three principal associations: aluminopotassic, subalkaline, and calcalkaline. Each of these associations is characterized by the petrographical and geochemical composition of their members and the nature of the related mineralization. Aluminopotassic granitoids contain most of the observed Sn, W, and U mineralization and

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Table 8

ANNW–SSEtransectthroughthe CentralEuropeanVariscidesand theAlpineMountain range with thepegmatiticrocksat varioussitesarrangedas a functionof thegeodynamicevolution of both orogens. Feldspar andquartz areonly mentionedfor theso-calledbarren or nonrare-elementcontaining pegmatitesand aplites, e.g.The “Host rocks” refer to therocksgivinghost to the pegmatitic and aplitic rocks. The “Chemical/mineralogical quali�er” and the “Type” are used according to the classi�cation scheme proposed in the CMS classi�cation but were arranged in decreasing order in this table for ease of comparison (the most prevailing element is placed on the left-hand side of the column). The “Geodynamic environment” summarizes the results of the geodynamic interpretations. The zone of Erbendorf –Vohenstrauss is equivalent to the Tepla–Barrandian Unit shown in Fig. 2a.


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Table 9

A comparison of Variscan-type pegmatites from the Central European Variscides (Hagendorf-South) with pegmatites from the Iberian Peninsula.

(continued on next page)

466 Table 9 (continued)



467

Table 9 (continued)

(continued on next page)

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Table 9 (continued)

all the Be, Nb –Ta, and Li mineralization. They are associated with two-mica leucogranites, with a separate occurrence of Sn, W, Li, Be, Nb –Ta mineralization related to highly evolved Na leucogranites, whereas U mineralization is related to K leucogranites. The author claims that the element distribution pattern which is also re �ected by the emplacement of pegmatites results from the ensialic evolution of the French Variscan orogeny and its granitoids were emplaced in response to the postcollisional thrusting and shearing tectonics — see also Fig. 9 for comparison. Moving eastward in the Vosges, France, and Black Forest Mts., Germany, we encounter basement blocks notoriously poor in elements known to be genetically related to granitic intrusions,such as Sn, Be, Nb or Li, even though almost half of the crystalline rocks exposed in the uplifted block of the Schwarzwald is made up of Variscan granites. The only granite-hosted mineralization bearing some Sn and Be and, hence, has beenmineralogically revisited again and again for its peculiar

position, is located in the Triberg Granite Complex, Germany (Markl, 1995; Achstetter, 2007). Analogous Be mineralization with bertrandite, phenakite and beryl has been known from the pegmatite veins at Rothau-Alsace, France on the opposite banks of the River Rhein/Rhin (Hohl, 1994). Besides a small tin mineralization, the author reported bertrandite, beryl, and phenakite from this granitic pegmatite. On the way East along the general strike within the European Variscides, these two massifs straddling the Upper Rhein/Rhin Valley Rift are the least endowed with rare-element pegmatites. The abundance of Be-bearing pegmatites and aplites signi�cantly increases as we approach the western edge of the Bohemian Massif. In the Moldanubian Zone, several pegmatites s.str. occur in marbles, calcsilicates, mica schists, cordierite–sillimanite gneisses, and granite– gneiss–mylonites, apart from granites and granodiorites. They contain beryl, bertrandite, bazzite, bavenite, helvine, bertrandite, and bityite and may be classi�ed as F–U–Be–Nb–P-, Be–B–P-, Sc–Li–F–B–U–REE–

Table 10

Chemical composition of various types of pegmatitic rocks in and around the Hagendorf –Pleystein Pegmatite Province, Germany.

H.G. Dill / Ore Geology Reviews 69 (2015) 417 –561 Table 11

a. Chemical composition of “nigrine”.

Sph = sphalerite, po = pyrrhotite, U-pyr = uraniferous pyrochlore, Ti –Al–P–Fe ox = “leucoxene”+“limonite” + aluminum phosphates, I + A = inclusion plus alteration. Chemical results are given in wt.% (modi�ed from Dill et al., 2014a,b).

Be–P- and B–Be–P pegmatites, in the majority of cases of tabular shape (Dill, 2015). Heading further east into the center of the Bohemian Massif — see Fig. 2b for location, the Scheibengraben pegmatite, 1.5 km E of Maršíkov, a tabular Be –Nb pegmatite was emplaced in mediumgrained hornblende gneisses (Novák et al., 2003) (Fig. 2a). According to Novák (2005), the following chemical relations can be met in thepegmatites of the Moravo Silesian zone: B ≫ P + F, and Be ≫ Li. With respect to the paleofacies and element composition of pegmatites, this geodynamic unit at the SE boundary of the Bohemian Massif is a close match to the Mid-German Crystalline High (Fig. 2a). The Mid German Crystalline High forms part of a suture zone extending from Mexico to Turkey, resulting from the late Variscan closure of the Rheic Ocean which opened up during the incipient stages between Gondwana and Laurussia and taking a wide range of Paleozoic sediments sourced from Baltica and from Gondwana — see also the fragments in Fig. 3. In other word, itis a global structure into the mantle persisting over a long period of time during the geological past. In Germany, the Königshain — ((P–U– F–Ag–Li–Sn–W–Pb)–Bi–Nb/Ta–Be–REE pegmatite is another member of this type of pegmatite (Thomas et al., 2009b). The area is endowed with lamprophyres a group of hypabyssal porphyritic rocks with phenocrysts of dark-colored minerals, whose lithological classi �cation scheme has not yet found common consensus and whose origin is still under debate (Seifert, 2008;Vasyukovaet al., 2011). Yetthere is littledoubt about their start-up from a subcrustal level and association with pegmatites in the Bohemian Massif (Dill,2015). A closer look at the increase of Be contents during fractionation of granites and the Be contents in lamprophyres reveals that the latter ma�c magmatic rocks come close to a highly differentiated granite as far as the Be contents are concerned. Richter and Stettner (1979) published the increase of beryllium by differentiation of a granite suite in the Saxo-Thuringian zone of the Mid-European Variscides: G 1: 4.6 ppm Be, G 2: 7.7 ppm Be, G 3: 9.9 ppm Be, G 4: 17.6 ppm Be (G 1 is the oldest granite and G 4 the most strongly fractionated granite). Seltmann et al. (1998) reported Be contents from the Erzgebirge granites, which also host granitic pegmatites, in the range of 5.1 to 11.0 ppm Be. This chemical data are supported by the �nds of Be daughter minerals in �uid and melt inclusions in this study area of the Erzgebirge (Thomas et al., 2011). Lamprophyres have considerable Be contents and so stand out from the overall igneous rocks, by values of 10.6 ppm Be (Dill, 2015). Mineralized pegmatites s.str., however, may reach up to 42.1 ppm Be, as at Plössberg, where beryllium formed minerals of itsownandberyl precipitatedas dominant rare element mineral. Across the Atlantic Ocean in the USA, remarkable concentrations of beryl, accompanied by amblygonite, spodumene and minerals of the triphylite s.s.s. were worked as a source of beryllium in South Dakota, in the Keystone District, and in Colorado. 4.2.2. Be pegmatites in the Alpine Metallotect

Threeareas deserve particular attention as to the reactivation of Late Variscan pegmatites in the course of the Alpine orogeny. It is from West to East, the Pyrenees, between Spain and F rance, the Alpine Mts. in SE

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Austria and the Western Carpathians in Slovakia, that is the eastern extension of the Alpine Mountain Ridge. All of them have pegmatites enriched in Be (Höller, 1959; Moser et al., 1987; Walter et al., 1990; Taucher et al., 1992, 1994; Malló et al., 1995; Uher et al., 2012 ). The Pyrenees form the westernmost part of the Alpine orogen with the majority of their rocks subjected to Late Cretaceous through Paleogene structural deformation (Alvarado, 1980). Granite-related, mainly skarn deposits, formed during the Paleozoic in the basement rocks of this Alpine mountain chain. Malló et al. (1995) described from the Albera Region zoned pegmatite in the Eastern Pyrenees, France. It is according to the CMS scheme a series of (Nb/Ta–U)–Be–Li–P pegmatites with chrysoberyl and Nb/Ta–Be–Li–P pegmatites with beryl. According to the authors, the individual pegmatite mentioned above is distributed within four subparallel zones, being arranged concentrically around anatectic muscovite–biotite leucogranites. In the main or central part of the Alpine mountain chain, geological investigations unraveled two major tectonic activities similar to the western Pyrenees, one during the Cretaceous and another during the Paleogene and Neogene provoking that the latePaleozoic and Mesozoic rocks that were under the sea within the Neo-Tethys elevated over the sea level and transformed into the present-day high-altitude mountain ridge, stretching from Grenoble, France, to Vienna, Austria. In the western Alps crystalline basement rocks are exposed among others in the Gotthard and Aare Massifs, Switzerland (Trümpy, 1980). Rare-element pegmatites do not play a signi �cant part in this area, apart from some mineral shows which have been paid attention to by mineral collectors. Heading east, in the Tauern Window and the “Altkristallin ” (Old Crystalline Rocks), Paleozoic rocks are of more widespread occurrence Table 11

b. Silica-bearing pegmatites by country and geology – see also Fig. 32e as a 2-D representation – worked for silica-bearing minerals of gemological quality (modi�ed from Dilland Weber, 2013). For legends see Fig. 10a.

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and pegmatites become more prominent constituents among the crystalline rocks, particularly in the Austrian Alps (Tollmann, 1977). The minerals of the Austrian pegmatites have been investigated for decades by different geologists (Höller, 1959; Moser et al., 1987; Walter et al., 1990; Taucher et al., 1992, 1994 ). A varied spectrum of beryllium minerals is known from the Koralpe pegmatite deposit: Uralolite [Ca2Be4(PO4)3(OH)3·5H2O], hydroxyl-herderite [CaBe(PO 4)(OH)], roscherite [(Ca,MnFe)Be2(OH/PO4)·2/3H 2O], weinebeneit e [CaBe3(OH)2(PO4)2·4H2O], beryl/aquamarine [Be3 Al2Si6O10] and bavenite [Ca4Be2Al2Si9O24(OH)2]. Beryl is among the minerals of the primary pegmatite mineralization and, hence, allows this primary pegmatite mineralization to be classi �ed as a B–Nb/Ta– Be–Li–P pegmatite based upon the mineralogical investigations of Niedermayr and Göd (1992). The primary pegmatite mineralization is analogous to that of the major pegmatite stocks exposed in the Hagendorf –Pleystein Pegmatite Province in the Moldanubian Zone towards the North of the Alpine Mountain Range (Dill, 2015). Thöni et al.(2008) were able to �ne-tune their previous petrological and chronological investigations and furnished clear evidence for a multiple emplacement ofthe pegmatiticmelts between 273 ± 2 and 258 ± 3 Ma, in some sites with offshoots even younger with anage downto 251 ± 7 to c. 230Ma. Ensuingoverprinting metamorphic processes under eclogitefacies conditions with peak temperatures around 700 °C and a pressure at 2.2 GPa accompanied by an intense deformation during Cretaceous time, were unable to obliterate previous isotopic signals and to blur the magmatic nature of the aforementioned rocks. In the Western Carpathians beryl is the characteristic mineral of the Variscan (ca. 350 Ma) pegmatite dikes of the Tatric Unit (Uher et al., 2012). Accessory Nb–Ta–(Sn)oxide mineralsoccur in the mostfractionated ones. According to the authors 1st gen. beryl is associated with the K feldspar, while the 2nd one is found in the saccharoidal and cleavelandite albite unit of the pegmatites. On comparison of VariscanBe-bearing pegmatites in Alpine orogens, thethree reference typesfrom thevariousbranches have onemineralin common, beryl. It is the primary beryllium mineral that developed within the Paleozoic source rocks. According to Barton (1986), in a water saturated system above 600 °C, beryl reacts with one of the

Al2SiO5 polymorphs to produce chrysoberyl, which was obviously the case in the pegmatites of the Pyrenees. Around 200 °C phenakite and bromellite hydrate to bertrandite and behoite, respectively, and pure beryl reacts to euclase + quartz + bertrandite or phenakite. This mineral association supplemented with some Be phosphates is characteristic of the Austrian pegmatites and attests to an adjustment of the primary Be mineralization to the late-stage hydrothermal condition. In theCarpathian Mts. Uher et al. (1998) describedseveral pegmatites such as the Variscan Prašivá pegmatites as rather primitive Be-bearing pegmatites. They suffered only modest alteration upon the Alpine reactivation or in other words were incorporated into the modern fold belt without any signi�cant mineralogical and chemical changes. Another type, not very widespread in the southern Bohemian Massif was studied by Novák andFilip (2010). Itis presented bytheKožichovice II pegmatite which apart from its high beryllium contents is also outstanding as to its exotic Be mineralizationwithberyl,bavenite, andbazzite andthereby furnish evidence of a close genetic link to the ultrapotassic orogenic Třebíč syenogranite, Czech Republic. The exotic Be mineral association with smectite came into being at temperatures slightly below 250 –350 °C with neutral to slightly alkaline conditions accountable for the formation of the secondary mineral assemblage encompassing beryl II, bavenite, bazzite plus smectite.This rare type of Variscan Be pegmatite has no analogue within the Alpine-Carpathian mountain chain. 4.2.3. Be pegmatites in the Proterozoic Metallotect in Africa

Beryllium minerals are common to many pegmatites in Africa, where they provide a good basis for small-scale miners and local diggers who exploit the colored varieties of beryl and its associates to make their living from (Fig. 10a). This is especially true for Madagascar, today an island separated from Africa and India by the Indian Ocean and during the Precambrian was squeezed between Africa and India (Fig. 3). Geodynamically it is located at the southern end of the Mozambique Belt, where syntectonic (750–600 Ma) and post-tectonic pegmatites developed (Petters, 1991). The younger pegmatites, straddle the Precambrian-Paleozoic boundary around 565 Ma down to 492 Ma (Berger et al., 2006; De Vito et al., 2006 ). Apart from Be, the pegmatites on the Isle of Madagascar contain increased amounts of U, REE, Nb and

Table 12

Processes leading to the emplacement and alteration of the pegmatites and aplites in the Hagendorf –Pleystein Pegmatite Province, Germany (modi�ed from Dill, 2015).


Ta (De Vito et al., 2006; Knorring von and Condliffe, 1987 ). Pezzotta (2001) tried to adjust the existing classi�cations and created a new scheme with three classes (1) abyssal class, (2) rare element class, (3) NYF miarolitic class. I mention this scheme only for the sake of completeness and to highlight the importance of beryllium among the group of elements relevant for the pegmatites. A list of gemmy berylliumbearing minerals is presented in Table 4 and shown in Fig. 10. Pezzotta (2001) listed beryl–columbite-, beryl–columbite–uranium-, beryl–columbite–phosphate-, chrysoberyl/massive + miarolitic, and emerald pegmatite subtypes under the header beryl. The study is very detailed but the classi�cation scheme is still inconsistent in each structure and applicable only for the sites under study. Some beryllium-bearing pegmatites are shown in the paragraphs below. The Mananjary emerald district hosts (F–B–P–Mo)–Be pegmatite (emerald) whose emeralds formed along a phlogopitic contact zone between the pegmatite and the surrounding basic to ultrabasic igneous rocks (Cr-rich meta-ultrabasites (hornblendites) which can be held accountable for the vanadium being the chromophore of the beryl) (Grundmann, 2001; Groat et al., 2008). According to Moine et al. (2004) who studied � uid inclusions in the metasomatic minerals, the alteration took place at 500 °C and 2 kbar. Coprecipitation of F-rich phlogopite caused the deposition of beryl (Moine et al., 2004). Vapnik et al. (2006) reported a temperature and pressure regime of 250 to 450 °C and 1.5 kbar based upon �uid inclusions in emeralds from the Kianjavato deposit in the Mananjary region and postulated shearing was the mechanism most relevant for introducing a CO2-rich �uid to foster the emerald genesis at the Kianjavato deposit. The Isahara Pegmatite Field was described by Pezzotta (2001); it contains B –F–Be pegmatites (aquamarine). Moreover these pegmatites host topaz, tourmaline, smoky quartz and citrine and are intercalated into migmatitic rocks. The reason why these pegmatites are pigeonholed as NYF, being devoid of Nb, Y and HREE minerals is not known. Pegmatites in the Ambatondrazaka district, Madagascar, e.g., near Masiadrivotra are Be pegmatites (chrysoberyl) or B–Be pegmatites (chrysoberyl–beryl/tourmaline –dumortierite) and said to be bound to granites (Behier, 1960). The geodynamic palimpsest map of Gondwana in Fig. 3 gives a location totally different from Madagascar's present position just to the East of Mozambique. It was located then near the “Horn of Africa”, where the Kenticha and Bupo pegmatites in Ethiopia contain beryl besides Nb/Ta oxides, spodumene, and amblygonite (Tadesse and Zerihun, 1996; Küster, 2009). The Be-bearing pegmatite at Kenticha, Ethiopia, is a peraluminous pegmatite bound to a post-accretionary granitoid magmatism, lasting from 610 to 530 Ma (Küster, 2009). The author renders I-type or A2-type magmas accountable for the mineralization in the pegmatites with either crust derived or hybrid crust –mantle derived magmas. Kenticha,Ethiopia is a (Sn)–Be–Li–Ta tabularpegmatite (Li silicate N Li phosphate). Beryl occurs as emerald, and lithium is accommodated in lepidolite, spodumene, holmquistite, elbaite and swinfordite, while Li phosphates are represented by amblygonite and lithiophyllite, so that a simple description as spodumene type would not � t in. This classi�cation is only true for the Bupo pegmatite. The Ethiopian pegmatite province bears beryllium only as minor constituent besides Ta and Li manifesting closer chemical similarities with Greenbushes, Australia, than the pegmatites in Madagascar — see also the geodynamic attribution of elements in Table 2 and Fig. 6b. Magadascar's pegmatites feature stronger Rift-type af �liation than the Ethiopian ones already signaling a break-away tendency from the African continent which only took effect during the late Mesozoic when it split from Africa around 150 Ma and from India 90 Ma ago, while Ethiopia is still �xed to the main continent. In the Alto Ligonha Province, northern Mozambique, the situation is not any better in the Li- and Nb/Ta-bearing pegmatites, where beryl is only an accessory mineral in the K-enriched pegmatites (Schmidt, 1986; Cronwright, 2005; Thomas and Davidson, 2010). Even in the renown Bikita pegmatite beryl is present only in subordinate amounts

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and was investigated as to its trace element contents by Černý et al. (2003). Pegmatite-related schist-hosted emerald deposits are mined in open pits in Zambia (Fig. 11). Seifert et al. (2004) gave a detailed account on the origin of the emerald deposits in the Kafubu Area, Zambia. The authors identi�ed highly magnesian talc –chlorite ± actinolite ± magnetite metabasites, hosting emerald mineralization as metamorphosed komatiites. A closer look at Fig. 38e cited in context with the hydrothermal kaolinization of pegmatites provides a picture similar to the photograph taken in Zambia. In the Ural Mts. emerald developed at the contact between granite and talc schists plus talc – actinolite schists (Fig. 38e) (Fersmann, 1929). The pegmatite hosting the emerald pockets is associated with albitites and was affected by a strong hydrothermal kaolinization (see also Section 5.2 about episyenitization and albitization). The felsic melt of the pegmatites interacted with the Cr-bearing basic country rocks. As a result of this desili�cation of the pegmatites part of the rocks were converted into albitites (see also Section 5.2 about episyenitization and albitization). One of the classical emerald and alexandrite mining areas in pegmatites ((P–Li–B–Bi–Mo–Nb–Ta–F)–Be pegmatites) and also the main source of industrial beryllium was the Izumrudnye Kopi area, near Ekaterinburg intheMiddleUrals,Russia, where more than 35sitesof berylliumconcentration were found in an area measuring 25 × 2 km (Pekov, 1998). 4.2.4. Synopsis of Be pegmatites

The pegmatite-related Be-bearing gemstone deposits were extracted from the global distribution of Be-bearing gemstones (Dill and Weber, 2013) (Fig. 10a). The newly created map allows for delineating two areas, which have already attracted our attention as we dealt with the Sn–W deposits in Section 4.1. It is the East Africa Rift System and the suture zone betweenBrazil, Namibia andNigeria. Many small-scale mining operations are known from eastern Africa and from Brazil. While other beryllium concentration, e.g., in the Variscides did not bring about precious beryl from aquamarine through morganite, these deep-seated sutures gave rise to such an accumulation of Be and sparked small-scalemining. There is one site outstanding for the concentration of precious beryl, where the element creating the host, beryllium, and the chromophores, e.g., vanadium and chromium, contained in basic and ultrabasic rocks from the mantle comes close to one another like nowhere else on earth. Madagascar is rife with Be-bearing pegmatites and host of the 3rd largest known deposit of vanadium in the world. The Green Giant vanadium deposit was discovered in 2007 at the southern tip of the Isle of Madagascar by Energizer Resources Inc. (Fig. 10a). Evensen and London (2002) performed experimental studies of the partition coef �cients for beryllium between hydrous granitic melt and alkali feldspars, plagioclase feldspars, quartz, dark mica, and white mica at 200 MPa H 2O as a function of temperature in the range of 650 to 900 °C. The experimental results and the interpretations published by both authors did not � nd a general consensus as demonstrated by Thomas and Davidson (2015) in their Fig. 4. Based on their experimentalresults and the interpretations,Evensen andLondon (2002) concluded that cordierite, calcic oligoclase, and muscovite (in this order) control as to whether Be get incorporated or not into pegmatites. Beryl-bearing pegmatites can develop only after extended crystal fractionation of large magma batches. All those magmas that originate from cordieritebearing protoliths or that contain large modal quantities of calcic oligoclase will not achieve beryl saturation at any point in their evolution. Another geodynamic setting abundant in rare element relevant for the formation of pegmatites was studied during �eld work in Central Mongolia. The Early Mesozoic Bogd uul, Tsagaan davaa and Modot granites of the Sn –W–As–Pb–Zn–Cu complexes of the Khentii Uplift, Mongolia, felsic intrusive rocks surrounded by a marginal facies of more granodioritic to monzonitic composition were attributed to the A2-type granites which evolved post-collisionally in an intracontinental environment (Dill and Khishigsuren, 2013). Siting of a few samples within the � eld of so-called collisional or volcanic arc granites is caused by alteration and can be excluded by � eld evidence

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from the discrimination diagrams. This geodynamic classi�cation is based on discrimination diagrams using K, Na, Si, Nb, Y and Rb (Fig. 12a, b, c). The basic x –y plot Y + Nb vs. Rb elaborated by Pearce et al. (1984) shows the majority of the granites to fall in the � eld of the within-plate granites (Fig. 12a). The pattern resembles the data arrays in the various discrimination plots drafted by Simmons et al. (2011) for the REE-rich pegmatites from sites in South Platte, Co, Trout Creek Pass, Co, Kingman and Aquarius Range, Az, USA. The chemical discrimination of plutonic rocks based upon the mol ratios using Al2O3, K2O, Na2O and CaO sheds some light on the aluminous character which is peraluminous for all samples excluding one (Maniar and Piccoli, 1989) (Fig. 12b). Based upon the diagram put forward by Le Maitre et al. (1989) a x–y plot with weight percentage of K 2O vs. SiO2, the granites classify as high-K granites (Fig. 12c). The rare metal granite system has also elevated contents of �uorite, topaz and tourmaline and is characterized by the LREE minerals allanite-(Ce) and monazite (Ce) prevailing over xenotime being the only host of HREE in these Mongolian granites. Beryllium shows non-correlation in these A-type granite system with all elements excluding the REE (r = 0.74) and Th (r = 0.54). Beryllium is another example forthe important role thesubcrustal magmas play in the formation of pegmatites together with REE elements. The separation of HREE and LREE may be due to �uorine complexing of HREE over LREE (Simmons et al., 1987). Based upon the regionaldata presentedabove,beryllium togetherwithstrong albitization is mainly observed in an extensional geodynamic region (rift-related) which may persist over quite a long time as shown by the examples from the African and South American continents. But it is also present in collisional and reactivated geodynamic settings (Fig. 6b). 4.3. Rare-earth element and zirconium pegmatites and pegmatite–skarns (24DE + 39 E)

Therare earth elements(REEs) arecurrently in thelime lights due to some shortage of supply for part of these element suite owing to some misbalances in the production of REE by leading countries: China (100,000 t), USA (3200 t), India (2300 t) and Malaysia (320 t) ( Weber and Zsack, 2007). China's share in the world REE production stands at 94% based on its giant REE deposit Bayan Obo, a non-pegmatitic REE concentration in Inner Mongolia. After years of controversial discussion, the pendulum on the concentration of the largest REE resource in the world has swung towards a carbonatitic origin including dolomite, calcite and calcite–dolomite carbonatite varieties as source rocks (Yang et al., 2011). The second and third in the row are no pegmatitic REE deposits either. Little workhas beencenteredon REEaccumulation in pegmatites. On the other hand a quick look at the REE deposits related to alkalineintrusive, effusive and carbonatitic, magmatic rocks which contain more than 50% by volume of carbonate minerals provide the reader with a series of rare elements very well known also from pegmatitic rocks, such as P, Nb, Ta, F, Be, ( Mitchell, 1991; Woolley and Church, 2005). Intra-plate fractures, grabens or rifts are settings not far away from the pegmatite-controlled REE deposits and processes relevant f or the emplacement and alteration of the above REE-bearingalkaline igneous rocks cannot be sidelined when dealing with pegmatite-hosted REE deposits (Fig. 13). Kanazawa and Kamitani(2006) listed about 200rareearth minerals. The most common ore minerals of REE are phosphates: Monazite, xenotime, ningyoite, � orencite and rhabdophane — see also Fig. 15c and d in the succeedingsection.They occur in metamorphicand granitic rocks andresultfrom supergenealteration andthusmay oftenbe metin pegmatites, albeit as accessory minerals only. Second most in abundance are REE carbonates such as bastnaesite, synchysite, lanthanite and parisite which are of widespread occurrence in carbonatites often accompanied by REE oxides, e.g., cerianite and knopite and REE niobates–titanates, e.g., fergusonite and aeschynite. The latter may also be encountered in or adjacent to pegmatitic deposits.

Owing to its close association with REE in pegmatitic rocks, Zr is dealt with together with this group of elements in Section 4.3. Zirconium and its “ closest chemical ally” hafnium are chemically next of kin to titanium but far less widespread than this major element and only present in the earth's crust at an average of 140 ppm Zr. Zircon is the most common representative among the Zr minerals. Yet there are some rare Zr minerals present in pegmatites, e.g., Strange Lake, Canada, which many of us probably never have heard of (Birkett et al., 1992). 4.3.1. REE pegmatites in the Variscan Metallotect

REE-bearing pegmatites are not as common as Li-, Sn- or P-bearing ones in the central Variscides. Only taking a look at the MoravoSilesian geodynamic unit to the East and South-East of the Central European Variscides may change our view. Some well-studied examples of REE-bearing pegmatites are located in the Třebíč Pluton which lies about 20 km to the West of Brno, Czech Republic, on the boundary between the Moldanubian and Moravo-Silesian Terranes (Škoda and Novák, 2007). Considering the mineral association reported by Škoda et al. (2006) and by Škoda and Novák (2007), the pegmatites have to be classi�ed as (W –Sn–F–Li)–Be–Nb/Ta–REE pegmatite dikes. The REE-hosts are monazite, xenotime as well as aeschynite- and euxenite-group minerals. The dikes reside in amphibole–biotite melasyenite to melagranite (durbachite) of the Třebíč Pluton. These ultrapotassic intrusive rocks were interpreted as a product of mixing of magmas derived from the mantle and the crust ( Janoušek et al., 2000). These ultrapotassic intrusive rocks, called durbachites were also recorded from the Black Forest and the Vosges Mts., yet without any link to pegmatites there (Holub et al., 1997). At Oslavice near Velké Mezíříčí in the Třebíč Pluton in some mineral sites allanite-(Ce) acts as host of REE in a REE pegmatite-dike pertaining to the syenogranite shoshonitic association (Škoda et al., 2006; Škoda and Novák,2007). From anothersite at Oslavice,the authors reporteda mineral assemblage conducive to a Nb/Ta–Be–REE pegmatite-dike-pocket. In both cases, the host rock lithology closely resembles that described from the within-plate granitic system illustrated in Fig. 12c. Heading for the gneiss in the country rocks of the Třebíč Pluton causes a change in the structure and in the composition of the pegmatite: Sn –F–Li–B– Nb/Ta–Be–REE (Li tourmaline –Li mica) (Novák et al., 1999a,b). Some more pegmatites have been classi�ed and placed here as a function of host rock lithology to demonstrate the close relationship between geological setting and the type of pegmatite: Bližná I (Li–P–W–Nb/Ta)–B– REE pegmatite-dike (metacarbonate) (Novák et al., 1999a,b), Vlastě jovice near Zruč nad Sázavou (F–P–As–Sn–U)–Nb/Ta–B–REE pegmatite dike-layers (migmatites–gneiss–skarn) (Novák and Hyršl, 1992; Žáček et al., 2003; Ackerman et al., 2007), Ruda nad Moravou (P–Zr–U– Th)–Nb/Ta–REE pegmatite dike (ultrabasite) (Novák and Gadas, 2010), Maršíkov I and III (Zn) –REE–Nb/Ta –Be metapegmatite (Černý et al., 1992). Also from the eastern boundary of the Bohemian Massif, REEbearing pegmatites are known at Szklarska Poręba (Karkonosze Massif, Lower Silesia, Poland) (Szełęg and Škoda, 2008). In the StrzegomSobótka Massif, miarolitic pegmatites were encountered in the twomica monzogranite whose age of formation was chronologically constrained to 324 ± 7 Ma by Pin et al. (1989). The various minerals allow for an attribution of this pegmatitic mineralization to a REE –Nb– Ta–Be–B–Sc–F–W granitic pegmatites miarolitic ( Janeczek and Sachanbiński, 1989; Ciesielczuk et al., 2008 ). Another lens-shaped and zoned pegmatite called Skalna Brama pegmatite is located near Szklarska Poręba within the Karkonosze Granite. It is a As –Nb/ Ta–U–REE–pegmatite containing zirconolite, gadolinite, fergusonite – formanite, aeschynite, arsenopyrite, uraninite, monazite, zircon, and xenotime (Szełęg and Škoda, 2008). In the same geotectonic setting at the eastern edge of the European Variscides near Königshain a (P –U– F–Ag–Li–Sn–W–Pb)–Bi–Nb/Ta–Be–REE pegmatite miarolitic was investigated by Thomas et al. (2009b). The CMS classi�cation schemeis more suitable for a �ne-tuning of the source of pegmatitic rocks in the


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Variscan Orogen than the current classi�cation schemes, allowing you to closely link REE-bearing pegmatitic rocks with deep-seated lineamentary fault zones and thrust zones along the edge of uplifted basement blocks and to estimate to what extent crustal material has been involved in the built-up of the pegmatites, simply by considering the elements listed in Fig. 6b. The Třebíč Pluton bears pegmatitic deposits from pure mantle-controlled Nb/Ta–Be–REE pegmatite-dikepockets through Sn–F–Li–B–Nb/Ta–Be–REE pegmatite (Li tourmaline – Li mica). The � rst-order ore control is executed by the structure, the second-order control by the host-rock-lithology. Frequently, U and Th are close by, a fact that may make mineralogists enthusiastic for the number of minerals awaiting study andthe potential for chronologically constraining the emplacement, but it does not make happy the entrepreneurs and engineers who have to get rid of the radioactive material under certain circumstances.

rapakivi granite, SE Finland (Lukkari et al., 2009). The Motzfeldt Sø REE deposit linked to the intrusion of the Igaliko nepheline syenite complex, contains important Ta–Nb enriched zones with pegmatite and diorite dykes, apart from the syenite (Tukiainen, 1988). In Scandinavia and Greenland the REE-bearing pegmatites are either bound to fractured granitoids or closely linked to alkaline igneous rocks of subcrustal derivation.

4.3.2. REE pegmatites in the Alpine Metallotect

4.3.4. REE pegmatites in the Proterozoic Metallotect in Africa

A series of syngenetic and epigeneticpegmatites quite differentfrom those described in Section 4.2.2 evolved in the granodioritic –tonalitic Masino-Bregaglia intrusion, and within the Alpine Lepontine nappe boundaries in close contact with the Insubric Line (Guastoni, 2012; Guastoniand Pennacchioni, 2013). The Masino-Bregaglia intrusive massif is Oligocene in age. Thepegmatitic rocks areNb/Ta–Y –U–REEpegmatites. Guastoni and Pennacchioni (2013) gave an account of some more low-evolved pegmatites in the SouthernAlps thatmay be categorizedas (Li)–B–P–Be metapegmatites within orthogneiss and were affected by strong albitization, while other pegmatites reside in tonalites and granodiorites. Syngenetic pegmatitic rocks formed in a rather “hot” environment of temperatures greater than 450 °C, whereas the epigenetic true pegmatites show all hallmarks of strongtemperature contrasts in a “cool ” environment with sharp contacts and aplitic apophyses. The above authors postulated that the syngenetic metapegmatites formed intheinterval32to25Ma(Liatiet al., 2000; Oberli et al., 2004).Theepigenetic aplites and pegmatites were emplaced in the age interval 32 to 24.1 Ma (Gebauer, 1999; Guastoni and Mazzoli, 2007 ). Guastoni and Pennacchioni (2013) feel hard pressed to � nd a parental granite exposednearby, which does not exist and consequently pointto themetamorphic processes as the stimulusfor the pegmatitization. Theyexplain the emplacement of these pegmatites in a wide range of non-granitic host rocks by an increase of the temperature during metamorphism, in that metamorphic temperatures can remain above solidus (650 °C) for a long time, as it is the case with the Lepontine dome. The REEand Be-bearing pegmatites,some also contain the beryl variety emerald amongtheir accessory minerals,formed in thewaning stages of thecollision between the Adriatic microplate and the Europeanone during the passage from the Eocene to the Oligocene. They re �ect the mantlederived component of mobilization and metasomatism (formation of emeralds) during these plate tectonic processes whereas the minor amount of P, B and Li is interpreted in terms of the crustal input into this mixed-type or complex pegmatite system. The synkinematic through post-kinematic features observed by the authors well � t into thescheme of geodynamic evolution at that time of theAlpine Orogeny.

The pegmatites on the Isle of Madagascar are also well endowed with REE apart from Nb/Ta, U, and Be (Delbos, 1965; Berger et al., 2006; De Vito et al., 2006). The youngest members of these pegmatites reside within the Pan-African mobile belt which extends from the eastern Desert, Egypt, down to Mozambique and swings into the eastern appendix of Africa, Madagascar (Schmidt and Thomas, 1990; Fung et al., 1990; Fritz et al., 2013 ). The youngest pegmatites yielding a monazite age between 554 and 492 Ma according to Berger et al. (2006) are most strongly enriched in REE. The zoned Mboro (B)– Bi–REE–Nb/Ta pegmatite, in the eastern Atsinanana Region, Madagascar, produced large quantities of samarskite-(Y) besides columbite–tantalite group minerals (Giraud, 1956; Besaire, 1966). The Ikalamavony Pegmatite Field, in the Matsiatra Region, Madagascar, with its (W–REE–Bi)–Be–P–Li–Nb/Ta pegmatites contains also REE mainly accommodated in the lattice of minerals like xenotime and to subordinate amounts also in pyrochlore-group minerals (Giraud, 1957; Pezzotta, 1999, 2001 ). Across the Canal de Mozambique, which is part of the Indian Ocean, in Mozambique, REE-bearing pegmatites are still common as shown by theREE–U pegmatites of the Mavusi, TeteProvince, Mozambique,located in a syenitic and gabbroic environment. Uranium and LREE are accommodated in a typical refractory mineral davidite-(La). In the Marropino deposit, Alto Ligonha Province, (REE –Bi)–Li–F–Be–Nb/Ta pegmatites have been reported by Schappmann (2005). Rare earth elements are present although of subordinate quantity in the Alto Ligonha Province in a series of (U –Th–REE)–Be–Nb–Ta–Li pegmatites (spodumene–lepidolite) which were emplaced during the waning phases of the Pan-African Deformation (Dias and Wilson, 2000; Schäfer and Arlt, 2000; Thomas and Davidson, 2010). Heading further north along the Pan-African Metallotect no outstanding REE concentrations can be re ported anymore. Minor amounts of REE are also found in the Kobokobo (B–Sn–REE–Li–As–Th)–P–U–Be–Nb pegmatite, DR Congo (Sa�annikoff and van Wambeke, 1967; Van Wambeke, 1987). On the opposite side of today'sAfrica, the Etiro (Cs–REE–Bi–B–Li– Nb/Ta)–P pegmatite, in the Karibib District, of the Erongo Region, Namibia, bears monazite (von Bezing et al., 2008) (Bi)–Nb–Ta–Sn– Be –Li –P pegmatite (LiS − LiP). At Odegi, Nigeria, in the Afu Hills (Th–Sn–Nb/Ta)–REE pegmatites (LREE-carbonate N LREE phosphate) characterized by a strong albitization occur (Styles and Young, 1983). The REE hosts are bastnaesite-(Ce), bastnaesite-(La), cerianite-(Ce), �uocerite-(Ce) and monazite-(Ce). The location cannot precisely been given and the age relation only constrained by the chemical composition which points to an af �liation with the anorogenic Younger Granites. They were intruded during the Jurassic into the Precambrian gneiss–migmatite complex in the course of the incipient spreading of the Atlantic Ocean or more precisely as the rifting in the Benue Trough took place (Mücke and Neumann, 2006; Woolley, 2001a,b). Crossing into eastern Brazil means that the wheel has come to full circle in the southern Gondwanaland as to the emplacement of pegmatites (Fig. 3).

4.3.3. REE pegmatites in Greenland and Scandinavia

While in Central Europe none of the pegmatites has been explored for its REE contents, a case in point may be reported from the Näverån Th–(U)–REEdeposit, in western central Sweden. The fracturebound mineralization in weakly deformed granitoids has REE-bearing minerals such as xenotime-(Y), monazite-(Ce), allanite and an Y-bearing phosphate togetherwith uraninite (Sadeghi et al., 2013). Criss-crossingstockwork-like REE–Nb/Ta pegmatite veins (fergusonite –euxenite) at Dusserud, South Sweden, are held to be related to the Blomskog Granite, Sweden (Fig. 8o). The gneisses at Dusserud, South Sweden, are dated to 1.65 Ga. By contrast, zirconium may improve the quality of the ore given the mineralogical bonding is not too complex. This is true also for miarolitic Be–Nb/Ta–B–F–REE pegmatites with topaz and � uorite in the Wiborg

A complex REE-bearing mineralization has been discovered in the Two Tom Lake deposit that is hosted by the Letitia Lake Group metavolcanic rocks and associated metasyenites (Miller, 1988). Barylite, eudidymite, niobophyllite and pyrochlore, were suggested as possible REE hosts (Westoll, 1971). Results from drill holes have shown grades of as much as 1.32% TREO*, 0.37% Nb 2O5 and 0.23% BeO (Rare Earth Metals Inc., Press Release, November 17, 2010). The Y –Th–REE –Nb– Zr –Be mineralization is genetically related to peralkaline magmatic activity.

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4.3.5. REE pegmatites in the Brazilian Shield

In the Conselheiro Pena District the (Be–P–Sn–REE)–Nb/Ta–Li–B pegmatites (Li silicate) also contain a REE mineral assemblage (Wilson, 2012). The current data indicate that all rare element pegmatites in the eastern provinces are of Brasiliano age, i.e., formed between 600 and 480 Ma, which is contemporaneous with the Pan-African Orogeny in Africa, mentioned above in Section 4.3.4 (Morteani et al., 2000). Bastos Neto et al. (2009) investigated a complex deposit which indicates that these A-type mineralizations hosting REE are not con�ned to the PanAfrican or Brasiliano but have their onset much earlier around 1880 Ma. The Madeira deposit, in the Pitinga mining district, Amazonas State, Brazil is characterized by an association of Sn with cryolite, Nb, Ta (Y, REE, Li, Zr, U, and Th) in an albite-enriched granite that hosts a massive cryolite deposit. REE concentrations with xenotime are reported from the pegmatitic zones. Yttrium and REE mineralization includes gagarinite-(Y), with �uocerite-(Ce) inclusions that formed by exsolution of the early gagarinite. 4.3.6. Zr pegmatites

Zircon is a commonaccessorymineral in metamorphic, magmaticand even sedimentary rocks, where it appears in signi�cant amounts on account of its resistance to hypogene and supergene alteration, and even contributes to placer deposits of economic grade. In pegmatites it is not ubiquitous, but warrants mentioning for its diagnostic value when it comes to the origin of its host rocks (Fig. 14b, c., d). Pegmatite samples from calk alkaline and alkaline pegmatites show an almost isometric morphology, some are bipyramidal. The darkest almost black varieties of zircon are most strongly enriched in U, Th and REE (Fig. 14d). The Strange Lake pegmatite, Canada, is a (Li –Zn–Th–F–Nb–Ta)–Be– REE–Zr pegmatite–aplite formed in an alkaline magmatic province in Canada (Miller, 1990, 1996; Salvi and Williams-Jones, 1995; Kerr, 2010; Kerr andRafuse, 2012). Gysiand Williams-Jones (2013) provided a hydrothermal mobilization model to elucidate the �uid–rock interaction in the peralkaline granitic systems and provide and a clue to the concentration of REE and Zr. Many of the pegmatites are zoned into a border zone consisting primarily of K-feldspar, arfvedsonite, quartz, and zirconosilicates, and a core rich in quartz, � uorite and some exotic REE minerals. The primary silicate minerals in the pegmatites were replaced during acidic alteration by K-, Fe- and Al-phyllosilicates, aegirite, hematite, �uorite and/or quartz. Primary zirconosilicates (e.g., elpidite) were replaced by gittinsite and/or zircon. Secondary REE-silicates indicate hydrothermal mobilization of the REE. Hydrothermal �uorite and �uorite–�uocerite-(Ce) s.s.s. are interpreted to indicate the former presence of F-bearing saline � uids in the pegmatites. Mobilization of Zr took place at rather low temperatures around 250 °C, whereas the REEs were mobilized by saline HCl-bearing � uids at higher temperatures around 400 °C. The authors claim as a key requirement for REE and Zr mobilization in peralkaline igneous intrusions the formation of an acidic subsystem with high �uid/rock ratios that increases the overall permeability of the rocks. This alkaline mantle-derived magmatic system does not only assist in a better understanding of the simultaneous precipitation of Zr and REE in such a pegmatite, it also sheds some light on the concentration of �uorine (Section 4.5.2.1). There are numerous examples revealing the concentration of Be, REE, Ti, Ta, Nb, Zr and Hf in peralkaline magmatic rocks, e.g., Lovozero and Chibina, Russia, Mont Saint-Hilaire, Canada, and Ilímaussaq in South Greenland, as shown in the review by Dill (2010). In the case of peralkaline miaskitic rocks Zr and Hf are incorporated in minerals like zircon, sphene and ilmenite, whereas in agpaitic varieties, these elements form complex Na-(Zr, Ti)-silicates. Zircon concentrations are known from the nepheline syenite pegmatites in the southern part of Seiland Island, Norwayand from Mwanza, Malawi, which also belongs to thealkaline magmatic province in Eastern Africa.Bjørlykke (1934, 1937) was among the �rst to study the Swedish and Norwegian pegmatites which concentrated Zr and REE mineral during the initial phase of their emplacement.

The world's largest laccolitic alkaline magmatic complex at Lovozero, Russia, has revealed an extraordinary mineral association andlithology. During the Paleozoic, alkaline magmatic rocks intruded during a multistage process garnet –biotite– gneisses: (1) nepheline syenite, (2) rhythmites of alternating urtites, foyaites and lujavrites, (3) eudialyte lujavrite which were intruded into older rocks, (4) lamprophyre dykes. Nb ore occurs in seams of varying thickness and made up of loparite overlying pyrochlore ore. The mineral assemblage includes among others loparite (Nb–Ta–REEperovskite), murmanite (alteration product of lomonosovite), lomonosovite, eudialyte, lorenzenite and pyrochlore (Chakhmouradian and Sitnikova, 1999; Chakhmouradian and Mitchell, 2002; Pekov, 2000 ). There are various pegmatites such as Yubileinaya pegmatite, No. 61 pegmatite and the Palitra pegmatite (Pekov, 2005). Niobium is accumulated in the agpaitic nepheline syenite (7 Mt of metals), tantalum is concentrated in loparite layers in the agpaitic layered intrusion (80,000 t grade 500 ppm Ta), while zirconium is accumulated in the eudialyte-rich layers in agpaitic syenites and their pegmatites (210 Mt of metals, grade 1% Zr) (Kogarko, 1987 ). Within the 1.13-Ga-old Ilímaussaq intrusive complex, a magmatic assemblage of titanomagnetite + apatite + ilmenite not very much different from that of the aforementioned Fe–Ti–V deposits occurs in augite syenites. In these Al- and Si-undersaturated (agpaitic) magmatic rocks Zr, Ti, Nb, P andREE arestrongly enriched andTi is accommodated in the lattice of rather complex silicates such as neptunite, murmanite, epistolite and rinkite (Ferguson, 1964). Apart from Zr, Nb andREE concentrations, the Ilímaussaq intrusion, Greenland–Denmark, is famousfor its U and Th enrichments with monazite, pyrochlore and eudialyte as the main ore minerals. At Ilímaussaq in Greenland among others eudialyte, steenstrupin and mosandrite are common constituents of the alkaline magmatic rocks. These alkaline Zrenriched melts have been derived by extreme fractionation processes in alkali basaltic or nephelinitic magmas. Two groups of peralkaline magmatic rocks (molar(Na + K)/Al N 1) areknown, both characterized by exceptionally high contents of incompatible elements like Be, Rb,REE, Ti, Ta Nb, Zr and Hf. In the case of peralkaline miaskitic rocks Zr and Hf are incorporated in minerals like zircon, sphene and ilmenite, whereas in agpaitic varieties, these elements form complex Na –(Zr, Ti)–silicates. Various pegmatites are known such as the Lilleelv pegmatite, the hiortdahlite-bearing pegmatite at Tuperssuatsiat Bay and the Narsaq River pegmatite (Robles et al., 2001; Matsubara et al., 2001). Zirconium in eudialyte-rich layers in agpaitic syenites totals 38 Mt grading 1.1% Zr (Laznicka, 2014).

Zircon mineralization was described from the (Sn–As/Zn–Zr)–Tb/ Nb–U–B–Be–P pegmatites Mount Mica, USA by Brown�eld et al. (1993) which is the reference type of kosnarite, [KZr2(PO4)3] and also the Hagendorf –Pleystein Pegmatite Province, where a Zr-phosphatesilicate mineralization came into existence besides zircon, an accessory mineral to many pegmatites (Dill et al., 2008a). Textural observations suggest that both theK –Ba–Zr phosphateand theSc–Zr phosphate(–silicate) found at Trutzhofmühle, a satellite aplite of the Hagendorf – Pleystein Pegmatite Province, are magmatic high-temperature phases. Neither pegmatite is located in a peralkaline intrusion which used to have originated from mantle intrusions. Nevertheless a subcrustal impact on the pegmatite system under consideration during the initial stages of its evolution cannot be ruled out for the phosphatepegmatites in Germany as well as northeastern USA. 4.3.7. Synopsis of REE and Zr pegmatites

REE pegmatites more than Be pegmatites are a manifesto for the in�uence of subcrustal magmatic activity (Fig. 6b). In ensialic orogens, they mark the deep-seated sutures and extended thrustal zones but they are not part of the genuine ensialic pegmatites. In the Alpine Mountain Chain, REE in pegmatites do not occur as reworked entities from adjacent Variscan terrains but used to be a marker of plate boundaries being lined up along the Insubrian Line and its parasite faults. Taking a closer look at the element associations with Nb, Ta, Y, F, Be, Zr, Th, Ti and P in mineral deposits dominated by REE and the typical lithological and geodynamic setting reveals a few magmatic environments where they used to be concentrated throughout the earth's history


(Dill, 2010). It is prevalently the carbonatites (24a E), the alkaline igneous complexes (24b E), and alkalineintrusive rocks (nepheline syenite) (24d E), and to a lesser extent the hydrothermal iron deposits (24c EF). The REE-bearing pegmatites are transitional into intragranitic deposits with Mo–W–U–Be (24a D). The distribution of carbonatites in Africa is illustrated in Fig. 13. On comparison plate mosaic in Fig. 3 and the distribution of Be-bearing gemstones in pegmatites (Fig. 10a) withthese mantle-derived magmatic rocks constituting an ancient triple junction in southern Africaa coincidence of REE pegmatites and magmatic rocks of mantle af �liation cannot be denied (Bosse et al., 1996). Zirconium-bearing pegmatites are closely related to mantle-derived magmatic intrusions. They are also enriched in REE, F and Ti and giving rise not unexpectedly to a series of rare exotic mineral phases. Even in the pegmatites typical of crustal origin such as the Li- and P-bearing pegmatites such subordinate mineral assemblages with Zr and REE can be recognized during the incipient stages of pegmatite formation and considered to be indicative of a subcrustal in�uence on the composition of pegmatites otherwise dominated by elements of crustal origin. 4.4. Uranium–thorium pegmatites and pegmatite–skarns (24 DE + 26 DE)

The two radioactive elements uranium and thorium are ranked very high among those elementswell-known fortheir great varietyof mineral deposits, particularly in magmatic host rocks (Dill, 2010) (Table 5). The most common ore mineral in U deposits is uraninite and its collomorphous variety called pitchblende. Thorianite is the Th-bearing analogue among these U–Th oxides. Uranium and thorium silicates also count among the so-called “ black ore minerals” which predominantly accommodate tretravalent uranium in their lattice (Fig. 15). It is cof �nite [U(SiO4)0.9(OH)0.4], thorogummite [Th(SiO4)0.9(OH)0.4] and thorite [ThSiO4] which make up this group of U –Th minerals. Uranium and thorium titanates such as brannerite, thorutite and davidite are verycomplex chemicalcompounds, accommodating U in its tetravalent state and, in places, also REE in their lattice so that they may also be grouped under the header “ U black ore minerals”. They are also called refractory radioactive minerals because processing of these minerals is often fraught with dif �culties and deposits dominated by these minerals, such as some pegmatites, arenot high up on the list of exploration targets among U companies. Another category of U minerals is called as “ uranium yellow ore” made up of uranyl complexes with hexavalent uranium and a wide variety of hydroxyl groups and anion complexes mainly phosphate-, vanadate-, and arsenate which may show up in uraniferous pegmatites dependent upon the accompanying elements precipitated during the previous stages of the pegmatite formation (Fig. 15b). Thorianite and Th-enriched uraninite are common constituents in pegmatite-hosted and intragranitic U–Th deposits, whereas colloform pitchblende is rare. For a long time the integration of Th into its uranium analogues, hasbeen known tobe closelyrelated tothetemperatureof formation of the uranium black ore minerals (Ramdohr, 1975). While the common U silicate cof �nite is widespread in vein-type and sandstonehosted deposits, its Th-bearing analogues thorutite and thorite prefer syenites and pegmatites genetically related to these magmatic rocks. This chemical variation in U black ore minerals, which has signi�cant implication on the geologicalpositioningof pegmatite-hosted U- andTh deposits becomes more apparent among the U–Ti compounds some of which are almost exclusivelyrestricted to alkalineigneous rocks and their pegmatitic satellite deposits, e.g., davidite La0.7Ce0.2Ca0.1Y 0.75U0.25Ti15Fe3+5O38 (3% U) or dessauite Sr0.75Pb0.25Y 0.7U0.3Ti15Fe3+5O38 (4% U). The uranium contents and the moderate LREE contents both render these black ore minerals not very attractive in search of U- or REE deposits, particularly in view of their refractory character. This can also be applied to some minerals well known from pegmatite-hostedREE deposits,whose U contents are listed below in decreasing order of abundance: xenotime YPO4 (6630 ppm U), zircon ZrSiO 4 (1367 ppm U), monazite (Ce,La,Y,Th)PO4

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(820 ppm U), sphene CaTiSiO5 (196 ppm U), orthite (Ca,Fe) (REE, Al,Fe)3 Si3O12(OH) (180 ppm U) (Fig. 15c, d). 4.4.1. U –Th plutonic pegmatites in the Variscan Metallotect

Although being of very widespread occurrence in the European Variscides, uranium is not an element typical of pegmatites and found more often in vein-type deposits cutting through the basement rocks and locally also extending into the foreland sediments. The Polish part of theEuropean Variscides, beinglocatedat the eastern fringe of theBohemian Massif is particularly enrichedin REE-bearing Th–U pegmatites. In the Karkonosze Granite at Markocice near Bogatynia, in the metamorphic wall rocks of the aforementioned granite, REE–U–Th pegmatites, called metasomatic syenites occur (Mochnacka and Banas, 2000). Mineralogists will be happy about the outstanding mineral assemblage including monazite, thorite, cheralite, grayite, huttonite, ningyoite, voglite, thorogummite accompanied by various sul �des, but engineers who have to seek for techniques to recover the economic elements will not share this enthusiasm. Kucha (1980) reported ThO2 contents of 56.4–69.9 wt.% from the huttonitic monazite-(Ce), which lies between ThSiO4 and CePO4. In the Fore-Sudetic Block rare metalbearingpegmatite veins are known from the Szklaryserpentinitemassif P–U–REE–Be–Nb/Tawhich is also host of uraninite (Pieczka,2000).The age of the Gory Sowie pegmatites was dated to 370 ± 14 Ma ( Van Breemen et al., 1988). This value is slightly lower than that obtained for the uraninite from Szklary (Pieczka, 2000). The emplacement of these Th–U pegmatites is unrelated to the collisional event of the Central European Variscides during the Permo-Carboniferous and re�ects the intensive splitting apart into various terranes in this zone of the Variscides (Quenardel et al., 1988). The Gory Sowie ultrabasic igneous rocks part of a dismembered ophiolite sequence are a suspected allochthonous terrane which was obducted onto the Central Sudetes before the Upper Devonian. It is a good match with the age information given above. The genetic linkage between pegmatite and the geodynamic setting cannot yet precisely been established andone can only suspect of a link between Th-bearing pegmatites and fracturation and/or thrusting. In the Hagendorf-South,Hagendorf-North andKreuzberg pegmatite at Pleystein well-shape octahedral (prevailing crystal morphology) uraninite is found intergrown with columbite-(Fe) (Fig. 15a). Uraninite from the Hagendorf –Pleystein Pegmatite Province, Germany, stands out from the numerous uranium oxides determined in the vein-type U deposits by its particular intergrowth. These crystal aggregates may be quoted as an example of epitactical or law-like overgrowth of octahedral, dodecahedral andcubic uraninite onto Nb–Taoxides(Strunz,1962). Its crystal morphologyandlattice parameters attest to a high-temperature precipitation. It is totally different from thePolish examples describedabove, in terms of mineral chemistry and its accompanying minerals and placed rather central within theCentral EuropeanVariscides. To come to thepoint, thepegmatite system of the Hagendorf –Pleystein Pegmatite Province is, being looked at from a geodynamically angle, part of a collisional event, yet at a distal position and sitting just on top of the root zone of a nappe pile. The Albera pegmatite has been addressed in Section 4.2.2 in the scope of Be pegmatites and mentioned here again for its minor U mineralization related to an anatectic muscovite –biotite leucogranites (Malló et al., 1995). It is a Variscanpegmatite mineralization in a central ancient massif surrounded by a series of rocks submitted to Alpine deformation. Uranium in pegmatites obviously preserved its primary hallmarks adopted during the Variscan orogeny even under subsequent tectono-metamorphic overprinting (Fig. 6b). 4.4.2. U –Th pegmatites in the Proterozoic Metallotect in Africa

Several of the pegmatites on the Isle of Madagascar were also explored for their uranium contents — see also Section 4.3.4 for REE and Section 4.2.3 for Be (Burret, 1988). Burret (1988) recorded uraniferous pegmatites from around Ampangabe, Ambatohasana and Ambatofotsikely with beta�te and pyrochlore-group minerals. It is not one of the common blackore uranium minerals mentioned in the initial

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paragraph of this section but this beta�te averages12–15%ofU3O8. This particular mineral association stands for about 50% of Madagascar's total uranium production. The author grouped the uraniferous pegmatites into (Be)–Nb/Ta–U–Th pegmatites. The predominant micabelongs to the biotite s.s.s. in this group of U –Th pegmatites. The second type may be described following the CMS classi�cation as Be–U–Th pegmatite, where muscovite prevails over biotite among the mica minerals present in the pegmatite. Such rather primitive biotite pegmatites are also known from elsewhere in the world in crystalline rocks with sillimanite, cordierite andbiotite, e.g., around the Hagendorf –Pleystein Pegmatite Province. Next to these biotite pegmatites two lithologies, very much different from each other and strongly contrasting with these biotite pegmatitescan be found.It is a series of gabbroic, dioritic to granodioritic rocks mostly occurring in dikes and skarn-type mineral assemblages with mainly grossularite, diopside–hedenbergite, vesuvianite, zoisite and scheelite. In subordinate amount wollastonite has been proven. Apart from the high-temperature alteration indicated by wollastonite, the ma�c to intermediate intrusive rocks attest to a deep subcrustal source. Pezzotta gave a short note on what he called alkaline skarns and urano-thorianite mineralization in Southern Madagascar (Pezzotta and Simmons, 2001). Presumably, the mineralization took place along shear zones intersecting granulite-facies crystalline basement to thesouth of theRanotsara–Bongolava ShearZone, Madagascar.The lithological setting shows a contact of undeformed alkaline magmatic intrusions in association with carbonate-bearing and pyroxenitic metamorphic rocks. The “ alkaline skarns” frequently take on a pegmatitic grain size accompanied by an exceptional concentration of minerals like phlogopite, diopside, scapolite, titanite, andradite, thorianite, zircon, apatite, spinel, and many others, including locally corundum varieties, hibonite, sapphirine, kornerupine, and grandidierite. Although the exotic enrichment of U–Th is far from being convincingly explained as to its origin, hypotheses such as a pegmatite-related pneumatolitic melting of marbles have been put forward. These mineral assemblages formed during metamorphism at temperatures exceeding 850 °C and a pressure of 7 to 8 kbar (about 20km deep inthe crust), duringthe latest stages of the Pan-African uplift and cooling down about 490 Ma ago (Rakotondrazafy et al., 1997). The Ntebenipegmatite,in Mashonaland, EastZimbabweis a (Zr)–U– Th pegmatite with thorite, uranothorite and zircon (Gallagher, 1967). The most prominent pegmatitic to intragranitic U deposit in Africa lies in Namibia, in the Rössing Hills near Swakopmund ( Fig. 16). The ore deposit is located within the h igh-grade metamorphic rocks of the DamaraOrogen.Masberget al.(1992) attributedthe regionalmetamorphism in the central Damara Orogen to the granulite facies of lowpressure type. The resultant metamorphic rocks wereintruded by granites. The low-grade-large-tonnage U deposit is characterized by a widely concordant layering of U-bearing pegmatites, aplites and pegmatitic granites, the latter attributed to the alaskitic clan by Berning (1986), Nex and Kinnaird (1995), Basson and Greenway (2004) and Kinnaird and Nex (2007). At the contact of the alaskite to its wall rocks a contact-metamorphic aureole may be observed which is indicative of a temperature disequilibrium and the presence of a melt phase that has been intruded into the metamorphic basement of the Damara Province. This crustal section of south-western Africa was studied in great detail by Tankard et al. (1982), who took this crustal section as a reference for an ensialic mobile fold, which is characterized by nappe stacking a setting very much different from what we know of the classical Wilson Cycle Concept. Basedupon theminerals known from the deposit, it may be classi�ed as a (F–P–As–Mo–W)–Th–REE–U pegmatite. Despite its abundance in REE minerals, uraninite makes up 50% of the minerals from which U is recovered. Another 45% derive from yellow U ore minerals and a minor amount from beta �te, which is predominantly enriched in sheeted leucogranites. The uraniferous pegmatitic leucogranites are held to be bound to A-type magmatism. The uraniferous pyrochlore is closely linked to basic rocks magmatic in

origin, such as Nb- and Ti-bearing amphibolites of the Rössing Formation or metacarbonates. Another ore-controlling factor may be envisaged to have exerted by the structural setting in that antiforms with amphibolites and marbles to pond the rising �uids from escape. Uraniferous beta�te is 500 Ma in age and the mineral association another example for a Pan-African late-kinematic emplacement of pegmatites. The question still waits an answer whether the melt is totally derived from a subcrustal source or whether the pegmatitic granites have scavenged elements from sedimentary and magmatic crustal rocks abundant in U, Th and REE (protore, or low-metal preconcentration). As shown for some pegmatites from Central Europe by Dill (2015) the emplacement is neither a mono-phase process nor have they been fed by one source only. The chemical composition is simply a mirror image to what extent crustal andsubcrustal processes wereaccountable for the pegmatitization. Metamorphosed alaskitic rockselsewhere, such as at Charlebois–North Athabasca basin, Canada and Johan Beetz in the Greenville province of Quebec, Canada undercut grade and tonnage of Rössing, Namibia and today held as uneconomic. 4.4.3. U –Th pegmatites in South and North America

A series of A-type granites were intruded during the Carboniferous in NW Argentina in the pro-Andean foreland. Although being quite rich in Th and some of them also in REE no enrichment to economic grade took place (Dahlquist et al., 2010). Uraniferous pegmatites are found also in the Comechingones Pegmatitic �eld (CPF) is located in the southeastern Pampean Pegmatitic Province, in the northwestern Sierra de Comechingones, Córdoba province, NW Argentina (Galliski, 1994a,b, 1999) It is composed of several Be–Nb–Ta–P–U-rich pegmatites. According to Demartis (2010) the pegmatites from the southern CPF developed i n a P–T regime of 500 MPa and 600–700°C. In Brazil, Th-bearing pegmatites are known in the States of Bahia, Minas Gerais and Goias but the top scorer, albeit of subcrustal origin, is a non-pegmatitic deposits. The alkaline intrusion at Araxá has Th associated with pyrochlore. A classical example cited as a pegmatite-hosted uranium depositlies in the Bancroft area in Ontario, Canada (Goad, 1990). Uraninite and other uranium–thorium minerals were accumulated in sheared simple granitic pegmatites, pegmatitic granites, and syenitic pegmatite that are conformably intercalated with metagabbro, amphibolite,amphibole gneiss, and biotite gneiss. They were metamorphosed to the amphibolite grade of regional metamorphism. Metasomaticprocesses and deformation are post-metamorphic. The grade of this uraniferous pegmatite stands at 800 ppm U. A similar site with uraniferous pegmatites is at Campbell Island, Canada. 4.4.4. Synopsis of U –Th pegmatites

Rare metal pegmatites such as Greenbushes, Australia, (6–20ppmU and3–25ppmTh, IAEA,2009) averagehighercontents of radioactiveelements than granites, but do not qualify generally as uranium or thorium deposits. Uranium and thorium in pegmatites is rather seldom enriched to economic grade and the number of U –Th-bearing pegmatites trail far behind the number of Sn-, Li-, Nb/Ta- and Be-bearing pegmatites mined for the aforementioned commodities be it for the recovery of the element itself or for gemstones accommodating Li or Be in their structures. There is a close link between A-type or mantlederived alkaline magmatic rocks like Palabora, South Africa, Ilimaussaq, Greenland and the intraintrusive-pegmatitic rocks at Rössing.The more Th and REE dominate the element composition of uraniferous pegmatites the more evident it becomes that a strong interference with subcrustal material has taken place. Thorium and REE-poor or -free element associations are less likely to have a direct connection with a subcrustal source and used to be uneconomic as to the elements in question. Basic rocks of the sedimentary and magmatic realms or their metamorphic analogues, when being involved in the concentration of these elements have not only a physical effect of ponding rising � uids but also may be involved chemically. They behave as marker lithologies


for that involvement or they stand out as a skarn deposits related in time and space with the pegmatites. With respect to the derivation of themeltproducing a pegmatite andas to theinvolvement of basic countryrocksinthemake-upofthe �nalcomposition of a pegmatites,a closer look at the petrological and tectonic criteria offered by Rogers et al. (1978) may shed some light on these enigmatic issues. Discrimination based upon the Th/Uratios and initial 87Sr/86Sr ratios enable us to split up thegroup of pegmatitic deposits. Th/U ratios below 1 combined with high initial 87Sr/86Sr ratios suggest anatectic and migmatitic processes to have predominated in the formation of the uraniferous pegmatites such as at Rössing, Namibia, and Bancroft, Canada (Table 5). Remobilization of crustal material with a uraniumlow-metal concentration can be taken accountable as a source for these uraniferous pegmatites while normal alaskites elsewhere are infertile. Metasedimentary terrains with abundant pelites h ave uranium contents well above Clarke values, and therefore can account for a pegmatitic uranium concentration or an intrusive-related U deposit. Th/U ratios greater than 1 along with low initial 87Sr/86Sr ratios are common to sodium-enriched post-tectonic intrusive rocks such as albite–riebeckite granites which have derived directly from a lower or subcrustal level (Table 5). Between syngenetic disseminations of uranium and thorium minerals found in alkaline igneous rocks such as Ilimaussaq, Greenland, Pocos de Caldas, Brazil, and carbonatites, like Oka, Canada and Araxa, Brazil, on one side and the pegmatitic and intragranitic analogues at Rössing on the other, no sharp boundaries exist when these rocks are viewed with respect to their geodynamic setting and their processes of formation. Processes like albitization and contact-metasomatic processes in metacarbonates and ultrabasic igneous rocks, such as pyroxenite skarn, e.g., Madagascar,Bancroft-Canadaand Rössing put the world in a different light (Satterly, 1957; Berning et al., 1976 ). A comparison between the U –REE–Nb–Zr deposit at Bokan Mountain in the Jurassic Bokan Mountain peralkaline ring-dike intrusive complex and the Rössing pegmatite is carried out to highlight the common items anddifferences as a function of geodynamic positioning.The U–Th mineralization is associated with intense albitization and chloritization (calcite, �uorite, quartz, sul�des, tourmaline, hematite). Uranothorite and uraninite are the main ore minerals (Philpotts et al., 1998; Dostal et al., 2011). For equivalent features at Rössing, Namibia, see Section 4.4.2. At the end of this discussion, another issue is addressed in this study upon pegmatites, to what extent these rocks play a role as some kind of a subeconomic protore for different types of economic uranium deposits. Annesley et al. (2010) investigated mineralized granitic pegmatites/leucogranites which occur within the contact zone between Wollaston Group metasediments and underlying Achaean orthogneisses in the Athabascan basin, Canada. Apart from the typical rock-forming minerals of pegmatites they also contain subordinate amounts of apatite, monazite, allanite, U-rich zircon uraninite– uranothorite–thorite, and ilmenite. Age dating yielded 1770 ± 90 Ma for the pegmatite and gave some younger age clusters. The younger age data point to a post-Athabascan alteration of these granitic pegmatites during which these felsic rocks h ave provided U for the renowned unconformity-type uranium mineralization in the region. 4.5. Fluorine-boron pegmatites and pegmatite–skarns (32 DE + 30 D)

It is a classical theory that wasput forward by Daubrée(1841) toexplain the precipitation of cassiterite in greisen-type Sn deposits or granitic pegmatites –SnF4 þ 2H2 O≫SnO2 þ 4HF –SiF4 þ 2H2 O≫SiO2 þ 4HF :

As an alternative boroncan take theplace of �uorine in the magmatic environment.

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Despite this prominent role of boron and � uorine in the granitoids, conceded by Daubrée (1841) and his contemporaries, these felsic intrusive rocks are not the � rst choice in search of boron as a raw material. There is a wide spectrum of Na borates (playa lakes in the USA, Turkey, Argentina), Na–Ca borates (playa lakes in Chile, Peru, USA, Turkey, Argentine), Ca borates (USA, Turkey, Russia) and Mg borates (China, Turkey, Permian salt deposits in Europe) which are con �ned to boron (borate) deposits sensu stricto in (volcano) sedimentary environments where the elemental boron is used to be recovered from (Helvaci and Alonso, 2000). In addition to these borates, a group of boron silicates exists whose members resist supergene and hypogene alteration and found frequently in granites where they got continuously enriched during the evolution of granitic magmas and �nally concentrated within the apical parts of peraluminous granites, greisens and granitic pegmatites (Trumbull and Chaussidon, 1999; Thomas et al., 2003 ). The hardness combined with a wide range of hues and shades render some members of these boron silicates, particularly of the tourmaline s.s.s. very attractive as gemstones (rubellite: red to pink, indigolite: green, Paraiba tourmaline/elbaite: blue, watermelon tourmaline: zoned tourmaline, dravite: brown, schorl: black, achroite: colorless). A generic formula for the tourmaline s.s.s. is X1 Y 3 Al6 B3 Si 6 (OH)4 with X = Na and/or Caand Y = Mg, Li, Al, and/or Fe2+ (Fig. 17a,b, c, d, e). For more information on the crystallographic part and classi �cation of tourmalines the reader is referred to Novák and Kadlec (2010) and Novák et al. (2004, 2011). Some boron-bearing minerals are looked for mainly by small-scale miners in pegmatites, granitic pegmatites, and contact-metasomatic rocks related to pegmatitization, such as skarns and presented in Table 6. What has been discussed above as to the economic geology of boron can also be applied sensu lato to � uorine. The element � uorine is concentrated by fractional crystallization during the latest stages of granite emplacement and similar to its associate boron enriched in the apical part of the most strongly differentiated so-called “Tin Granites ”. It is rarely the mineral � uorite and normally the mineral topaz which shows up in this environment. Apart from this alumosilicate, �uorine used to be accommodated also in the micagroup sheet silicates and in apatite where it substitutes for the hydroxyl group and as far as the phosphate is concerned also for chlorine and the carbonate. Fluorite is the only F-bearing mineral currently exploited on a commercial basis from a wide-range of structurerelated F deposits and sedimentary F deposits, whereas � uorine as a by-product of mining phosphorites is only a reserve to be used by future generations (Dill, 2010). But there are also some magmatic deposits, such a volcanic-hosted F –U–Mo deposits, granite-related Be–Nb–Ta–�uorite deposits, in places with skarn deposits where �uorine can be won. Granites and granitic pegmatites may give rise to topaz in miaroles which achieve gemstone quality similar to their analogues on the boron part. What renders � uorine strikingly different from boron is the close link of � uorite deposits to U –REE carbonatites and alkaline intrusive rocks as shown by different sites across the globe: Amba-Dongar in Gu jarat State, India, Okurusu, Namibia Mountain Pass, USA, Speewah, Australia, and Rock Canyon Creek, Canada. Of particular interest for mineralogists, the metasomatic cryolite deposits in Greenland have to be referred to in this place for its close relationship to metasomatic Atype pegmatites.These mineralassemblages are known fromGreenland andthe northern rim of theBrazilian Shield, yetnot at recoverable grade (anymore). In Ivigtut, Greenland, apart from cryolite, base metal sul�des were recorded in remarkable concentrations from the rime of the pegmatite (Bailey, 1980; Pauly, 1992; Petersen and Secher , 1993). It has to be noted that this high-temperature sul�de mineral assemblage with Fe-enriched sphalerite can also be found elsewhere in calcalkaline phosphate pegmatites, such as Hagendorf-South and Pleystein, Germany.

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Boron and �uorine in pegmatites might take on the role as a marker element to discriminate between different geodynamical settings. Can �uorine and boron also be used to constrain crustal and subcrustal derivations of pegmatites? 4.5.1. F –B pegmatites in the Variscan metallotect

Fluorine and boron-bearing pegmatites are con�ned in the Central European Variscides to the Saxo-Thuringian Zone, or in geomorphological terms, the Fichtelgebirge–Erzgebirge Anticline which straddles the German–Czech border. From the geodynamic point of view this region is most proximal to the frontal thrust or sub �uence zone where continent–continent collision conduced to a thickening of the crust and which later was exhumed and intruded by a huge volume of granitoids. Weber (1978)proposed a sub�uence model which may be regarded as a plate tectonic modelincludingthe special features of an ensialic orogen— see also Table 3 and Fig. 9f. The superimposed uplift and tectonic shortening leads to horizontal overthrusts and, in places, a stacked pile of nappes. Sub�uence in theRhenohercynian zone is interpreted in connection with the movement of larger lithospheric plates which transgressed the limits of the Rhenohercynian zone and the Subvariscan Foredeep. This Central European region has already been treated when discussing the Sn–W deposits of greisen- and pegmatite-types (stockscheider) — Section 4.1.1. These rare metal deposits may be classi�ed as granitic pegmatites (miarolitic) and to a lesser extent as pegmatite–aplites and pegmatoids (Dill, 2015). Five different groups can be singled out according to the CMS classi�cations along the Fichtelgebirge–Erzgebirge Anticline: (1) B-, (2) Be–B-, (3) Be–B–F–Li–Sn-, (4) Be– F–B–Li–U- and (5) Sn–F–P–As (granite) pegmatites. In the Erzgebirge a trend with increasing boron concentration in the granitic and pegmatitic melts from E to W canbe recognized.This chemical trend is mirrored also in the secondary �uid inclusions of quartz from the granites. Heading further south within the Bohemian Massif, into the Moldanubian Zone of the Central European Variscides, perpendicular to the strike of the geodynamic units, the boron content strongly increases at the expense of � uorine whose minerals � uorite and topaz gradually disappear from the mineral assemblages of the rare element pegmatites (Fig. 2.1a). Tracing the Saxo-Thuringian zone parallel to the strike of the Variscides towards the West will get us through the Cornubian Ore Field, Great Britain, where high-F topaz-bearing greisenized leucogranites exist, into the Portuguese part of the Variscides on the Iberian Peninsula (Fig. 2a). There, � uorine is incorporated into micaceous sheet silicates, into topaz as well as some phosphates in a wide range of aplitic and pegmatitic sills of the Guarda –Belmonte area, and at Gonçalo and Segura, Portugal, in pegmatitic rocks which are emplaced in two-mica-granites and muscovite granites intruded into Cambrian schist-metagraywackes (Neiva et al., 2001; Neiva and Ramos,2010). Tourmaline is present as accessory mineral in the aforementioned pegmatites and aplites and moreover at Vidago, Portugal, in aplite veins intersecting Silurian schists and metagraywackes. At Paredes da Beira the pegmatite is located within a two-mica-granite and muscovite granite intruded into Cambrian schist-metagraywackes similar to the aforementioned examples (Neiva et al., 2001). Topaz was also recorded from the Alvarrões Pegmatite, Central Portugal, and the pegmatites of the Beauvoir Granite, France (Cheillelz et al., 1992; Ramos et al., 1995; Charoy et al., 2003). Shifting our view to the inner zone of the West-European Variscides reveals for some pegmatites a striking difference when compared with the outer zone. The Cap de Creus pegmatite region, Spain, is located at the eastern end of the Pyrenees and belongs to the deepest zone of the Variscides in the region (Carreras et al., 1975; Melgarejo et al., 1990; Alfonso and Melgarejo, 2000). Its country rocks can be attributed to three different facies zones with regard to the regional metamorphism, arranged in order of increasing metamorphic grade: (1) greenschist facies, (2) amphibolite facies, and (3) cordierite –sillimanite facies. Metamorphic rocks of the highest metamorphic grade are intruded by granodiorites

and gave host to tabular pegmatites. Tourmaline s.s.s. encompasses dravite, schorl, in parts present as rubellite variety, while � uorine is only present as �uorite. In the pegmatite deposits of the Sierra Morena around Córdoba, in Andalusia, Spain, � uorite is the F-bearing mineral (Garrote et al., 1980; Ortega Huertas et al., 1982 ). By and large, the B/F ratio increases from the external zone towards the internal parts of the ensialic orogen, opposite to the thrustal movement. The �uorine contents in the pegmatites go down to almost nil in what might be considered as the root zone of the nappes. Judging by the mineral assemblages observed in the Austrian Alps and Western Carpathian, boron plays only a moderate role and �uorine can be neglected in the Older Variscan Massifs that were incorporated into the modern Alpine fold belt. 4.5.2. F –B pegmatites in the Proterozoic metallotect in Africa and South America

Boron is quite common in many pegmatites of the Precambrian metallotects on the southern hemisphere, whereas � uorine is rather scarcely distributed in what is known as Gondwana ( Tables 7a, 7b, Fig. 18a, b). 4.5.2.1. Fluorine in pegmatites. Only a few examples of F-enriched peg-

matites shall be discussed in this section. The early Proterozoic Volta Grande pegmatite deposit in Minas Gerais, Brazil, operated for Sn and Ta also containsF-bearingmineralssuch as �uorite,micaceous minerals. Furthermore the deposit is the type locality of a rather complex Fbearing Nb–Ta oxide of the microlite group, � uorcalciomicrolite [(Ca, Na,□)2Ta2O6F] (Andrade et al., 2013). In the zoned (U–B–F–Be)–Ta/ Nb–Sn–Li pegmatite (spodumene–holmquistite –Li mica) high Rb contents correlate with high F contents and can be interpreted in terms of a metasomatic process (Quéméneur and Lagache, 1999). The (Be–F– U–Bi–Pb–Zn–Cu–B–Sn)–Li–Nb/Ta–P pegmatites from the Borborema Province, northeastern Brazil, also contain a moderate �uorite mineralization (Beurlen, 1995; Beurlen et al., 2001, 2009, 2014). The age of formation is Early Paleozoic, based upon the U/Pbdata published by Araújo et al.(2005) and Baumgartner et al.(2006) whose data plot in therange 523 ± 2.5 Ma to 494 ± 15 Ma. It has to be noted, that both provinces lack topaz. The Li–F–W–Sn pegmatites tabular and vein-type deposits described in Section 4.1.3 from Bom Futuro, Brazil, are in stark contrast to these types. These Li–F–W–Sn pegmatites are signi�cantly older than the Borborema pegmatites but younger than the Volta Grande pegmatite. They contain topaz in a great variety of igneous host rocks and they are boundto anorogenic granites.Students of the �uorite-bearing pegmatites mentioned above are hard pressed to �nd a so-called “parental granite”, a problem which manyresearchers are facedwith dealingwithpegmatites. Concluding from the studies along the western edge of the Bohemian Massif, Germany (Dill,2015), thetwo main representative of �uorine in pegmatites re�ect two different phases in the evolution of these rocks. Fluorite and to a lesser extent carlhintzeite [Ca 2AlF7·H2O] and pachnolite[NaCaAlF 6·H2O] are secondary products, derived from the decomposition of F-bearing phosphates, e.g. manganiferous apatite(F) and in some cases mica, e.g.,lepidolite. Topaz, however, is a primary mineral that predominates in most pegmatites derived from A-type granites with Sn. In some particular cases it can be substituted for by cryolite [Na3AlF6]. The second site which also brings topaz into existence is located within the shallow Variscan Granites in Central Europe as pegmatites were emplaced in the frontal parts of the zone of thrustal movements (Fig. 9f). There are numerous topaz occurrences in remote areas in Pakistan, Afghanistan and Brazil. Often the minerals are well described and treated according to the up-to-date gemological methods but the lithological, structural, and chronological setting is often very poorly known so that we might expect an estimated number of unreported cases which might force us to change oneor theotherfacetsof our picture on thepositioning of topaz-bearing pegmatites. Topaz mineralization at Shingus, Haramosh


and Stak Nala, east of Gilgit in the Haramosh Massif within the IndoPakistan plate, and furtherE intheDusso NyitBrukMine intheKarakorum Batholith within the Asian plate, Pakistan, may be some of the areas still waiting for some more detailed �eld work (Menzies, 1995). A different approach may be taken to interpret the concentration of topaz in pegmatites and harness the numerous gemological data available on this gemstone to shed some light on the geological setting of pegmatites. The Groote Spitzkopje biotite granite intruded during the waning stages of the Damara orogeny about 530 Ma ago (Pan-African) (Frindt, 2000). The pegmatite related to an A-type granite provided specimens of world-class topaz. Gemological investigations of the topaz by Cairncross et al. (1998) revealed refractive index values that are somewhat lower, and speci�c gravity values that are slightly higher, than those of topaz from similar deposits. The data obtained are more appropriate to topaz from rhyolitic deposits than from pegmatites, and apparently correspond to a higher �uorine content. This is not anything spectacular if you take a closer look at thecomplex suite of A-type lithologies at Bom Futuru across the Atlantic Ocean in Brazil, where anorogenic topaz granite porphyry and topaz rhyolite occur side-byside. It attests to a rather shallow environment and opens up a connection to rocks discussed later in this review — see Section 6. The latter section using the gemologicaldata of topaz refers particularly to a great number of topaz-bearing pegmatites in Brazil, Madagascar, Namibia and Pakistan where the main sources of transparent colorless and blue topaz are located. The imperial topaz continued to originate from theOuro Preto regionof Minas Geraisin Brazil. Some of themost important topaz and �uorite occurrences in pegmatites operated for highquality topaz and suitable for such an approach were extracted from Dill and Weber (2013), a gemological appendix to the “Chessboard Classi�cation scheme of Mineral Deposits” and listed in Table 7a. 4.5.2.2. Boron in pegmatites. In Section 4.5.2.1 our view was directed to topaz as a gemstoneused on a commercial basis andas a potential gemological marker for a lithological and geodynamic classi �cation of pegmatite deposits worldwide or to be more speci �c in “Terrae incognitae” in South America, Asia and Africa. This applies all the more so formost of thecoloredvarieties of tourmalineand itsgemological associates listed in Table 6, the gemmy material of which is found only outside the Variscides (Section 4.5.1) mainly on the southern hemisphere andEastAsia (Table 7b, Fig. 19a, b). In Brazil,tourmaline pegmatites (schorl) or B pegmatites are also quarried as ornamental stones for its peculiar structures which are in parts pegmatite-derived but also caused by the integration of metamorphic xenoliths into the felsic melt (Fig. 19b). In the tourmaline pegmatite at Taquaral, Brazil, a pegmatite belonging to the Brasiliano Orogeny (ca. 500 Ma) fragments of biotite –cordierite gneiss have been incorporated from the country rocks and now � oat as slices within the felsic melt (Fig. 19b). There seems tobe little doubt that theelevated boroncontentof thepegmatite and the dissemination of schorl can be traced back to the marine metasediments in the endo- and exocontact of the B pegmatite. As a reference site for these B pegmatites in South America, the boron-enriched Coronel Murta Pegmatite Field is described in more detail. The ore �eld belongs to the Ara uai District, Brazil. Numerous small pegmatites occur in this district together with the G 4 granites of the Itaporé Suite (Pedrosa-Soares et al., 1990, 2001; Pedrosa-Soares and Oliveira, 1997; Castañeda et al., 2001 ). The batholith consists of biotite granites, two-mica granite, garnet-muscovite granites and pegmatoid granites. Thebiotite granite forms the root zone of the batholith,followed towards the top by two-mica granites and garnet–muscovite pegmatites. In places, a pegmatitic cupola evolved in the apical part of the granite, similar to what has been described from the Erzgebirge as “stockscheider” — see Section 4.1.1. The pegmatites are not con�ned to the uppermost part of the granitic batholith but also observed as tabular pegmatites within the quartz–mica schists and in the metagraywackes of the Late Neoproterozoic Salinas Formation and in the quartzite of the Middle Neoproterozoic Macaúbas Group. The pegmatitic rocks in the

479

various country rocks differ from each otheras to their structural outward appearance. In the Middle Neoproterozoic metapsammitic rocks a series of pegmatitic dikes �lled the fractures opened up in the hard quartzites and run at high angle to the schistosity, whereas in the Late Neoproterozoic, tabular pegmatites evolved along the cleavage planes of the metamorphic rocks. The authors assumed that pegmatites were emplaced at a crustal level between 12 and 15 km depth. Tourmaline of schorl- and elbaite-typeco-existswithberyl, herderite bismuthinite, apatite, aquamarine, spodumene, lepidolite, amblygonite–montebrasite, and some other phosphates. From thecommercial pointof view, thetopparts contain the pockets and fractures mineralized with tourmaline of jewelers' quality, with only one pegmatite producing 50 t of bi-color pinkgreen elbaite, while towards the depth pegmatite became on important site for the extraction of feldspar (Fig. 19c, d). There are still some open questions such as those: Is the structure of the pegmatite bodies an issue related to therock-mechanicsor related totheage of emplacement? Theorebodies illustratedby Pedrosa-Soares et al.(2001) are lensoid bodies intercalated into the metamorphic country rocks at low angle and balloon-shaped pegmatitic bodies arranged as high-angle-dipping pegmatites (Fig. 4n). According to the cartoon published by the authors, the pegmatites evolved after the consolidation of the granitic host rocks. Putting together the mineralogical data and interpreting the structural features, enable us to categorize the tourmaline-enriched pegmatites as Bi – Li–P–Be–B pegmatites tabular and stock-like. The �rst one may be attributed to the hinge zone and the second one to the limb zones of syn- and antiforms in the metasedimentary series. Elbaite-type tourmalines are among the most looked-for tourmalines, particular their Cu-bearing variety, which has been discovered for the �rst time in Brazil, and fetches a high price even if similar tourmalines have recently been discovered elsewhere in Mozambique (Laurs et al., 2008). This extraordinary tourmaline called Paraiba Tourmaline was discovered near Salgadinho, Brazil, in pegmatites which were intruded into Proterozoic muscovite–quartzites. It is an atypical tourmaline of bluish-green to medium blue-green color. These most precious tourmalines of its kind contain bivalent copper as chromophore and is as such responsible for the attractive blue color (Karfunkel and Wagner, 1996) (Fig. 19c). In the Jonas Mine (João Pinto mine) a (Be –P–Sn–REE)–Nb/Ta–Li–B (Li silicate) pegmatite is worked for rubellite (Wilson, 2012). Tourmalines are taken from pegmatites that are intrusive into schistose or granitoid rocks. Other sites producing high-quality tourmaline are known from, e.g., Nepal (Hyakule, Phakuwa), Russia (Mursinska Mts. in the Ural Region), Kenya (Voi-Taveta) and Zambia (Chipata). The pegmatite-forming processes responsible for the formation of boron pegmatites were investigated in detail by Zagorsky and Peretyazhko (2008)and by Thomas et al. (2012), targeting the Malkhan in Transbaikalia, Russia. The pegmatite-forming processes started at magmatic temperatures around 720 °C. The primary melts or supercritical �uids were very water- and boron-rich (maximum values of about 10% (g/g) B2O3) and over the temperature interval from 720 to 600 °C formed a pseudobinary solvus, indicated by the coexistence of two types of primary melt inclusions (type-A and type-B) representing a pair of conjugate melts. Due to the high water and boron concentration the pegmatite-forming melts are metastable and can be characterized either as genuine melts or silicate-rich � uids. During the evolution of the pegmatites the gel- or gel-like state has left traces in form of real gel inclusions in some minerals in the Malkhan pegmatite yet only in a late, �uid dominated stage (Thomas et al., 2012). Many tourmaline mineralizations re�ect a rather complex history (Simonet, 2000). Bicolor tourmaline of gem quality from the Yellow Mine in the Mangare area (southern Kenya) occurs in a pegmatite which has undergone several stages of deformation, metasomatism and metamorphism; they resulted from the interaction of pegmatites with different lithologies such as ultrabasic rocks or marbles. The above account on the genesis of B pegmatites in Brazil, may in some cases be surpassed by the complicated history which the gem-

480


tourmaline-bearingpegmatites Korgal,Nilaw and Mawi, in the Nuristan Region, Afghanistan, went through (Fuchs et al., 1974). It is a series of complex migmatites, mica schists, quartzites and marbles with a suite of granitic intrusions and, to a larger extent, by diorites and gabbros. The pegmatitic rocks, a swarm of layers, strongly folded within the diorites and gabbros are rather called pegmatoids, whose way of emplacement is still today not well understood. Fuchs et al. (1974) claimed that Paleozoic sedimentary series on topof migmatites, were metamorphosed and intruded by a series gabbros, diorites, and biotite–amphibole granites provoking a remobilization of the migmatites. The age of the basic to intermediate intrusions is supposed to be Early Cretaceous and that of the granites of Oligocene age followed by the emplacement of the pegmatitic rocks — see also the European branch of theAlpine-Himalayan Mountain Belt in Section 4.3.2. The foldedpegmatitic rocks are Cs–Sn–Nb/Ta–Li–Be–B pegmatoids (kunzite-lepidolite). A geological-minded account on the Kenyan deposits was given by Pohl and Horkel (1980) in which both authors highlighted the importance of the Pan-African Orogeny for the emplacement of tourmalinebearing pegmatites. Tourmaline also occurs in association with desilici �ed plumasitic pegmatites renowned for their ruby occurrences — see also Section 4.13. Green tourmaline formed in that area in pegmatites and pegmatoid segregations. Danburite and dumortieriteof gem qualityare observedin pegmatites together with tourmaline and spodumene, e.g., in Madagascar. The host rocks are metapsammopelitic rocks and metacarbonates. Jeremejevite is a rare constituent of the late stage hydrothermalalteration of pegmatites. The B-bearing pegmatites in the Antananarivo Province, Madagascar, are classi�ed as (F–REE–Bi–Li)Nb/Ta–Be–B pegmatites. 4.5.3. Synopsis of F –B pegmatites

To draw a clear picture of the distribution of F and B in rare element pegmatites with respect to the geodynamic settingis not easy andrather heterogeneous, particularly as far as �uorine is concerned (Fig. 6b). Both elements tendto be concentratedin Sn–W pegmatites, emplaced at shallow depth in the frontal parts of the collision zone or in other words away from the root of the thrust zones in an ensialic orogen. Boron is an element typical of the crust and, hence, its contents in the pegmatitic rocks increase towards the core zone of the metallotects at the expense of �uorine. The latter has another source, the mantle, as demonstrated by the close link of �uorine to A-type granitoids and their pegmatites. This picture less clear as that of uranium and thorium in pegmatites is due to the different characters. Fluorine, a gas, is without any doubt a member of the group of non-metals, boron however has to be attributed to the metalloids with non-metal-like and metal-like properties, the latter of which come into full effect when reacting with �uorine. Palmer and Slack (1989) raised expectation to clarify some of these open questions using the isotope composition of boron in tourmalines. They mentioned as potential controls over the boron isotopic composition of tourmaline the following factors: (1) composition of the boron source, (2) regional metamorphism, (3) water/rock ratios, (4) seawater entrainment, (5) temperature of formation, and (6) secular variation in seawater. Trumbull and Chaussidon (1999) demostratedthatin pegmatite–aplite dikes (− 12.7 to 21.6 ‰) the boron ratio is higher than in hydrothermal tourmalines (− 18.0 to − 23.0‰) and interpreted their �ndings as a result of � uid fractionation. Hervig et al. (2002) published B isotope data obtained from experimental studies of melt/�uid fractionation of − 5‰ at 650 °C to − 14‰ at 350 °C.Apart from this strongdependance of the boron isotope ratios from �uid fractionation there are also some values that can be used as some kind of provenance marker. Values published by Marschall and Ludwig (2006) within a range of − 11.3 ± 5.4 ‰, corresponding to what is known from S-type granites that have originated by anatectic process from metasedimentary rocks. Martin and De Vito (2005) mentioned that the isotopes of boron in tourmaline and danburite reveal clues about the unusual geochemical environment, taking as an example a hybrid pegmatite system from Madagascar. At the end of listing

these isotope results and their interpretation, which is by no means complete, the conclusion may be drawn that some indications pointing to a crustal source of boron exist but the wealthof factors on the control of boron isotope ratios renders this highly-sophisticated method of isotope studies less ef �cient than a classical chemical review conducted as a function of the geological setting. The otherwise well-fractionated granites from the Fichtelgebirge, Germany, fail to reveal any trend and no gradual increase of boron can be claimed for the G 1, G 2,G 3 and G 4 granitesthat are arrangedin decreasing age of formation (Richter and Stettner, 1979). The boron contents known from the NE Bavarian pegmatitic and aplitic rocks lie with 672 ppm B well above the average reported for the most strongly differentiated granite G 4, yielding 17 ± 8 ppm B. Thus, a transfer of boron from one of the granites even into the most proximal granitic pegmatites or those pegmatites bodies at a more distal position is unlikely. As the average grades of pegmatitic and aplitic rocks are precisely be monitored andcheckedagainst themean values of thegneissic country rocks the paragneisses seem to be closer to the source of boron than thefelsic magmatic rocks (Dill, 2015). The boron contents in the gneissic country rocks under consideration in the Hagendorf –Pleystein Pegmatite Province show strongly positive correlation with aluminum, potassium and phosphorus (R B–Al = 0.78, R B–K = 0.80, R B–P = 0.89), which stresses a close genetic link between boron and the marine phosphate-bearing (meta)pelites. The data well accord with the �ndings published in the classical paper by Harder (1970), that clays contain more boron than sands or limestones and micaceous phyllosilicates contain more boron than smectite-enriched sediments. Boron is supposed to be directly incorporated into these felsic mobilizates, by-passing the granites, whose boron trend is not corroborating the granites' role as an intermediate repository for thiselement. Tourmaline is ubiquitous in many pegmatitic rocks, be it a metapegmatite or a true pegmatite, even if there is no granite nearby. 4.6. Phosphate pegmatites and pegmatite –skarns (38 D)

Phosphorus signi�cantly differs from the aforementioned elements boron and �uorine found at abnormally high contents in rare metal pegmatites. Contributing with approx. 1010 ppm P to the chemical composition of the lithosphere, phosphorus is among the top-ten elements in the earth's crust, although at the bottom of this “ league”. In nature, phosphorus is bound exclusively to oxygen, forming a large and ever-increasing group of phosphate minerals mainly in the pegmatites and thereby rendering them the topscorer among the host rocks contributing to new minerals. The Brazilian pegmatites are abundant in primary and secondary phosphates, mainly concentrated in or proximal to the core zone of the phosphate pegmatites (Fig. 20a,b,c,d,e). The Hagendorf –Pleystein pegmatites in NE Bavaria are a treasure box for enthusiasts in phosphate minerals (Fig. 20e). Of the 274 minerals known from this pegmatite province 135 are phosphates, accommodating Na, Al, Ca, Ba, Mg, Mn, Fe, Sr, Be, Bi, Cu, K, Pb, Li, REE, Y, Sc, Zr, Ti, U, and Zn, as well as � uorine and hydroxyl groups in their lattice. They formed as primary and secondary phosphates and were generated during hypogene and supergene alteration of the pegmatites over quite a long period of time from the Carboniferous until the Neogene. 4.6.1. P pegmatites in the Variscan Metallotect 4.6.1.1. From pegmatites sensu stricto to plutonic pegmatites — zonation by crystallization and � uid/melt movement. The phosphate pegmatites of

the Hagendorf –Pleystein Pegmatite Province are located in the Moldanubian Zone along the western edge of the Bohemian Massif and in summary are classi�ed as (Sc–As–Be–Zn)–Li–Nb–P pegmatites (stock-like and tabular) as wellas aplites(tabular).All felsic mobilizates were emplaced in biotite–sillimanite gneiss which also gave host to a suite of sheet-like granites. Although not acting as a host, calcsilicates


and skarns are found in the close vicinity of the stock-like phosphate aplites and pegmatites. The most-well known Hagendorf-South Pegmatite whichwas mined intheCornelia Mine shows a zonationby crystallization that is more or less concentrically shaped with a thin aplitic zone at its margin being replaced towards the center by a zone of K feldspar and eventually by quartz (Fig. 7g). On top of this quartz zone the phosphate zone developed in Hagendorf-South and Hagendorf-North (Figs. 1a, 7g).

a

481

Uebel (1975) distinguished during his studies of the HagendorfSouth Pegmatite two generations of pegmatite, a “Younger Pegmatite” and an “Older Pegmatite”. Although his interpretation needs some revision, his polyphase concept of emplacement can be supported by new geological � nds in the area. A second aplitic zone evolved within the Hagendorf-South stock,marking a slighthiatusprior to the emplacement of the “Younger Pegmatite”. The latter formed in an unbalanced physical

d

e

b

c

f

Fig. 22. a. Lithium–cesiumore with lepidoliteand polluciteas themainmineralsfromBikita, Zimbabwe.b. Lithium orewithlepidolite, Tanco/BernicLake,Canada. c. Lithiumoremadeup of

lath-shaped spodumene alteredinto cookeite. SapucaiaPegmatite, Brazil. d. Lithium oremade up of holmquistite.Koralpe Pegmatite,Austria (photograph:courtesy of R. Göd). e. Lithium phosphate ore made up of triphylite (dark) with older spessartite (red) in a matrix of alkaline feldspar and muscovite. Cigana Pegmatite, Brazil. f. Lithium phosphate ore made of amblygonite–montebrasite in a K feldspar matrix. San Elias Pegmatite, Argentina. g. Lithium mobilization along a NW –SE transect through the Saxo-Thuringian and Moldanubian Zones. For the geodynamic setting see also Fig. 9f (Saxo-Thuringian Zone = Fichtelgebirge Steinwald, Münchberg Gneiss Complex + Zone of Erbendorf –Vohenstrauss allochthonous part of the Moldanubian Zone, Oberpfälzer wald + Bayerischer–Böhmer Wald = Moldanubian Zone s.str.) Green shows the southward dipping nappe complex. Li –Si–(OH/F) = Li mica, Li–Al–P–(OH/F) = Li phosphate of the amblygonite–montebrasite s.s.s., Li–Fe–Mn–P = triphylite–ferrisicklerite s.s.s., Li–Si–B = Li tourmaline, Li–Si = spodumene–holmquistite. Boxes give Li contents in ppm.

482


g) Li-Si-(OH/F) Li-Al-P-(OH/F) Age Münchberg (Ma) Gneiss Complex

290 300 310

Fichtelgebirge-

Zone von Erbendorf-

Steinwald

Vohenstrauß

306

G3

129

G2

60

904-

n e i n m e á t k s ý z v u o e r ž K í / K

2130

G4

153

Bayerischer-Böhmer Wald

550

Li-Si-B

ř

e t i n a r G

G1

Pegmatite

340

Granitic fractionation zinnwaldite lepidolite granite pegmatite

Lamprophyre (min age)

Granite

Pegmatite

Granite

e t i n a r G d l a w n i e t S

Granitic fractionation

330

Granite

Lamprophyre (min age)

320

350

Oberpf älz er Wald

Li-Fe-Mn-P

i s e l d o P

280

Metamorphism Deep-seated lineaments + mantle impact

e t e i t n i a n r a G r G g r g e r b e n b e n t e h k c l u a e F L

+deep seated lineaments

105

amblygonite

65

Granite e t i n e a i t r G n a r g r G ü b u n a e n r s ä s B o l F

159

triphylite lithiophyllite tavorite sicklerite ferrisicklerite pegmatite

pegmatite

Collision zone

Pegmatite+ Aplite

Pegmatite e t i n a r G

47 33

Li-Si Metamorphic re-mobilization spodumene holmquisite pseudopegmatite


regime, as its melt came in contact with a cooler and semi-consolidated preexisting pegmatitic rock and gave rise to a funnel-shaped pipe mushrooming from the quartz core towards the top of the pegmatite stock (Fig.7g). This type of zonationis uni-directionalfrom bottom to top. The apical part of the quartz core and the feldspar resting immediately on top of it contain the Nb –Ta oxides, and the suite of phosphate minerals, containing Na, Al, Ca, Ba, Mg, Mn, Fe, Sr, Be, Bi, Cu, K, Pb, Li, REE, Ti, U, and Zn. In its footwall aplite, a section inaccessible in Hagendorf-South but exposed in some places at Pleystein, a phosphate mineralization with Al, K, Ti, Bi, Zn, Mn, and Fe, arranged in increasing order of abundance and less varied than the mineralization described above, was identi�ed in a zone pervasively kaolinized. This funnel-shaped vertical fading out of the quartz core or vertical “chimney” has much in common with the Sn-bearing siliceous greisen deposits at Altenberg and Sadisdorf in the Erzgebirge, Germany, located in the Saxo-Thuringian Zone and some of the Sn-greisens in the Cornubian ore Field — Section 4.1.1. This structural similarities strongly corroboratethe ideathat between siliceous Sn greisen depositsat rather shallow depth and quartzose P pegmatites at a deeper level is no real difference by quality but only by quantity. In the broadest sense, this structure may be explained with the so-called up-dip-effect of ascending hyper fusible-rich �uids sensu Černý (1991b). Thiscomposite zonation by crystallization and melt/�uidmovement is only represented within the stock-like pegmatites. The chimney or pipe structures become less conspicuous as the height of the accommodation space provided in the host anticline becomes reduced. The various associations of primary phosphates got “ telescoped” into each other and disseminated among the Nb–Ta oxides of the columbite s.s.s. in this core-rimzone. The tabular pegmatites and aplitesare devoid

of anyzonation or “chimney” even if these pegmatite sheets steeply dip along the limbs of the host of the anticlines. Neither cells nor fronts of �uid movement could evolve in these narrowly-spaced phosphate pegmatites and aplites and, consequently they show neither a zonation by crystallization nor by melt/ �uid movement. Since the morphologies of the pegmatite stocks in the Hagendorf – Pleystein Pegmatite Province closely resemble each otherand the vertical siliceous ore shoots in these stocks are left untilted, it is reasonable to claim thatafter their emplacement onlyverticalmovements haveaffected these pegmatites and no folding had any effect on these pegmatites. 4.6.1.2. Phosphate pegmatites and associated pegmatites as a function of geodynamic setting — vertical facies changes. Along a NNW –SSE pro�le

through the Central European Variscides, perpendicular to the strike of the various geodynamic units, 128 pegmatitic and aplitic deposits were investigated and classi�ed according to the CMS classi �cation scheme (Table 8). Their chemical composition, andphosphate contents, in particular, varies considerably as a function of their geodynamic setting. The Rhenohercynian geodynamic unit a mirror image of rifting and folding with sediments and magmatic rocks undergoing very-low grade to low grade regional metamorphism is barren as to pegmatites at all. U/Pb single zircon dating by a Laser-ICP-MS of samples from the marginalfacies of the twomajor granites Brocken and Rambergshowed a concordia age of 283 ± 2.1 Ma forthe Brocken granite anda concordia age of 283 ± 2.8 Ma for the Ramberg granite (Zech et al., 2010). These ages are interpreted by the author of the review as follows. This crustal event is characterized by an extension andthinning of thecrust,a process unf avorable for the formation of pegmatites in a typical ensialic orogen.


a

b c

Fig. 23. a. Amphibolite-bearing lithiumore shoot mined outduring trial miningat thelith-

iumdeposit Koralpe, Austria(photograph: courtesy ofR. Göd). b. Alternating layers ofamphibolite and Li-bearing aplite, dipping towards bottom right in the underground gallery of the lithium deposit Koralpe, Austria (photograph R. Göd). c. Pseudopegmatites at the Brandrücken in the lithium deposit Koralpe, Austria (redrawn from R. Göd, 1989).

The Mid-German Crystalline High forms part of a suture zone extending from Mexico through Turkey, resulting from the late Variscan closure of the Rheic Ocean which opened up between Gondwana and Laurussia and took a wide range of Paleozoic sediments sourced from Baltica and from Gondwana. It is composed of high-grade metamorphic rocks and intrusive rocks of the granitic suite. The Bärenkopf granite is intersected by E–W trending muscovite-bearing pegmatite dykes with some samples of muscovites from these dykes yielding a K –Ar cooling

483

age of 333 ± 7 Ma ( Neuroth, 1997). Pegmatoids and pegmatites are rare and only contain some apatite in the Spessart Mts. The Münchberg Gneiss Complex, as part of the Saxo-Thuringian Zone, is an allochthonous metamorphic complex with paragneisses, orthogneisses, amphibolites and eclogites (Fig. 9f). The orthogneiss yielded a Rb/Sr whole rock age of 499 ± 20 Ma ( Söllner et al., 1981). U/Pb age dating using zircon and monazite from metagabbros and metagranites gave an age of intrusion around 500 Ma for both intrusive rocks (Gebauer and Grünenfelder, 1979). Its metabasic members contain numerous pegmatoid deposits, yet barren as to phosphates. The color code of the Münchberg Gneiss Complex shown in Table 8 is similar to that of the Zone of Erbendorf Vohenstrauss in the NW Oberpfälzer Wald because both units once formed a coherent nappe complex (Fig. 9f). The Saxo-Thuringian Zone saw its pegmatites, granite –pegmatites (miarolitic) and pegmatite–aplitesconcentrated in andaround the Fichtelgebirge –Erzgebirge Anticline. Phosphate minerals, prevalently U phosphates, increased relative to those pegmatitic rocks being located to the North-West of the widespread granites in this unit (Table 8). Th geodynamic unit under consideration is the frontal part of the sub�uence zone with the main geodynamic processes relevant for the formation of pegmatites involving continent –continent collision and gradual thickening of the crust. Immediately south of the Saxo-Thuringian Zone the autochthonous parts of theMoldanubian Zone get in contact with theZoneof Erbendorf Vohenstrauss which is equivalent to the Tepla–Barrandian Zone (Fig. 9f).In other words, it is thetransition zone between allochthonous and autochthonous parts of the Variscides (Table 8, Fig. 2a). Strong diapthoresis and shearing is common in this contact zone between the Saxothuringian and Moldanubian zones sensu lato. The number of pegmatitic rocks rises and the chemical quali �ers of the rare element pegmatites and aplites become more variegated. While graniticpegmatites gradually disappear from the scene, the number of Fe-, Mn-, Zn-, Al- and even Li phosphates, increased in the pegmatites but did not yet reach this level known from the locus typicus for thephosphate pegmatites at Hagendorf –Pleystein. The allochthonous Zone of Erbendorf Vohenstrauss, a nappe complex overriding the autochthonous Moldanubian Zone, is some kind of a relapse as far as the distribution and type of the pegmatitic rocks is concerned. It is a very complex lithology found today in an allochthonous position, derived from suboceanic mantle, endowed with ocean ridges and also showing signs of within-plate magmatism with subsequent rifting. The chemical quali�ers of pegmatitic rocks are similar to those of the barren rocks from the Münchberg Gneiss Complex but with a slight impact of the autochthonous Moldanubian zone underneath. Therefore it is not a surprise to � nd a moderate increase of the phosphate content in the meta-pegmatites,pegmatoids and pegmatites of the Zoneof Erbendorf Vohenstraussrelative to the MünchbergGneiss Complex. The Moldanubian Zone sensu stricto consists of high grade metamorphic rocks in an autochthonous position with a protolith mainly of Proterozoic age. At the margin these units are overthrusted onto adjacent geodynamic units (e.g. Moravo-Silesicum) and penetrated by multiple intrusions of the granitic suite but also of mantle-derived melts, some of which are now present as syenitic rocks (Dill, 2015). The geodynamic setting is characterized by a signi �cant increase in phosphate andalso in boron, both of which can be taken as marker elements for the inner zone of an ensialic orogen and held to be crustal-derived. Their accumulation goes along with thrustal movements, stacking of nappes, and element mobilization in the course of anatectic processes in the deepest parts of the thrust planes, close to the root zones. The Hagendorf –Pleystein Pegmatite Province is located at the root zone of the nappe complexes thrusted onto the north-western geodynamic realms (Dill, 2015). The southernmost part of the Moldanubian Zone shown in bright green in Table 8 is the core zone of the Central European Variscides.

484


Boron and phosphate are still predominating in the southern Moldanubian. Both elements are so-called geodynamic proximity indicators in pegmatites as to the geodynamic center. Boron signals an emplacement closest to the core zone and the ultimate stage of thickening of the crust, whereas phosphate denotes a more distal position with a thickening of the crust less intensive than for boron. The Variscan massifs of Central Europe got incorporated into the modern fold belt of the Alpine Mountain Range and were reactivated in these fold belts. With regard to the distribution of the pegmatitic and aplitic rocks, Variscan Massifs in the Austrian Alpine Mountain Range in the Kärnten–Steiermark border region, deserve particular attention, where granitic pegmatites, meta-pegmatites, pegmatoids exist and pseudo-pegmatites become economic deposits(Table 8). The gradual increase of P and B towards the core of an ensialic orogen suffers a

setback when being reactivated in a new mobile belt. Phosphate and boron are both present but no longer take such a prominent position similar to the parent crustal section from which they originated (Table 8). They are only second- and third-most in abundance, with phosphate showing a higher preservation potential during this kind of orogenic reactivation than boron. TheNW–SE transectacross the Central European Variscides with the extension across the boundary into the Alpine Mountain Belt illustrates the variation of phosphate and its chemical ally in this ensialic orogen boron as a function of the geodynamic setting, a change which also implies a variation in the physical –chemical regime. It would go beyond thescope of this reviewfocusedon thegeology of pegmatites to address these changes of the physical–chemical regime. As far as the Central European Variscides are concerned this issue has been addressed in

b a Weathering +overburden Amphibolite Li zone (high grade) K feldspar zone Mafic intrusive sill Li zone (low grade) Na feldspar zone (Sn/Ta) Border zone +pegmatite undifferentiated

c

Fig. 24. a. Cross section through the Greenbushes pseudopegmatite, Australia, based upon drill holes plotted in the image which is modi �ed from a cross section in Kippenberger et al.

(1988). b. Cross section through the Bikita pegmatite, Zimbabwe (modi �ed from Pelletier, 1964). c. Longitudinal section through the Bernic Lake (Tanco) pegmatite, Canada (modi �ed from Laznicka, 2010, after Truemanand Turnock, 1982). d. Mined outspodumene orein thetabular pegmatite ofCachoeira, Brazil.Red arrowhead denotes layers ofspodumenepegmatite parallel to the contact withthe mainore shoot. e. Post-mineralizationfaultingand syn-mineralizationboudinageof contact-parallel pegmatite layersat Cachoeira Li deposit, Brazil. Birofor scale. f. Lath-shaped brown spodumene crystals are aligned subparallel to the contact of the ore shoot. Cachoeira Li deposit, Brazil. Biro for scale. g. The Varuträsk Li pegmatite, Sweden (modi�ed from Quensel, 1956).


d ca.1m

e

f

g Cs replacement Li replacement Core Zone Intermediate Zone External Zone Amphibolite

50 m


Dill (2015) based upon more than 250 minerals determined in the pegmatites and aplites along the western edge of the Bohemian Massif. 4.6.1.3. Phosphate pegmatites as a function of the geodynamic setting — lateral facieschanges. To what extentcan we apply this zonation of phos-

phate in pegmatites elaborated for Central Europe also to the western branch of the European Variscides on the Iberian Peninsula (Fig. 2a, Table 9)? The Mid-German Crystalline Rise has been referred to as a suture zone of global extension, where the emplacement of pegmatites and pegmatoids began along the NW –SE from the very-low grade to the high-grade metamorphic zones of the Central European Variscides (Table 8). It can be used as a “ geodynamic marker horizon” in order to correlate the eastern and western branch of the European Variscides. In Portugal and Spain, the Ossa-Morena Zone is held to be equivalent

485

to the Mid-German Crystalline High which was referred to as European Crystalline Zone by Kopp and Bankwitz (2003), owing to its prominent role and enormous extension. On the Iberian Peninsula this zone is rather poorlyrepresented in terms of pegmatitic rocks compared with the adjacent geodynamic zones there. Only granitic aplites andpegmatites with spessartite but devoid of rare element-bearing minerals, were reported from pegmatite veins cutting the S. Geraldo Tonalite and medium-grained biotite–muscovite granite (Lima et al., 2009). The geodynamic setting and the abundance in pegmatitic rocks closely resembles its Central European counterparts several thousand kilometers to the NE. The South-Portuguese Zone, being located to the South of this geodynamic unit is correlated with the Rheno-Hercynian Zone in Mid Europe. It is barren as to pegmatites as it is the case with its Central European analogue. The Central Iberian Zone being located immediately to the north of the Ossa Morena Zone is presumed to be the westernprolongation of the Moldanubian Zone, while the West Asturian-Leonese Zone being located further towards the north is to some extent an equivalent of the Saxo-ThuringianZone in Central Europe.Ribeiro et al.(1990) investigated a geotraverse along the Central Iberian Zone, delineating allochthonous, parautochtonous and autochthonous units similar to what has been recorded from Central Europe and interpreted the stacked pattern of nappes in terms of a �ake tectonic — see Fig. 9f. Many of the Variscan pegmatite � elds in Portugal and Spain are enriched in phosphate minerals, mainly accommodating lithium in their lattice: Almendra Pegmatite, NE Portugal (Li–F–P–(LiS)),Alvarrões Pegmatite (Central Portugal) (Li –F–P–(LiS)), Barroso–Alvão pegmatite �eld, Vila Real District, Portugal ((U –Zn–Be–REE) –Sn–Nb/Ta–Li–P), Assunção Mine, Viseu District, Portugal ((F –Mo–Bi–Cu–W–Sn–B)–Li– U–Nb/Ta–Be–P). The mineralized areas are encountered in those geodynamic units that are correlative in geodynamic terms with the Moldanubian and Saxo-Thuringian zones in Central Europe (Neves, 1960; Bertelli et al., 1982; Marzoni Fecia di Cossato and Orlandi, 1986; Noronha, 1987; Roda et al., 1996, 2004; Roda-Robles et al., 2013; Fuertes-Fuente et al., 2000; Martins et al., 2011: Alves and Mills, 2013). From ENE towards the WSW perpendicular to the strike of the geodynamic units, the phosphate contents increase while the chemical composition of the phosphate minerals becomes more varied. In the Cañada pegmatite in Castile and Leon, Spain, the phosphates belong mainly to thegroup of Al-, Fe-, Mg-, Mn-phosphates in places with alkaline andearth alkalineelements. Where lithium adds up to thechemical composition of the pegmatites, triphylite [LiFePO 4], ferrisicklerite [Li(Fe,Mn)PO 4] and montebrasite [LiAl(PO4)(OH)0.75 F0.25] came into being, a sequence well-known from the Saxo-Thuringian–Moldanubian transition. The montebrasite–amblygonite s.s.s. decreases, while the Fe and Mn increase in the Li phosphate of the pegmatites sensu stricto. The chemical composition that most closely resembles the phosphate association in the pegmatites of the Hagendorf –Pleystein Province evolved in theBendada andMangualde areas in Portugal, at thewestern edge of the Iberian Pegmatite Ore Field (Table 9). At Hornachuelos, Córdoba, in Andalusia, the pegmatites may be denominated as (B –F)– Be–Nb/Ta–REE–U–P pegmatites. If the North Atlantic Ocean had not come into existence during the Early Cenozoic, we would not have to talk about a Late Paleozoic Iberian and New England pegmatite province, including discrete pegmatite areas in Maine, New Hampshire and Connecticut along the eastern coast of the USA. The pendant to the Variscan orogeny is called the Alleghanian or Appalachian orogeny that formed the Appalachian and Allegheny Mountains (Bartholomew and Whitaker, 2010). During the aforementioned mountain-building processes, North America which was part of the Euramerica super-continent collided with Gondwana resulting in the newly formed super-continent Pangaea a process which has been repeatedly discussed in this study for the European Variscides and, thus, need not reiterated here (Fig. 2b). It is after all not really a surprise to �nd a wide range of phosphate minerals to prevail among the accessory minerals of the New England pegmatite province (Cameron et al.,1954; King, 1975; King and Foord, 1994; Simmons

486


2 cm

2 cm qz

ms

kf

a

nf b

c Fig. 25. a. Dark gray sprays of columbite-(Fe) at the contact in the K feldspar pegmatite rim. The bundle of columbite-(Fe) plates grew post-kinematically. Hagendorf-North Pegmatite/

Meixner Mine, Germany (photograph: B. Weber). b. Dark plates of columbite-(Fe) developed at the contact between the albite rim (nf) and a muscovite (ms)–quartz (qz)-enriched zone in the pegmatite rim. Part of the plates grew unaffected, part of the columbite plates are bent and developed late-synkinematically. Hagendorf-North Pegmatite/Meixner Mine, Germany (photograph: B. Weber). c. Thortveitite intergrown with orthoclase, Evje –Iveland pegmatite district, Norway.

et al., 1995, 1996; Moore, 2000; Nizamoff et al., 2007; Wise and Brown, 2010). Even if some differences in themineralogy betweenboth sidesof the North Atlantic Ocean cannot be sidelined, the dominance of phosphates is striking and even over such a wide distance the mineralogical resemblance between the Palermo Pegmatite—New Hampshire, USA and the Hagendorf –Pleystein Province—Oberpfalz, Germany cannot be ignored. By tracking this lateral facies change from East farther West across the ocean, the New Hampshire subprovince comes close to what we know from theMoldanubian Zone andthe Maine Subprovince comes close to the Saxo-ThuringianZone, as far as the pegmatite-hosted phosphate facies is concerned. Keeping in mind that the collisional belt swang towards the SE in the Moroccan Little Atlas, the geodynamic zonation in NE America is a mirror image of the Iberian Peninsula. The

geodynamic control of the distribution of phosphate in pegmatites by quality and quantity points to a crustal origin of this rare element in pegmatites. It was mobilized by anatectic processes along with thrustal movements. Anatectic pegmatoids are at outcrop in the V ěžná 5 pegmatoid, Czech Republic, and the Strontium Granite, Great Britain (Fig. 21a, b). In-situ formation of pegmatitescan also be observed in amphibolites, as exempli �ed by the pegmatoid schlieren produced by anatectic processes between 910 Ma and 915 Ma near Iveland Village, Norway (Fig. 21c). Rare-metal pegmatites frequently observed in or near metabasic or even metaultrabasic rocks should come as no surprise, and what started as an in-situ pegmatoid like that in the Fig. 21c may end up as a (pseudo)pegmatite elsewhere in a nappe or a shear zone, as recorded from many sites in this study — see also the rare-

487


60.00

90.00

) a T + b N ( / 0 0 1 * a T

50.00

magmatic

tabular pegmatites

D2 80.00

Reinhardts -rieth II

Pleystein New Aplite

D1

40.00

high 30.00

20.00

10.00

N O I T A N O I T C A R F low

A

C

(meta)-pegmatites

Silbergrube

Reinhardts -rieth I

HagendorfSouth Trutzhofmühle

meta-pegmatites HagendorfNorth

1

Püllersreuth

PleysteinKreuzberg

D3

m e t a m o r p h i c

stocklike pegmatites

2 3 0.00 0.00

B

10.00

4 20.00

Mn*100/(Mn+Fe) 30.00

40.00

50.00

60.00

Fig. 26. Cross plot toshow the Ta2O5 ∗ 100/(Ta2O5 + Nb2O5)vs.MnO ∗ 100(MnO + FeO)of columbite s.s.s. from metamorphic to magmatic columbitemineralization (modi�ed from Dill,

2015). The data arrays of the tabular and stock-like pegmatites of the HPPP are given in the rectangular boxes. The framed boxes and the data symbols are plotted in the same color (e.g. Hagendorf-South in red). Area framed with dash-point lines terminated the data arrays of columbite s.s.s. included in “ nigrine” (see Section 4.9) 1: Deggendorf “ nigrine” in gneiss, 2: Deggendorf “nigrine” in alluvial–�uvial placer deposits, 3: Iglersreuth “nigrine” in alluvial–�uvial placer deposits, 4: Pingermühle: “nigrine” in alluvial–�uvial placer deposits. A gives the Pleystein trend, B the Hagendorf trend, C shows the data array of the pegmatites in the Bayerische –Böhmer Wald including data from the Hühnerkobel, Pochermühle, Blötz, Schwarzeck, Schwarzenbach, Birkhöhe, Pauliberg, Kautzenbach pegmatites (source: Schaaf et al., 2008). D1 and D2 are two discrete data arrays of columbite s.s.s. from Otov, Czech Republic, immediately E of the Czech –German border. D2 is located above Ta2O5 ∗ 100/(Ta2O5 + Nb2O5) = 60.00 and � t into the base diagram as to the MnO ∗ 100 (MnO + FeO) ratio 50.00 to 60.00. Data source: Masaryk University, Brno, Czech Republic. The trend lines of the various data arrays in the diagram follow two different trends as far as the Nb–Ta mineralization is concerned. I) an anticlockwise trendfrom metamorphic to magmatic felsic mobilizates (metapegmatites, intermediate (meta)pegmatites and magmatic felsic mobilizates). Such trends are recognized at Püllersreuth, Kreuzberg, Reinhardsrieth I, Trutzhofmühle (arranged in order of increasing magmatic impact, represented by the sl ope of the positive trend lines.II) A magmatic trend showing thedegreeof fractionationfromlow to high. Themost primitive columbitesevolved in the “nigrine” aggregates, with 1 and2 apparently derived from metamorphic processes and 3 and 4 signaling the initial level of magmatic fractionation.

metal pegmatite at 910 to 915 Ma in sharp contact with the metabasic country rocks in Fig. 4u. 4.6.2. Phosphate pegmatites reactivated in the Alpine Fold Belt

A study was conducted by Niedermayr and Göd (1992), listing the various minerals of the Weinebene lithium deposit in the Austrian Alps. The results obtained by both authors can shed some light on the issue whether Li–P pegmatites (Mn–Fe–Li phosphate) of the Moldanubian Zonein the CentralEuropean Variscides have lefttheir imprints on the newly formed Li pseudopegmatite (spodumene– holmquistite ≫ Mn–Fe–Li phosphate) in the Alpine Fold Belt. The authors mentioned a series of secondary Fe–Mn–Be–Ca phosphates �lling joints and fractures within the pegmatite and became of particular interest for mineralogists. These minerals re�ect a younger stage of alteration under a HPO24 −-enriched regime within the pegmatite and therefore are meaningless as to the question raised above on a reactivation. Green apatite, also widespread within the pegmatites of the Oberpfalz, Germany, triphylite and ferrisicklerite are exclusive to the massive amphibolite-hosted pegmatite that underwent only weak deformation. The authors attribute these minerals to the so-called “Altbestand ” (relic or armored minerals) apart from spodumene, quartz, feldspar and mica. In addition to these major minerals

some minor constituents such as beryl, schorl, galena, cassiterite, pyrochlore, sphalerite, and columbite-(Fe) were also ranked among the “ Altbestand”. Niedermayr et al. (1988) emphasized in their paper theabnormally high amountsof Mn inthe phosphates which isalsotypical of the Moldanubian counterpart pegmatites. Garnet is present as almandine-type in the mica schist-hosted pegmatite of the Austrian lithium deposit. Spessartite-enriched end members associated with manganiferous apatite have not yet been reported. Based upon this partitioning of Mn between silicate and phosphate in favor of the last-mentioned mineral, a source pegmatite at a rather shallow level of intrusion is assumed for the Weinebene pegmatite. As far as the physical regime is concerned, the minerals of the triphylite–lithiophyllite series, which form part of a hightemperature series in pegmatites have a good preservation potential in the reactivated pegmatitic rocks. 4.6.3. Phosphate pegmatites in the Proterozoic Metallotect in Africa and South America

The East African fold belts are not characterized by a wealth of phosphate-bearing pegmatites. In some cases phosphorus is present in signi�cant amounts but seldom forms the prevailing rare element in the pegmatite, as it is the case with the (B –Sn–REE–Li–As–Th)–P–U–

488


100

100

50

50

I 0

II 0

0

50

100

0

100

100

50

50

III

IV 0

50

100

0

0

50

100

0

50

100

Fig. 27. Mn ∗ 100/(Mn + Fe) ratio versus the Ta ∗ 100/(Nb + Ta) plots from Melcher et al. (2013). See for orientation and labeling of x- and y axes

also Fig. 26. I: Jos Plateau, Nigeria. II: Damara Belt, Namibia. III: Alto Linghoau, Mozambique. IV: Orange River, Namibia + Kamativi, Zimbabwe. Hel, Helicon; KR, Klein Rössing; MR, Mon Repos; Otj, Otjimbingwe; Rub, Rubikon; So, Somipe; Wdg, wodginite. Arrows indicate fractionation trends in subgroups of analyses.

Be–Nb pegmatite at Kobokobo in Sud-Kivu, Democratic Republic of Congo (Sa�annikoff and van Wambeke, 1967; Van Wambeke, 1987; Piret and Deliens, 1987). Some smaller occurrences of phosphate pegmatites are also foundin Rwanda(Knorringvon, 1969; Fransolet, 1995). In western Africa, several phosphate-bearing pegmatites have been investigated by Keller (1985), Fransolet et al. (1986) and Baldwin et al. (2000). Although being worked for tin and lithium during the waning stages of their mining period, the Sandamap (B –Nb/Ta)–Sn– Li–P pegmatite, in the Erongo Region, Namibia, warrants mentioning for its phosphate minerals. Primary and secondary phosphate minerals endowed with Fe, Mn, Mg, Al, Ca and Li are of the same type as investigated in detail in the Hagendorf –Pleystein Pegmatite Province only recently by Dill (2015) even if they do not attain the variability and quantity as in Germany. The mineralized pegmatites are bound to the Damara Belt, the NE-trending inland branch of the Neoproterozoic Pan-African Damara Orogen — 523 to 506 Ma (Ashworth, 2014). Trace elements published by the above authors show that these pegmatites resemble syn- to post-collisional granites using the common x –y discrimination diagrams with Rb vs. Nb + Y on display. In the Damara Orogen, granites, pegmatites and amphibolite facies regional metamorphism were interpreted as a direct response to the closing of the Khomas Ocean as theKalahari craton subducted beneath theCongo craton (Kinnaird and Nex, 2013). While the data collection is �ne, the type of geodynamic plate motion is hardly in context with the mineralization associated with the proposed process. Pan-African pegmatites may without any doubt stand out among the mineral deposits in Africa, but whyare some enriched in phosphates and others do not contain this element? Von Knorring (1970) has already pointed to the pegmatites' diversity in the Damara Belt, Namibia, the Kibaran Belt of Central Africa and those of the Mozambique Fold Belt in eastern Africa. No timebound chemical composition typical of the Pan-African pegmatites can be observed when the entire southern Africa is considered.

Lookingbeyond the South Atlantic Ocean, the presence of phosphate pegmatites is less striking than in western Africa, although one of the pegmatite-hosted phosphate minerals was found in the Corrego Frio mine at Linopolis, Brazil, and named brazilianite after the country where the type locality is situated (Cassedanne, 1983). It is a (Be–B)– U–P pegmatite tabular in shape and aligned parallel to the schistosity of the Precambrian biotite–garnet schists. A tectono-thermal process accompanied by the emplacement of granitic batholiths and pegmatites took place at around 580 Ma in the Borborema Province creating about 50 phosphate minerals (Rodrigues da Silva, 1975; Beurlen, 1995; Da Silva et al., 1995; Fetter et al., 2000 ). As reference localities for the Borborema mineral province the Roncadeira pegmatite ((Zn–Be)–Sn– Nb/Ta pegmatite) and the Boqueirão pegmatite (Boqueirãozinho), Parelhas ((Be–F–U–Bi–Pb–Zn–Cu–B–Sn)–Li–Nb/Ta–P pegmatite) are presented here to demonstrate the usefulness of the designedclassi�cation scheme. But the ore minerals of interest are Nb/Ta-, Be-, Sn- and Libearing chemical compounds. The Brazilian Shield is much more endowed with tourmaline of gemological and showcase quality than with phosphate deposits of similar standard (Dill and Weber, 2013). In the Argentine part, the Tres Tetas Pegmatite in the El Quemado District is also enriched with phosphate and is placed in this section (U – B–Be–Bi–Li–P pegmatite) (Galliski and Černý, 2006). 4.6.4. Synopsis of P pegmatites

The distribution of phosphate pegmatites in Paleozoic orogens strongly contrasts with that of Neoproterozoic metallotects as exempli�ed by the Variscides which welded together Laurussia and Gondwana and the Pan-African or Brazilano Orogenies which acted in the same way some hundred million years earlier contributing to the built-up of Gondwana. The differenterosionallevels encountered in the pegmatites are obviously accountable for the distribution of phosphorus and its chemical af �liate boron.

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2cm

a

2cm

b

c

2cm d

0.5m

e

Fig. 28. a. Nativebismuth in a veinletcutting throughthetopazfels atSchneckenstein, Germany. Itis a �uorine-enriched brecciain the exocontactof the EibenstockGranite. It is genetically

related to the greisen-type Sn deposits nearby. b. Cassiterite-bearing Sn greisen in the strongly differentiated “Tin Granite” at Rudolphstein, Germany, with disseminated oxidized arsenopyrite (brown). c. Ferroan sphalerite ( “marmatite”) in quartz at Kreuzberg Pegmatite in Pleystein, Germany. d. Molybdenite deposit in an aplite vein (below trenched). The close-up view above shows the aplite with greisenized quartz veins (white + dark gray) mineralized with molybdenite. Allebouda, Sweden. e. Molybdenite pocketi n a granitic aplite. Kataberget, Sweden.

Phosphate-enriched metabiolites and metaphosphorites intercalated in some of the metasedimentary units cannot explain the presence or absence of P-bearing pegmatites. Amphibolites intercalated into metasedimentary units from the Central European Variscides have been analyzed fortheir P2O5 contents, yielding a mean of 0.26wt.%P 2O5. Apart from apatite with phosphorus contents around 40 wt.% P2O5, another rock-forming mineral merits to be mentioned. Although it contains P at a much lower level around 0.x wt.% P2O5 it is the most widespread mineral in the earth crust. The feldspar group, with K feldspar

is more likely a source of P than albite, and has to be envisaged as a potential source of P in pegmatites too (Breiter, 1998b). The phosphorus variation in granitic rocks has been among others studied by Broska et al. (2004) and treated in experiments by Tollari et al. (2006). The in�uence of the iron content and oxidation state on the saturation of phosphate minerals in magmatic systems have been studied by the latter authors in the temperature range from 1030 to 1070 °C. For the Mid-European Variscides, Förster et al. (1999) put forward a chemical subdivision of the granitic intrusive rocks into

490


a b

c

d

Fig. 29. a.

Sacharoidal zone in the Las Cuevas Pegmatite, Argentina, composed of almost 90% albite, muscovite and manganiferous garnet. b. Border zone of the La Viquita Pegmatite, Argentinain sharp contact tothe micaceous wall rocks.The borderzoneconsists of K feldspar, quartzand albite.Muscovite grewperpendicularto thecontact plane. Thefeldspar-enriched pegmatitespenetrated in some kindof a horse-tailing thePaleozoic mica schistparallelto thefoliation (arrowhead). c.Intermediate zone ofthe Santa AnaPegmatite made upof K feldspar. d. Sheared K feldspar zone, disrupted into phacoids of feldspar and quartz with muscovite as “lubricant” La Viquita Pegmatite.

(1) medium-F and low-P biotite granites (A-type), (2) high-F- and low -P lithium mica granites (A-type), (3) h igh-F- and high-P lithium mica granites (S-type), (4) low-F — two-micagranites (S/I-type). The various granites enriched in P and Li failed to be correlated in time and space with any large Li-phosphate pegmatite. The P content of garnet-group minerals could also achieve rather high values of as much as 1.21 wt.% P2O5, but to quote the authors themselves, “the partitioning of P among garnet and its associated minerals in granitic systems remains still unclear” (Breiter et al., 2005). It is a hint towards the role the lithology in andunderneath a pegmatitic ore �eld can playin the presence or

absence of phosphate-bearing pegmatites — see also the section on garnet pegmatites (Section4.14). Contrastingcrustallithologies in Paleozoic and Precambrian collisional orogens could plausibly account for the prevalence of boron over phosphate in pegmatites. 4.7. Lithium–cesium–rubidium pegmatites (15 D)

Potassium and sodium are common elements in pegmatites and belong to the “ top-ten-elements” in the crust with 20,900 ppm K and 23,600 ppm Na. Both elements are present in a wide range of rock-

491


forming minerals, in pegmatites, mainly in alkaline feldspar and mica. The average grade in the earth's crust of three other alkaline elements rubidium, lithium and cesium, also common to pegmatites, stands at 90ppm Rb, 20ppm Liand 2 ppm Cs, respectively. While Rb+ often substitutes for K+ in some of its minerals, rubidium minerals of its own such as rubicline (Rb,K)AlSi3O8 and voloshinite RbLiAl1.5Al0.5Si3.5O10F2 are rarities. This is also true for Cs minerals excluding pollucite which is common in some pegmatites (Fig. 22a). Lithium, however, occurs in a wide range of silicates, the most well-known of which are spodumene and holmquistite, a lithium amphibole, in Li tourmaline s.s.s. and in Li mica s.s.s. (Fig. 22a, b, c, d). They rank as ore minerals for lithium. This is true also for some Li-bearing phosphates such as triphylite andthe members of the montebrasite-amblygonite s.s.s (Fig. 22e, f). The abundance of lithium in different magmatic rocks leaves little room for another source than the crust: Ultrabasic rocks: 0.x ppm Li, basic rocks: 17 ppm Li, intermediate rocks: 20 ppm Li, syenite: 28 ppm Li, granite: 40 ppm Li.

4.7.1. Li pegmatites in the Variscan Metallotect

The lion share of pegmatites under operation in the Bohemian Massif in Central Europe is enriched in feldspar, quartz and mica and, consequently these mineral deposits were exploited as a raw material in use for ceramic products. Only lithium is known to have been mined as a by-product in the Hagendorf –Pleystein Pegmatite Province. This element is quite common in pegmatites from the Saxo-Thuringian through the Moldanubian Zone in a wide range of host minerals, and we can �nd lithium as a major component also in the ancient massifs, south of the uplifted Variscan blocks, incorporated and reactivated in the Alpine Mountain chain. Along the northern rim of the Bohemian Massif, in the SaxoThuringian zone,which is identical with thefrontal part of thenorthward moving nappes and the collision zone, the lithium micas lepidolite and polylithionite are widespread in the granitic pegmatites and the town of Zinnwald, Germany,became the namesake or locustypicus of zinnwaldite.

a

amp 10 cm

amp b

zoi

Fig. 30. a. Eclogite–amphibolites intersected by zoisite pegmatoids (white) at Weissenstein near Stammbach, Germany. b. Close-up view of the zoisite pegmatoid (zoi) surrounded by

eclogite amphibolite (amp). The green coating is made of lichen. c. Morphological expression of the feldspar pegmatoid–pegmatite at Shagaait uul in the WesternMongolian Steppe-(arrowhead). d.Outcrop of the intermediate graphic zone of the Khar Chuluut 2 Pegmatite. e. Contact between to textural zones in the core part of the Khotol us Pegmatite. f. Shape and zonation of the Shagait-uul quartz–feldspar pegmatoid-pegmatite in biotite–crystalline schists, gneiss,granite–gneiss andrarelyamphibolite.g. Mphungumica–quartz–feldspar pegmatoid, Malawi.

492


c

d

gr

bl = blocky central zone gr = graphic intermediate zone

bl

e Fig. 30 (continued).

Thelithium contents in thenorthernmostpart of theBohemian Massif increaseat a steady rate inthecourseof granite differentiation from 60ppm Li in the oldest member of this granite suite through 306 ppm Li in the most strongly fractionated “ Tin Granite” (Richter and Stettner, 1979). Heading further east towards the Erzgebirge/Krušne Hory Mts. shows a moderate lithium increase in the Nejdek Pluton/Eibenstock and in a similar way in the Slavkovský les/Kaiserwald, Czech Republic (Breiter, 1998a). Only the albite –Li–mica–granites with topaz are signi�cantly enriched in lithium, a fact that is mineralogically proved by the presence of the Li ore mineral zinnwaldite. The ultimate Li level is reached in the easternmost parts near Zinnwald, where medium-grained albite granites with zinnwaldite and lepidolite are exposed. Towards the South at the boundary between the Saxo-Thuringian and Moldanubian Zones, lithium is still present yet in a different chemical compound. It is accommodated into the lattice of montebrasite [LiAl(PO 4)(OH,F)] (Fig. 22f). There is no mineral any better to demonstrate the transitional character between the Li granitic pegmatites (Li

mica) in the Saxo-Thuringian and the Li pegmatites (Li phosphate) (Fig. 22a, b, e, f). Fluorine is the marker element for the Li-bearing granitic pegmatites and Li–Fe–Mn phosphate is typical of the northern part of the Moldanubian zone. The Hagendorf –Pleystein Pegmatite Province only contains Li phosphates, present as triphylite, lithiophyllite, tavorite, and ferrisicklerite. Approachingthe central parts of the MoldanubianZone, another level is exposed where lithium forms a chemical compoundwith boron, giving rise to the tourmaline s.s.s. elbaite and liddicoaite at Bližná I, Czech Republic, a pegmatite dike which intersects a calcite–dolomitemarble series (Novák et al., 1999a,b). The Rožná pegmatite near Bystřice nad Pernštejnem, is a large lepidolite-bearing pegmatite dike (Novák and Selway, 1997). The dike of the lepidolite pegmatite is located along the contact of theStrážek Moldanubicumand the SvratkaUnitand dominantly hostedby leucocratic biotite paragneiss. Apartfrom Li-mica it gave also hosttoaLichloritecookeite(Fig. 22c),togetherwith elbaite,amblygonite, and montebrasite. The depositsresides in granulitic to migmatiticbiotite–


f

Shagait uuluul pegmatoid-pegmatite Shagait pegmatite area

N S

20

0

20 40m

Aplite vein Blocky and graphic pegmatite

Quartz vein

Graphic pegmatite

Quartz tourmaline vein

Blocky pegmatite

Gneiss+amphibolite

g Fig. 30 (continued).

493

494


b

beryl

columbite

deformed

a

8 cm

10 cm

deformed undeformed

10 cm

Fig. 31. a. Columbite in elbaite from the metapegmatite at Otov u Pobezovic, Czech Republic. The columbite (dark) formed late synkinematically in the tourmaline s.s.s. b. Two different

varieties of beryl developed in the same metapegmatites yet at different sites. Pale green beryl has been broken perpendicular to the axis of the prism. The fracture is healed with quartz (Meclovu Pobezovic). Another megacrystal ofpale mottled beryl is undeformed(Otovu Pobezovic). Allsamples arefromthe Mineralogical Department ofthe Moravian Museumin Brno, Czech Republic.

hornblende- and biotite gneisses. The V ěžná I pegmatite dike cutting through serpentinized lherzolite is abundant in elbaite, polylithionite, trilithionite, and lepidolite (Dosbaba and Novák, 2012). The Li accumulation and its chemical bonding is interpreted in terms of an intracrustal process within an ensialic orogen where the Li mineral assemblages vary as a function of thrusting, nappe stacking and anatectic mobilization. Along with a deepening of the thrust the lithium used to change its chemical compound as follows: Li mica Li–Al phosphate Li–Fe–Mn phosphate. In the core zone of the Bohemian Massif identical with the central part of the ensialic orogen, Li enters the lattice of tourmaline to form Li boron-silicates. At the opposite side of theBohemian Massifwe arefacedwiththe same geodynamicsetting.Unlike the thrustal planes at the northern edge of the Bohemian Massif which dip towards the South, those alongthe southern edge of the Bohemian Massif dip towards the North. The lithium accumulation and geodynamic setting in the Bohemian Massif along the northern collision zone constitutes themirrorimage of the southern boundary,with a slight but striking difference.In theNorth, thegradient is moderate with a gently dippingthrust plane andthe various diagnostic Li associationswellsplit apart from each other, in the south a more steeply dipping thrust caused the various Li association with Li mica Li–Al phosphate Li boron silicatesto be telescoped into each other (Novák et al., 1999b). The accumulation of the various Li minerals, strongly controlled by crustal processes, re�ects the inclination of the planar architectural element responsible for the mobilization of the Li-bearing felsic melt. The physical–chemical processes causing the mobilization of the elements and accompanying the kinematic processes are described as follows (Dill, 2015). They are basedon an extensive study perpendicular to the strike of the geodynamic units: Anatexis and granitic fractionation (Li mica), granitic fractionation and subcrustal mobilization along

deep-seated lineaments (Li–Al phosphate), subcrustal mobilization along deep-seated lineaments and high-grade metamorphism in the root zone of the nappes (Li phosphate), high-grade metamorphism (Li borosilicates). It is an asymmetrical physical –chemical paired belt of lithium concentration in the Bohemian Massif which well agrees with the �ndings obtained for phosphorus (Section 4.6) and boron (Section 4.5) both of which are recycled within the crust.

⇒

⇒

⇒

⇒

4.7.2. Li pegmatites in the Alpine Metallotect

From the Austrian Alps four Li-bearing pegmatitic deposits are described in more detail (Angel, 1933; Angel and Meixner, 1953; Alker, 1972; Göd, 1978, 1989; Ucik, 2005 ). Near Spittal, at Erling a Li pegmatite (spodumene) is intercalated into micaschists. The Wildbachgraben pegmatite is a U–Sn–Nb–Be–Li pegmatite (spodumene) with beryl, ilmenorutile and scheelite. At St. Radegund near Graz a B–Be–Li pegmatoid (spodumene) formed within gneiss and micaschists. A variegated spectrum of Be minerals such as beryl, bavenite, bertrandite, and phenakite accompany the Li mineralization. In contrast to the Li occurrences mentioned above the Koralpe–Weinebene lithium deposit was explored by underground tunneling and drilling operations which are still going on (R. Göd pers. communication) (Figs. 22d, 23a, b, c). The Koralpe lithium deposit is an unzoned (Nb –B–As–U)–REE–P–Be–Li pseudopegmatite tabular (spodumene N holmquisite N Li phosphate) according to the CMS classi�cation scheme. The pegmatitic layers are intercalated into medium- to high-grade metamorphic rocks of the Koralpe which based upon their lithology can be subdivided into eclogitic amphibolites and kyanite-bearing micaschists (Göd, 1989). Emplacement of the pegmatites caused an alteration zone of several decimeter in thickness in thehosting amphibolites, andis characterized by biotitization and the formation of holmquistite. No contact phenomena exist along the


495

Fig. 32. a. Exhumed quartzcore of pinkish rose quartz(see inset) of theKreuzbergPegmatite in thetownof Pleystein,Germany.The feldspar rimhas been eaten away by erosion. b. Shear

zone �lledwithmilkyquartz. Itformspartof the “Bayerischer Pfahl” (GreatBavarianQuartzLode). Similarin their outward appearancebut smallerin size, quartzdikesof this typeare also found at the edge of the Hagendorf –Pleystein Pegmatite Province, some of which cross the border into the pegmatite provinces. c. Shear zone �lled with quartz from the bird's-eye view intersecting the Seigal Volcanics, Australia. d. Quartzdikes, aplites, pegmatites and granites in the Hagendorf –Pleystein Pegmatite Province, theboundaryof which is marked by a dashed frame. e. The distribution of silica-bearing gemstone deposits related to pegmatites by country and by geology. It is e xtracted from the map “ Gems and Gemstones by Country and Geology — Silica” (modi�ed from Dill and Weber, 2013). For legend see Fig. 10a.

mica schist-hosted dikes and no granitic intrusion is exposed in the area. According to the author above, the pegmatites could have been displaced from their source by tectonic events. Among the lithium minerals, apart fromspodumeneand holmquistite, montebrasite, triphylite,lithiophyllite and ferrosicklerite can be reported. Habler and Thöni (2001) dealt with the metapelites and metapegmatites intercalated into the crystalline basement of the Austroalpine nappe complex of the Eastern Alps. Their geothermobarometric investigations on gneisses of this Alpine basement section yielded temperatures around 600 °C at a pressure of 0.4 GPa. According to these authors the pegmatite formation can be correlated with

the low-pressure metamorphism in the metapelites, which based upon Sm–Nd-dating of magmatic garnet from the pegmatite gneiss is placed at 249 ± 3 Ma.Theirgeothermobarometric investigationsare in harmony with the quartz-saturated phase relationship of lithium aluminosilicates showing at this dataset spodumene to be the stable Li-bearing silicate (London, 2005). Subsequently, Thöni et al. (2008) �ne-tuned their previous petrological and chronological investigations suggesting a multiple emplacement of pegmatitic melts between 273 ± 2 and 258 ± 3 Ma, in some sites even younger with ages down to 251 ± 7 and, in places, around 230 Ma. Ensuing overprinting processes under eclogite-facies

496



conditions with peak temperatures around 700 °C and a pressure at 2.2 GPa accompanied by intense deformation during Cretaceous time, were unable to obliterate previous isotopic signals and to blur the magmatic nature of the aforementioned rocks. The chemical composition of the Alpine pseudopegmatitesresemblesthe chemicalcomposition of pegmatites in theMoldanubian Zone, being located to the North of the South Bohemian Pluton (Dill, 2015). Presumably a crustal section of the Moldanubian Zone similar in composition was reactivated in the Alpine Fold Belt. 4.7.3. Li pegmatites in the Precambrian, Paleozoic and Mesozoic metallotects

Judging by the outward appearance and by its structure, the Koralpe Li pseudopegmatite closely resembles the Greenbushes lithium pegmatite deposit ((U–REE)–Sn–Be–P–B–Cs–Li–Nb–Ta pseudopegmatite), Australia (Partington, 1990; Partington et al., 1995). The above deposit is described as a giant pegmatite [pseudopegmatite] dike of Achaean age with a substantial Li –Sn–Ta mineralization (Fig. 24a). It developed in a medium- to hightemperature and medium pressure regime with country rocks pertaining to the metabasic and metaultrabasic clan. Spodumene is the main Li-bearing mineral. The pseudopegmatite, being emplaced along a shear zone, was correlated with granitoids in the same tectonized crustal section which were envisaged as the parentalgranite but dated to be 90 m.y. older than the pseudopegmatite. The authors listed three major events to have controlled the concentration of the Li–Sn–Ta ore. At 2527 Ma the initial crystallization of the pegmatitic rocks and the metasomatism of the country rocks took place. Around 2430 Ma synkinematic and synmetamorphic hydrothermal alteration produced a second event, while during a subsequent deformation and metamorphism at ca. 1100 Ma the latest remobilization took effect. The spodumene mineralization within the Greenbushes deposit is the latest one placed outside the Na and K pegmatites ( Bettenay et al., 1988). The often cited fractional crystallization as the wayto pegmatites does neither add to the explanation of the origin of the Li

pseudopegmatite at Koralpe, Austria (Section 4.7.2) nor to that of the Greenbushes Li pegmatite. The ore body shown in the cross section of Fig.24a lookslikea rootlessintrafolialfoldwithinthe shear zone,a common feature of this type of deformation. Individual ore bodies found in the ore zone are not the result of differentiation of molten material but the result of folding and shearing. Another Nb–Ta–Li pegmatite is located at Wodginain Port HedlandShire, Australia ((REE–W)–Be–P–Li–Nb– Ta), in the Mount Cattlin Lithium Mine at Ravensthorpe ((F–Be–Sn)– Nb/Ta–Li (LiS N LiP)) and in the Olary Province, South Australia, (Be – REE–Li–P–Nb/Ta) (Lottermoser and Lu, 1997; Jacobson et al., 2007). The Li–Cs–(Rb) pegmatite, Bikita, Zimbabwe, is besides Bernic Lake (Lac-du-Bonnet), Canada, the only site where another alkaline element rubidium was found at such a high level so as to make its recovery from theore feasible (Dixon,1979) (Fig. 24b,c).AsynclinemadeupofArchaic ultrabasic and intermediate metavolcanic rocks in the Victoria Schist BeltgavehosttotheaboveLi –Cs–(Rb)pegmatite deposit. In thistabular strongly zoned deposit, whose mineral associationis subdivided into13 zones, spodumene is accompanied by zinnwaldite, lepidolite, petalite, as well as pollucite. An especially large array of lithium minerals is present in the pegmatite, with spodumene and abundant petalite in the upper intermediate zones and lepidolite in the lower intermediate zone as well as in the core, where it is of massive texture (Cooper, 1964; Kesler et al., 2012) (Fig. 24b). The host rocks surrounding the Bikita deposit are metasediments, serpentinites, dolerites, ironstones and epidiorites. Anatexis is the major mobilizing process during the evolution of the pseudopegmatite and a shear zone-hosted emplacement the most plausible way of accumulating lithium ore shoots of this size. In Madagascar analogue Na–Li pegmatites with spodumene, rubellite, a variety of the elbaite member of the tourmaline s.s.s. and rhodizite occur near Manjaka, Madagascar. The subhorizontal tabular Tanco pegmatite at Bernic Lake (Lac-duBonnet), Canada, has been subdivided into nine zones (Be –B–P–Sn– Li–Ta pseudopegmatite). The lower-intermediate zone is made up of microcline, albite, quartz, spodumene and amblygonite, the upperintermediate zone of spodumene, quartz, amblygonite and petalite,

497


. )

d e u n i t n o c (

2 3 . g i F

498


. )

d e u n i t n o c (

2 3 . g i F


499

a

b

5 cm

c

2 cm

Fig. 33. a. Nepheline syenite (white) intersecting an alkaline gabbro complex. East Carpathian Mountains near Ditró (Ditrău), Romania. b. Nepheline syenite with sodalite. Bancroft Area-

Oka-Blue Mountain, Canada. c. Blue sodalite from the nepheline syenite pegmatite at Dungannon, Ontario, Canada.

the pollucite zone contains pollucite and the lepidolite zone bears lithium mica(Selway et al., 2000, 2005). Zonation and structure have much in common with the Bikita deposits from Zimbabwe described previously (Fig. 24b, c). Basaltic and andesitic volcanic rocks are widespread in the area and form together with volcaniclastics the country rocks, while gabbros and diorites make up the immediate wall rocks of the pegmatite (Kremer and Lin, 2006). The Tanco gabbro, the Birse Lake granodiorite and the volcanic rocks of the Bernic Lake Formation developed more or less contemporaneously and form part of a singular volcanic and subvolcanic complex ca.2724 Ma (Kremer andLin,2006).Three different deformational phases can be identi�ed in the Bernic Lake area, encompassing isoclinal folding. According to both authors, the pegmatitic melt ascended from depth along the reactivated North Bernic Lake Shear Zone and was emplaced both within the shear zone and within rock units adjacent to it. The pegmatites intruded while the rocks of the Bernic LakeFormation were at or near the brittle–ductile transition, a situation quite common also in the ensialic

orogen of the Central European Variscides more than 2000 m.y. later along the thrustal zones between the Saxo-Thuringian and Moldanubian Zones. No strongly fractionated parental granitoid has been localized in the immediate vicinity and a tectonometamorphic process seems the most plausible cause for the emplacement of the pegmatite. Separation Lake area hosts the Big Whopper and Big Mack petalite pegmatites, the largest ore deposits among the 29 individual ore bodies considered by Breaks and Tindle (1997) as a genetic analogue to Bikita, Zimbabwe, which is classi �ed as (P–REE–Be)–B–Sn–Nb/Ta–Li pseudopegmatite (Li silicate). A detailed mineralogical investigation has been performed by Tindle and Breaks focusing on the Nb –Ta mineralization (2000a,b). A similar type of pegmatitic deposit as to the chemical composition is worked in the Koktokay No. 3 pegmatite (Altay No. 3 pegmatite), China (Zhang et al., 2004; Wang et al., 2006; T. Wang et al., 2007; R.C. Wang et al. 2007). There are, however, striking differences to the

500


a

b

2 cm

c

d

3cm

f

e

2cm Fig. 34. a. Andalusite fromthe Dolni Bory Pegmatite, Czech Republic. b. Sillimanite from the Marsikov metapegmatite, Czech Republic (specimen from the Moravian Museum, Brno). The

arrowhead pointsto chrysoberyl. c Kyanite lath intergrownwith mica atthe edgeof a pegmatoid.Zillertal, Austria.d. Hexagonal prisms ofblue opaquecorundumdisseminatedwithin the Dac Lac Pegmatite, Southern Vietnam. e. Sekaninaite (Fe-enriched cordierite) in a feldspar pegmatite, Dolny Bori, Czech Republic. f. Cordierite patches disseminated in an aploid (migmatite), Böhmisch Bruck, Germany.

aforementioned Li-enriched pegmatitic deposits as to the age of formation, which is early Mesozoic (200 Ma) and testi �es that the pegmatite is genetically unrelated to the wall granite (409 Ma). The pegmatite is one of the largest muscovite deposits in Asia and is most famous for its concentric-ring structure. The No. 3 pegmatite was formed in an early Mesozoicanorogenic extensional regime. A stable tectonicsetting wasassumed for the formation of the large pegmatite (Wang et al., 2007b). According to the information released on this deposit, a classi �cation as (REE)–Be–B–Cs–Nb/Ta Li-mica pseudopegmatite. It shows some features

also found in rare-element deposits along the East African rift and fold belts where pegmatites are closely associated with “ glimmerites” and may be taken as another example for the inter�ngering of mantle and crustal element concentration processes. In southern America a swarm of spodumene pegmatites makes up the Cachoeira pegmatite group in the eastern Brazilian Pegmatite Province and is mined for lithium (Romeiro, 1998; Romeiro and Pedrosa-Soares, 2005). Concluding from the mineralogical association, including montebrasite, spodumene, cookeite, columbite –tantalite,

501


Granite pegmatites Pegmatoids> metapegmatites

(kyanite)

andalusite

Pegmatites+aplites

(staurolite) (dumortierite)

NW

Frankenwald

MGC

Pegmatite(skarn)

Metapegmatites> pegmatoids

Fichtelgebirge

Z EV

sillimanite andalusite Oberpfälzer W.

andalusite cordierite

andalusite cordierite corundum

Böhmer WaldSE

HPPP

Fig. 35. A transect through thewestern edgeof theBohemianMassifto illustratethe variation of alumosilicatesand aluminum oxidesas a function ofthe geologicalsetting. See forfurther

explanation and distribution of pegmatitic rocks also the cross section in Fig. 9f.

cassiterite and beryl and the morphology of the ore bodies, the pegmatite may be called an unzoned (Sn –Be–P–Nb/Ta)–Li pegmatite tabular (Li silicate N Li phosphate). The individual pegmatitic ore bodies are arranged in an en echelon structural pattern within the Salinas Fm., where the individual ore lenses form sharp contacts with the cordierite–biotite–quartz schists and the subordinate intercalations of calcsilicate rocks (Fig. 24d, e, f). The pegmatite ore shoots followed the cleavage and discordant fractures of the metamorphic country rocks, whose deformation plan points to a strong lateral shear stress as the Li-enriched siliceous melt intruded the basement (Fig. 24e, f). Fluids like water and �uorine lowered the viscosity of the melt and provoked an increasing crystal size from bottom to top (Fig. 24f). The photographs in Fig. 24e and f showed lath-shaped spodumene crystals orientedparallel to thecontacts of thetabular bodies as a consequenceof �uid migration, the exocontact is characterized by boudinage and brittle deformation, features well known from pegmatites that late- to post kinematically were intruded into the HT-LP metamorphic rocks, as it is the case with the much younger pegmatites in the Hagendorf –Pleystein-Province, Germany.The resultsdescribed by the authors and the personal impression obtained at subcrop attests to metamorpho-tectonic processes accountable for the concentration of this lithium pegmatite. Differentiation is caused by a rheological process and unrelated to fractionation of a granitic batholith nearby. The classical Varuträsk zoned Cs–Li pegmatite in Sweden crops out in a metasedimentary series alternating with amphibolites (Quensel, 1952) (Fig. 24g). Its balloon-shaped body has different zones of Li c oncentration; several of its ore shoots in the external zone cross the boundary to the intermediate zone and one rims the core where the Cs content reached a maximum. Unfortunately, it cannot be deduced from the image whether the individual ore bodies in the endocontact zone have been affected by post-mineralizing faulting and so have splitted up the pegmatite into separate entities. In Finland, the Viitaniemi Nb–Be–Li–P pegmatite is hostedby a complexseries of leptites, leptite gneisses amphibolites, amphibole gneisses surrounding granites, granodiorites, diorites and gabbros (Lahti, 1981, 2000; Teerstra et al., 1993). Phacolites of Li pegmatite are squeezed into the surrounding micaschists. The micaschists are very rich in boron too, locally, exceeding by 30 times as much the boron content of common marine sediments.

Thebelt of spodumenepegmatites of theCarolina tin-spodumene belt in the USA is one of the largest reserves of lithium in the world (Kesler, 1976; Evans, 1978). The spodumene-cassiterite mineralization in the pegmatite resides in the Cherryville Quartz Monzonite, and in schists and amphibolites around it — Foote Lithium King Mts. (U –Nb/Ta–Sn– Be–Li–P pegmatite (LiSi N LiP)), Spruce Pine McHone Mine (B–Be–F–Li), Spruce Pine Chalk Ray Mica Mine (W–Li)–REE–Be–Nb/Ta–mica pegmatite. Individual lithium pegmatites were intruded parallel to foliation in the surrounding rocks with a surface dimensions from only a few meters to 90 m wide and 1 km long (Kesler, 1976; Kesler et al., 2012). It is an unzoned spodumene pegmatite with a spade of phosphate minerals among others kingsmountite, which was named after the Kings Mountains. The age of the pegmatites of the Foote Mineral Deposit falls in the interval 260 to 375 Ma. The structural pattern showing the individual pegmatites is not very much different from what has been described in detail from the Brazilian spodumene deposits in the previous paragraph, even if they are much older — see also Section 8. The outward appearance of tabular Li pegmatites may often give a differentpicture in plane viewand cross sectionsdrafted after mapping. Motion along these faults is mainly that of transform faults, mirrored at thesurface by en echelon felsic dykes. Accommodation space however is provided in the hinge areas and limbs of late anticlinal structures following therules of mimic tectonics, irrespective whether they are of Paleozoic or Precambrian age. As felsic to intermediate intrusive rocks are often cutby thelithium oreshoots,theseintrusive rocks can be attributed to a regional heat event together with the pegmatites but cannot be claimed as the heat source or parental granite for the Li pegmatites. The Manono–Kitolo and Kamativi spodumene-bearing pegmatites are structurally controlled and were described as some sort of “ mega �oors” in context with tin and tungsten in pegmatite together with the Sn–W deposits in Section 4.1.2 (Fig. 8a). 4.7.4. Synopsis of Li pegmatites

The Hagendorf –Pleystein Pegmatite Province is located at the heart of a region in SE Germany underlain by metapsammopelitic rocks whose age of metamorphism is older than 340 Ma. At the beginning of thepathway of Li concentration lies thepreconcentration of this alkaline element in the basement of the Moldanubian zone (Dill, 2015). While these metalliferous rocks or low-metal concentrations of lithium

502


are exhumed in the south, in the northern part, in the Saxo-Thuringian Zone, they are concealed at depth absorbed and recycled underneath the Li-bearing pegmatitic rocks at outcrop ( Fig. 22g). In the course of an anatectic conversion of crustal material into felsic magmas at depth there are sporadic magmatic processes of subcrustal origin, e.g., the formation of the redwitzites (intermediate intrusive igneous rocks) and the remobilization of metapegmatites along the boundary between the autochthonous and allochthonous units. These subcrustal basic rocks attest to a subcrustal heat source to be involved in the mobilization of the element from the metasediments.Bierlein et al. (2009) speculate on a large scale mantle –crust interaction in the lower crust. There is a strong geodynamical zonation from the frontal parts of collision zones to the root zones of nappes, where subcrustal heat may add up to the mobilization of Li. From thelower crustto theupper crust thelithium contents got gradually upgraded reaching its climax in the large highly differentiated Sn–W-bearing granitic batholiths along the Fichtelgebirge-Erzgebirge Anticline. Near the collision zone, lithium is found in Li silicates hosted by granitic pegmatites, whereas heading towards the core of the ensialic orogen, lithium becameenriched in phosphates and borosilicates. Concentration of Li and the emplacement of its pegmatites is closely linked to shear zones and thrusting, dismembered pseudopegmatites represent the ultimate stage of Li concentration in the course of reactivation in modern fold belts adjacent to ensialic orogens or older equivalent environments of deposition (Figs. 23c, 24a, b. c). Lithium has been derived from a crustal source and was also found reactivated within Alpine-type orogens (Fig. 6b). The often quoted zonation of pegmatite-related rare elements such as Li, Be, Cs and Nb/Ta in an onion-shell style round a hypothetical granite is neither supported by the cross sections of Sections 4.7.2 and 4.7.3 nor supported by mapping in the basement areas giving host to the Li pegmatites. Tabular and stock-like lithium pseudopegmatites were discovered frequently in metamorphic series composed of micaschists and mica gneisses alternating with meta(ultra)basic rocks. Albitization is a common feature of these pegmatites. Currently the hard rock lithium deposits in pegmatites are challenged by salars and inland playas enriched evaporites where lithium is recovered from brines. The idea is tempting but needs further testing as to the true nature of the parent material from which the meta(ultra)basic rocks have derived from. The micaceous schists and gneisses of the country rocks can be accounted for by claystones and mudstones. Magnesium- and calcium-enriched rocks like amphibolites mayhavederived froma basic volcanic protolith but canalsobe traced back to marls.The logic in this idea would pointto a metaplaya which the Li enriched pegmatites have derived from. If the metabasic rocks proved to be igneous in origin, strong contrasts in the rock strength between micaceous metasediments and massive metabasic rocks are accountable for the emplacement of Li pegmatites in these peculiar host rock suite. 4.8. Niobium–tantalum–scandium pegmatites (13 DE)

The average grade of niobium in the earth's crust is 20 ppm Nb, while the average grade of tantalum stands at 2.4 ppm Ta. Both elements have great similarities in their ionic radii (Nb: 0.69 Å, Ta: 0.68 Å) and occur in the same pentavalent state. They form minerals of complete solid solution series with the general formula AxByOz. The position A can be occupied by Na, Ca, Ba, Th, Pb, REE, Zr, Mn 2 +, and Fe 2+ , position B by Nb, Ta, Ti, Fe 3+ , Sn, Hf, W, and Al and position C by O, OH, and F. Niobium and tantalum develop niobates and tantalates, also containing considerable amounts of REE. The ionic radii of Nb and Ta prevent them from being accommodated in the structure of common rock-forming minerals such as feldspar or mica and leave these elements in solutions until the pegmatitic stage of alkaline and calc-alkaline magmas is reached, where they are accommodated in the columbite–tantalite s.s.s. (Fig. 25a, b). The second string to the

bow in Nb and Ta exploitation is the pyrochlore –microlite group which occurs mainly in alkaline magmatic rocks. Scandium can substitute in columbite-groupminerals and ixiolite to considerable amounts for Nb (Wise et al., 1998). Trivalent scandium is sometimes compared with Y 3+ and the trivalent REE with respect to its geochemicalbehavior (Wood and Samson, 2006). Themost common scandiummineral, the Sc silicatethortveitite is also known frompegmatite, e.g., the Evje–Iveland pegmatite district, Norway (Fig. 28c). 4.8.1. Nb/Ta pegmatites in the Variscan metallotect

Columbite–tantalite s.s.s. are common constituents among the mineralassemblagesknown frompegmatites andgranitic pegmatites in the Bohemian Massif. Along a NW–SE transect extending perpendicular to the strike of the Moldanubian and Saxo-Thuringian Zones from the Hagendorf –Pleystein pegmatites towards the granitic pegmatites of the Erzgebirge–Fichtelgebirge Anticline, in other words, from the central zone towards the collision zone, a conspicuous variation from columbite-only assemblages to tapiolite-dominated mineral assemblages can be observed. Tantalum increases in the columbite–tantalite s.s.s approaching the frontal parts of the collision zone or, in other words, up-dip of the thrust planes intersecting the Central European Variscides. These observationsin nature �nd also an outlet in some results elaborated during experimentalwork. According toAleksandrov (1963) and Linnen and Keppler (1997) columbite s.s.s. reveal characteristic changes in their chemical composition upon evolution of their host pegmatites, involving the Nb/Ta ratio to decrease along with fractionation. The experimental results of the aforementioned authors and the�eld relations described from the frontal part of the Saxo-Thuringian Zone in the Central European Variscides encouraged to a wider use the Fe + Mn- and Nb + Ta ratios in the columbite s.s.s. for a geological environment analysis of pegmatitic rocks (Fig. 26) (Dill, 2015). In the x–y plot of Fig. 26, displaying the Mn ∗ 100/(Mn + Fe) ratio versus the Ta ∗ 100/(Nb + Ta) ratio two different trends called the Pleystein- (A) and the Hagendorf Trends (B) can be observed. The data arrays of the stock-like and tabular pegmatites and aplites plot along these two steeply dipping trend lines. Both trend lines re �ect the magmatic fractionation in the Nb–Ta system of the columbite-(Fe) s.s.s. Mineral assemblages creating the Pleystein Trend A are located proximal to the thermal center, whereas those pegmatite mineral assemblages at a more distal position constitute the Hagendorf Trend B. The outward appearance and morphology of columbite from pegmatite sensu stricto can be deduced from (Fig. 25 a, b). The Püllersreuth Trend D 3 expressed by the subhorizontal trend line originated from the Fe–Mn fractionation in columbites hosted by metapegmatites. There are some data arrays coming close to this Püllersreuth Trend D 3 that were identi�ed in the Pleystein and Hagendorf data set (Fig. 26). Upon an extended examination of these peculiar data, these data arrays create an anticlockwise trend from metamorphic to magmatic felsic mobilizates (metapegmatites, intermediate (meta) pegmatites and magmatic felsic mobilizates) and they are recognized at Püllersreuth, Kreuzberg, Reinhardsrieth I, Trutzhofmühle (arranged in order of increasing magmatic impact, represented by the slope of the positive trend lines) (Dill and Skoda, 2015). D1 and D2 are two discrete data arrays of columbite s.s.s. from Otov, Czech Republic, immediately E of the Czech–German border. D2 is located above Ta 2O5 ∗ 100/(Ta2O5 + Nb2O5) = 60.00 and was � t into the base diagram as to the MnO ∗ 100/(MnO + FeO) ratio 50.00 to 60.00. These columbite trends from Otov belong to the metamorphic–magmatic trend illustrated in Fig. 26. The age of formation of the columbite s.s.s from the Otov metapegmatite in the Domažlice Crystalline Complex was constrained to 482.2 ± 13 Ma ( Glodny et al., 1998). The host metapegmatite of the Czech pegmatite deposits belongs to the same allochthonous nappe unit as the Püllersreuth metapegmatite (Tepla–Barrandian Unit). Mega crystals of muscovite from Püllersreuth datedby Glodny et al. (1995) yielded a cooling age of481± 5 Mawhich

503


a

c

b

pyrope almandine spessartite grossularite (+andratite)

d

2 cm

2 cm

f

di

ga

5 cm

gr e

Fig. 36. a. Well-shaped orangeMn-enrichedgarnet from anaploid(see inset with chemical composition).It shows a dodecahedral morphology with theedgesbeveledby theattrition.The

garnet hasbeen sampledin a drainage system intersecting theHagendorf –Pleystein Pegmatite Province. b. Red Mn-bearinggarnet in�ltrated along grain boundaries thequartz mosaicof the Ipe Pegmatite, Brazil. c. Feldspar with deep red spessartite and greenish opal (supergene alteration). Radkovice Pegmatite, Czech Republic (sample: Moravian Museum Brno, Czech Republic). d. Redporphyroblast of almandine-enriched garnet accompanied by black porphyroblasts of schorl in a metaapliteat Fuchsenbergnear Pleystein,Germany. e. Garnet–diopside skarn at Žulová, Czech Republic (di = diopside, gr = garnet, ga = gabbro). The gabbro was formed from desilici �cation of diorite pegmatite (sample: Moravian Museum Brno, Czech Republic). f. Well-shaped hessonite garnet from the garnet–diopside skarn at Žulová, Czech Republic (see Fig. 36e) (sample: Museum Masaryk University Brno, Czech Republic).

agrees well with the age of formation of columbite from Doma žlice Crystalline Complex. A specimen of columbite s.s.s. from the metapegmatites of the Domažlice Crystalline Complex is on display in the Museum at Brno, Czech Republic (Fig. 29a). Columbite precipitated late synkinematically to post-kinematically in this metapegmatite. How can the data arrays of the contemporaneous columbites from the Püllersreuth and Otov metapegmatites interpreted in terms of

their geological environment?Püllersreuth is the mostprimitive columbite s.s.s. which cameinto existence under truemetamorphic conditions in the metapegmatites. The columbite from the Otov metapegmatite is more strongly fractionated and more evolved than the Püllersreuth columbite s.s.s. It is takes a transitional position from metamorphogenic to magmatic. The strong differentiation within the Mn–Fe ratio in the metamorphogenic columbite is supposedly affected also by the

504


presence of metamorphogenic minerals scavenging Fe from the systems, such as members of the tourmaline and garnet s.s.s. which are common accessoriesin manymetasedimentary rocks. The sameconclusion can be drawn from thedataarray of thecolumbite s.s.s.found in the pegmatites sensu stricto of the Bayerische–Böhmer Waldincludingdata from the Hühnerkobel, Pochermühle, Blötz, Schwarzeck, Schwarzenbach, Birkhöhe, Pauliberg, and Kautzenbach pegmatites (source: Schaaf et al., 2008). The data array C framed with the stippled line has a strong magmatic component like their equivalent minerals from Pleystein and Hagendorf pegmatites in the northern part of the Moldanubian Zone and a moderately well developed metamorphic component. The emplacement of the pegmatitic rocks in the Central European Variscides is not a monophase process but runs the gamut from metamorpho-tectonic syn- to late kinematic mobilization through post-kinematic mobilization as far as the primary mineralization in the rare-element pegmatitic rocks is concerned. The differentiation of the Nb–Ta and Fe–Mn ratios in the columbite s.s.s. can be used as a tool to localize the Nb –Ta concentration in terms of the geodynamic

evolution and geological environment. These data are in full agreement with the evolution of the ensialic orogen and the geodynamic siting of the various pegmatites in the Central European Variscides. Even the formation Nb–Ta oxides in the predecessors or low-metal concentrations of pegmatites foundin the exocontact of the pegmatites can be concluded from the x–y plot of Fig. 26. It is the columbite s.s.s in “nigrine”, a mineral aggregate of Nb-bearing rutile and ilmenite exclusive to the roof rocks and wall rocks of pegmatite-prone gneisses of the NE Bavarian Basement (Dill et al., 2007, 2014a). There are three different types of “nigrine”, with type B being the most important one in terms of the columbite evolution around pegmatites. Grains of “nigrine ”, categorized as type B, additionally contain inclusions of columbite-(Fe), pyrochlore, beta�te, ferroan sphalerite, pyrrhotite and Fe oxides. Type A and type C “ nigrine” are barren as to these inclusions and cannot genetically correlated with rare-metal pegmatites. Type B is early postkinematic and enriched in niobian rutile, rife with lots of inclusions, especially columbite-(Fe). It precipitated in the crystalline country rocks at temperatures around 600 °C and is concomitant with the nearby rare-element pegmatites between 302 and 311 Ma (Dill

a

b Fig. 37. a. Plate of muscovite from the Irchenrieth Pegmatite, Germany. b. Muscovite booklets in the rim zone of the Ooldin tsaagan tolgoi feldspar pegmatite, Mongolia. c. The stocklike

mica pegmatite at Kragerö, Norway (redrawn from Richter-Bernburg, 1950). d. The bilaterally symmetrical mineralization in the mica pegmatite tabular at Holene, Norway (redrawn from Richter-Bernburg, 1950). e. Layered pegmatites. Above: Unidirectional growth zones in the sill-like mica pegmatite at Hitterö, Norway. (redrawn from Richter-Bernburg, 1950). Below: Layered structures (line rocks) made up of quartz, K feldspar, plagioclase, garnet and biotite Evje area, Norway. (photograph: courtesy of A. Müller, Geological Survey of Norway). f. Quartz-, quartz –feldspar- and nepheline pegmatites in the carbonatite-hosted mica deposit (Dill, 2007). g. Biotit horse-tailing into K feldspar mega crystals near the hanging wall contact of the core zone underneath. Evje area (photograph: courtesy of A. Müller, Geological Survey of Norway).

505


Quartz+feldspar or quartz

e

Labradorite Aplite

Muscovite+biotite+tourmaline

K feldspar zone Muscovite zone

Gneiss+mica schists

Quartz zone Plagioclas zone

15 m

c 10 m

Quartz+muscovite Quartz or quartz+feldspar Gneiss+mica schists

d

5m

f g

Fault Dolomite veins Nepheline pegmatite Quartz pegmatite Aplite Quartz-biotite gneiss Garnet-hornblende gneiss Vermiculite rocks Glimmerite Biotite gneiss

N

100 m


506


a variation in the Fe –Mn ratio at the beginning of the pegmatite emplacement during the waning stages of the metamorphism. The “ hammer handle” steeply inclined towards the left is representative of the more or less intensive fractionation. Clusters of such data without further information on how and where the samples have been taken and published in the literature are dif �cult to discuss. The Scheibengraben pegmatite obviously has beenmorestronglyaffected by metamorphic processes than the Hagendorf (Trend-B) and Pleystein (Trend-A) pegmatites and is more akin to the pegmatites from the Bayerischer–Böhmer Wald (Trend-C) (Fig. 26). Its Mn/Fe ratio is much higher than in the western parts of the Bohemian Massif and is controlled by the coexisting minerals capturing the Fe from the pegmatitic system. The subsequent magmatic fractionation trend starts off from this high Mn/Fe ratio. The coincidence of trends at Scheibengraben, Czech Republic and the south-western Moldanubian Zone is not a surprise, as both of them are representatives of the core zone of the Bohemian Massif. Fig. 38. Graphite deposit Bogala, Sri Lanka, with steeply dipping graphite veins (from Dill,

2010).

et al., 2014a). These gneissic wall rocks of the pegmatites, hosting “nigrine”, contain the least fractionated or most primitive mineral grains of columbite-(Fe) (Fig. 26). Areas framed with dashed lines in Fig. 26 terminate the data arrays of columbite s.s.s. included in “nigrine” which have derived from gneissic host rocks and alluvial –�uvial placer deposits: 1: Deggendorf “ nigrine” in gneiss, 2: Deggendorf “ nigrine” in alluvial–�uvial placer deposits, 3: Iglersreuth “nigrine” in alluvial–�uvial placer deposits, and 4: Pingermühle: “nigrine” in alluvial–�uvial placer deposits. When the pegmatites were s tripped off their gneissic roof rocks, columbite-bearing “nigrine” was released into the drainage system today intersecting the pegmatites and their wall rocks. The Nb:Ta ratio of columbite-(Fe) from carbonatites is typically high ( Kressall et al., 2010). Mackay and Simandl (2013) reported Nb:Ta ratios averaging 50:1. It is accompanied by pyrochlore, a mineral rarely found in the pegmatites, proper, in the NE Bavarian Basement. The Deggendorf 2 is assumed to have derived from the mantle, while the remaining primitive columbite-(Fe) s.s.s. have been moderately altered by magmatic and/or metamorphic processes along with the emplacement of the ad jacent pegmatites within the crystalline basement rocks. As nowhere manganiferous Nb–Ta oxide s.s.s. were found, a strong impact by metamorphic processes on the “nigrine”-hosted columbite s.s.s. can be ruled out. Based upon thischemical environment and geodynamic analysis the evolution of these rare-element pegmatites can be postulated as follows. During an incipient stage mantle derived �uids similar to those related to alkaline and carbonatitic igneous rocks ascended and made accountablefortheNb –Ta oxidesin theexternal contact zone of pegmatites. Pegmatites evolvedfrom the interplay of element mobilization related to metamorphogenic and magmaticprocesses. The data clustering inthex–yplotof Fig. 26, their linear andanticlockwise trendsare a mirror image to what extent magmatism and metamorphism contributed to the built-up of rare-metal pegmatites bearing Nb –Ta oxides. Several pegmatites in the Central EuropeanVariscides have been investigated for their columbite s.s.s. and Nb, Ta, Fe and Mn plotted in quadrilateral cross plots having FeNb2O6 and MnNb2O6 at the bottom tie line and FeTa2O6 and MnTa2O6 forming the top tie line. The diagrams cannot directly correlate with each other but the relative abundance and the trends may be concluded from these diagrams, e.g., the Nb–Ta fractionation in columbite-group minerals from the Scheibengraben beryl–columbite granitic pegmatite, Maršíkov, Czech Republic (Novák et al., 2003). It has to be noted that these diagrams were mostly designed for comparison of various pegmatite deposits using one of the classi�cation schemes published in Section 3.1. Many of them show the “upside-down-negatively-skewed hammerhead”. The subvertical trend at very high Nb/Ta ratio (“hammerhead”) marks

4.8.2. Nb/Ta pegmatites in the Precambrian Metallotect

The highest density of data points in x –y plots displaying the Mn ∗ 100/(Mn + Fe) ratio versus the Ta ∗ 100/(Nb + Ta) ratio of Nb – Ta oxides can be found in the publication of Melcher et al. (2015) for the African pegmatite provinces. The authors provided mineralogical and geochemical data for the most important Ta–Nb–Sn phases includingca. 15,000 electron microprobe and9000 LA–ICP-MS analyses in the scope of a project devoted to �ngerprinting of con�ict minerals (M. Melcher et al., 2008; F. Melcher et al., 2008). The aim was to identify illegalbehavior in trading COLTAN and blocking such trade routes using a wide range of trace elements and chronological data. The approach taken for Nb–Ta minerals resembles the efforts taken to stamp out “blood diamonds”. Thereforethe geology of pegmatites and thecorrelation of the full chemical dataset with each mineral associations or the evolution of the pegmatite � elds was not paramount. In other words, the data cannot be interpreted in the same way as done for the Central European pegmatites, in the previous section. Nevertheless some of the Precambrian pegmatitic counterparts investigated by the group of authors show some striking similarities to the much younger pegmatites discussed in Section 4.8.1 and enable us to apply the principles elaborated for the Central Europe analogues which have also been studied in detail for their mineralogy andgeology also to some of the African pegmatite �elds as wellas try and �nd some support for the interpretation of the data conducted in the Central European pegmatite provinces (Figs. 26, 27). The Jos Plateau, Nigeria, cannot be handled as a pegmatite province in the strict sense and it is not in any case comparable to those in the eastern parts of Africa or the European Variscides. However, its Nb–Ta mineralization can contribute very much to the understanding of Nb– Ta mineralization in pegmatites due to its unspoiled mantle derivation of magmatic rocks. About 50 anorogenic peralkaline and alkaline ring complexes came into being on the Jos Plateau, where these magmatic edi�ces are representative of the Younger Granites. They were intruded into Precambrian basement rocks (Wright et al., 1985; Woolley, 2001a, b; Mücke and Neumann, 2006). The ore mineralization consists of Sn – W minerals and columbite s.s.s. concentrated in greisen-type deposits and albitites (Kinnaird, 1985). The chemical data obtained for the Nb – Ta oxides from the Jos Plateau, Nigeria, cluster in the same territory as the data array of the “nigrine ”-hosted Nb–Ta oxides in NE Bavaria (Fig. 27-I). In addition to this, there is a vertical trend of its data points intheMn ∗ 100/(Mn + Fe) versus Ta ∗ 100/(Nb + Ta) cross plot, fading out around Ta ∗ 100/(Nb + Ta) = 50. This pattern resembles the Pleystein Trend A (Fig. 26). The ideas put forward for the “ nigrine”hosted columbites in NE Bavaria, Germany, get another support as to their origin so as to be closely related to a subcrustal source. They have derived from alkaline magmatic rocks. The vertical pattern at Jos Plateauparallel to the y-axis is indicative of a strong magmatic fractionation similar to the Pleystein Trend. The latter, however, did not sweep

507


its way through unspoiled. The slight inclination and its higher kick-off point with data around Mn ∗ 100/(Mn + Fe) = 15 to 20 is caused by a moderate contamination by metamorphic and metasomatic alteration. Thepegmatite belts of theDamara Orogenare located within an ensialic orogen whose pegmatites formedbetween 490 and 510 Ma ( Jung et al., 2000; Tkachev, 2011). The Rubikon, Helikon (Cs –P–B)–Nb/Ta–Be–Li pegmatite (LiP + LIS), Uis, and Sesam pegmatites demonstrate an almost un-contaminated magmatic differentiation (Fig. 27-II). Unlike the columbites from the Jos Plateau and the “nigrine”-hosted columbite

the differentiation did not take place from an unspoiled mantle magma but took place within a crustal section characterized by a h igh pristine Mn background which lead in southern Africa to several Mn deposits in Namibia (Schneider, 1992, 2008). Even the “ Mandarin Garnet” or “Kunene Garnet” which were mined in the Marien�uss–Hartmannberge are attributable to such metamorphosed Mn-bearing rocks of probable sedimentary-exhalative origin (Dill et al., 2012a,b). Neoproterozoic manganese silicate ore horizons (manganese formations) are associated with the well-known banded iron-formations (BIFs). This sequence is

a

c b Si1

Si2

A1

2 cm 2 cm

d

A2 10 cm A1: Qtz+Msc>Kao A 2: Kao+Msc+Qtz Si1/Si2: Qtz Fig. 39. a. Bene�ciationplantwith kaolinpiledup in front ofthe crasher, BorboremaProvince, NEBrazil. b. Hypogenekaolinization affecting thefootwallapliteunderneath thequartz core

of theKreuzbergPegmatite at Pleystein,Germany. Qtz= quartz, Msc = muscovite,Kao = kaolinite. c. Kaolinizedaplite granite at Premhof-Lohma, Germany. d. Kaolinizedapliteat Weiss Mine near Pleystein,Germany.e. Cross sectionthroughone ofthe Uralian pegmatite-related emeralddeposit at thecontact between granitesand talc schists andtalc–actinolite schists, to illustrate the spatial variation of hypogene kaolinization (Redrawn from Fersmann, 1940 in Schneiderhöhn, 1961). f. Cross section through the Salpond Kaolin deposit (modi �ed from Kužvart, 1968), Ghana, derived from supergene alteration of a tabular pegmatite intercalated into mica schists.

508


e Granite

Pegmatite kaolinized + albitite

Biotite schist bearing emeralds

Talc schist + talc actinolite schist

Granodiorite + intermediate rocks

f

Red weathered mica schist

25 m

White kaolinized pegmatite Red-colored weathering Fig. 39 (continued).

sandwiched between super mature metaquartzarenites interpreted as a shoreface deposit derived from a cratonic basement and deposited under high-energy conditions (Buehn et al., 1992). The source of manganese and iron is proposed to have been situated in the deeper oceanic parts of the associated basin, caused by initial spreading in the Khomas sea and the formation of oceanic crust. In the reference area in Central Europe – Section 4.8.1 – we do not � nd these discrete high-Mn and high-Ta columbite s.s.s. In viewof the paleogeographic background information available, this magmatic differentiation in pegmatites is triggered by a comparatively thin crust, where the oceanic stage must not go far back in times. Manganese concentration, when traced back to its kickoff point in a pegmatitic system can also tell us something about the relative thickness of the crust, in which the pegmatites were embedded. It needs, however, to be viewed against scavenging process triggered by minerals associated with or emplaced prior to the Nb –Ta oxides. In the Hagendorf –Pleystein Pegmatite Province the study on Mn in the various minerals came to almost full circle, in some other regions the gap may be considered still wide. Pegmatite province in northern Mozambique, also known as the Alto Ligonha Province forms part of the Pan-African orogeny (Fritz et al., 2013). Several individual pegmatites are known from this province, which according to Cronwright (2005) have been derived from late- to

post-orogenic subaluminous to peraluminous A-type granites of PanAfrican age, an interpretation which can hardly be corroborated by the data published by Melcher et al. (2015) who have singled out some of the deposits and plotted their trends (Fig. 27-III). The Somipe deposit clustering in the �eld where A-type granites and mantle af �liates used to form seems to be closest to the primitive mantle derived mineralizing �uids — see previous examples from the Jos Plateau and the “ nigrine”hosted columbite s.s.s. for comparison. The remaining data clusters show a curved anti-clockwise trend also known from Central Europe where it is interpreted as a manifesto for a magmato-metamorphic development. Obviously the study as to the Mn distribution has not yet “come to full circle ” in this area. The Kamativi pegmatite, Zimbabwe, developed in the Magondi Belt around 1000 Ma (Fick, 1960; Gallagher, 1967; Rijks and Van der Veen, 1972; Petters, 1991 (see Section 4.1.2 for further structural details). The chemical composition of its columbite s.s.s. is almost identical with thecolumbite s.s.s named as thePleystein Trend.It is a stacked pattern of anticlines (stock-like pegmatites) with their limbs gently dipping away from the hinge zone (tabular pegmatites), quite similar in shape to the Paleozoic Pleystein deposits but not in size. The data pattern heralds a strong magmatic fractionation with a moderate metamorphic impact (Fig. 27-IV).


509

Benson No. 3 ((Be–F–REE–Sn–P)–Li–Nb/Ta pegmatite (LiS)) and the CasaVenturapegmatite (Be–P–Li–Nb/Ta pegmatite) belong to the same type. The Homestead pegmatite, Namibia, although similar in age to the Kamativi pegmatite, Zimbabwe, yielded quite a different pattern for the columbite s.s.s. which are very rich in tantalite in places ((Bi) –Be– Nb–Ta–Li–P pegmatite (amblygonite –spodumene). This is also true for the Majayahan deposit, Somalia, (Sn–Li–Ta pegmatite) which formed around 530 Ma and the deposits in the Man Shield in Sierra Leone that were emplaced during a late- to post orogenic stage around 2600 to 2850 Ma (Sn –Nb–Ta pegmatite) (Morel, 1979; Patrick and Forward, 2005; Küster et al., 2009). Provided thatthe datasetrepresents a continuous process, the trend would imply a magmatic–metamorphic evolution. I suspect a sequence of at least two processes of precipitation of Nb–Ta oxides, with the most Mn-enriched similar to the Damara-type (Fig. 27-IV). It is another hint to take caution that chemical analyses done without a proper link to the geological and mineralogical setting are a hard nut to crack when it comes to the interpretation. For �ngerprinting it may be suf �cient, for genetic interpretation, however I cast some doubt on it and are reluctant to go any further. It has to be noted, data sets discussed for Nb–Ta oxides in Sections 4.8.1 and 4.8.2 allow for placing constraints on the Nb–Ta systembut do notsay anything aboutother elements in thepegmatite. The element associations of the shear-zone-related or thrustbound pegmatites and pseudopegmatites can be pieced together in context with a full-blown geological and geodynamic analysis.

a

b

4.8.3. Sc pegmatites Person for scale Fig. 40. a. Pegmatite I runs conformably with the calcsilicate marbles. Pegmatite-skarn de-

posit at Naje, Nepal (photograph: courtesy of Mr. Tamrakar). b. Xenoliths of calcsilicate skarnwithin the pegmatite. Pegmatite-skarn depositat Naje,Nepal (photograph: courtesy of Mr. Tamrakar).

From theCentralEuropean groupof pegmatites only a fewexamples canbe mentioned to contain scandium at an elevated butstill minorand subeconomic level, such as the Königshain (P–U–F–Ag–Li–Sn–W–Pb)– Bi–Nb/Ta–Be–REE pegmatite, the Trutzhofmühle (Sc)–Nb–P aploid and the (Sc–Li–Nb–F–B–U)–REE–Be–P pegmatite dike at Schöllnach near Tittling, all of which are located in Germany. A quick look at

c

a

Hematitzed granite

Hematitzed episyenite

d b Older granites Younger granites Precambrian-Paleozoic

GRS = Grossschloppen U deposit

metasediments

Paleozoic Episyenites Mylonites

Uranium occurrences Faults (inferred and proven)

Fig. 41. a. Transitionof a hematized granite into a hematized porousepisyenite. HebanzDDH 11,144.2 m. b. Geological sketchmap to show theepisyenitization and structuralgeology at

themargin of granitesnear Hebanzin SE Germany (Saxo-ThuringianZone). c. Porousgraphic pegmatite convertedinto a talcized episyenite.V ěžná I pegmatite,Czech Republic. d. Porous red K feldspar pegmatite altered into an episyenite (quartz replaced by smectite?). Rozna, Czech Republic.

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Fig. 42. Tinand tungsten mine outputin comparisonto COLTANelements in theDR Congo,as an examplefor pegmatite-related rare elementproduction (database:US GeologicalSurvey,

2013).

Fig. 4b where the elements associated with scandium are plotted as a function of their geodynamic position reveals that Sc has particular af�nity to elements with mantle af �liation such as REE, Be and Nb. The presence of elements such as P and Li beingrepresentative of a different source furnish support that all of these pegmatites have gonethrough a complex and multistage process of element concentration and considered of dual-source derivation. Even if this review is devoted to the geology of pegmatites, the mineralogy of Sc has to be addressed to some degree. Scandium accommodation in the Nb–Ta oxides is favored by the euxenite-type substitution which also involves REE and yttrium, opening up a wide range of mineral s.s.s. and leading eventually to samarskite (Warner and Ewing, 1993; Wise et al., 1998). Samarskite and euxenite are both known from the sites mentioned above in Germany. Scandium is an element which goes along with Nb within the Nb –Ta couple and is more akin to the ensimatic orogens. There are several deposits in Norway and occurrences known from Madagascar (Bergstøl and Juve, 1988; Raade and Erambert, 1999; Raade et al., 2002 ). At Trutzhofmühle, Germany, a hitherto unknown Zr-Sc phosphate and silicate was found among the primary minerals (Dill et al., 2008a ). The �ndings suggest that apart from the aforementioned elements, also zirconium is concentrated simultaneously with scandium. Basic magmatic rooks area favorable host and, in places, are country rocks of Sc-bearing pegmatites.It would be a bitover-simplistic to considerthesemagmatic rocks as source rocks as well. They may rather be taken as an aid in exploration and ore guide characterizing the geodynamic setting as one with a thin crust in comparison with what is known from an ensialic orogen, where only deep-seated lineamentary faults tap the subcrustal level and provoke the ascent of � uids and melts provoking a moderate increase of element such as scandium. The pegmatite at Crystal

Mountain in Montana, USA is one of the few pegmatites which in addition to � uorite also contains euclase and thortveitite. Thortveitite-rich mine tailings can be used as a source of scandium. 4.8.4. Synopsis of Nb –Ta pegmatites

Niobium–tantalum oxides are a potential tool to contribute to the geological siting of the Nb –Ta mineralization in pegmatites but does not allow for a full blown classi �cation of the entire pegmatite which is much more complex because other rare elements are involved in the built-up of the chemical composition of the pegmatite. The growth of Nb–Ta minerals in pegmatites and in their external contact aureole is of assistance in constrainingthe mantle–crustal impact on pegmatites and its metamorphic–magmatic evolution. The use of LCT and NYF makes no sense in practice anymore, in light of the variability of columbite–tantalite s.s.s. and their relationship to the geological setting. Magmatic differentiation in pegmatites that starts off from an elevated Mn level signals some kind of preconcentration of Mn in the crustal section under consideration and characterizes a thin crust. How does these Nb –Ta oxide s.s.s. in pre-existing pegmatites respond to reactivation and the formation of pseudopegmatites? The answer to this question may be found in the publication of Černý et al. (1989) about the spodumene-bearing pegmatites at Weinebene, Austria. The content of Nb–Ta oxides is small in pseudopegmatites in the Austrian Alps. Grains of titanian ferrocolumbite described in this paper of Černý et al. (1989) are relatively homogeneous with Mn/ (Mn + Fe) 0.24–0.33, Ta/(Ta + Nb) 0.09 –0.13 (atomic ratios). It contains abundant exsolved niobian rutile and scarce inclusions of primary cassiterite. The data points plot outsidethe �eldof magmatic–metamorphic stability �eld between columbite from a true metapegmatite and

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Fig. 43. Beryllium exploited for the recovery of metallic beryllium and in colored gemstones, here emerald, in comparison to the mine output of tourmaline and precious corundum in

Madagascar, as an example for pegmatite-related rare element and colored gemstone production (database: Yager, 2012).

columbite sourcedfromthe mantle. This chemicalenvironment analysis can well be understood as the cartoon in Fig. 6a and b is viewed, which describes an ensialic–ensimatic transitional environment. The database as to reactivated pseudopegmatites is, however, not yet well endowed with data and results obtained from the test-site at the western edge of theBohemian Massif canonly contributeto theNb–Ta differentiation • •

Lanthanum (La) Cerium (Ce)

50 ppm 83 ppm

•

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13 ppm

• •

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44 ppm NA

• •

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7.7 ppm 2.2 ppm

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6.3 ppm 1.0 ppm

• •

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8.5 ppm 1.6 ppm

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Erbium (Er) Thulium (Tm)

3.6 ppm 0.5 ppm

•

Ytterbium (Yb)

3.4 ppm

•

Lutetium (Lu)

0.8 ppm

Fig. 44. Abundance of rare earth elements in the earth's crust.

in that Nb contents in columbite s.s.s. to increase near the root zone of nappes (closer to the subcrustal part) and Ta to increase away from it being enriched near the frontal or collisional parts. The abnormally high contents of Ta in the Greenbushes and Tanco pseudopegmatites support this idea and bear evidence of different processes which are able to concentrate tantalum together with another crustal marker lithium. Dismembered or rootless nappes (“klippen”) in a distal position should have been the prime targets for tantalum exploration and those pegmatite-hosted elements prone to intracrustal concentration processes. By contrast, the KoralpeLi pseudopegmatite, Austria, with little Nb-dominated columbite s.s.s. is located in a proximal position relative to its primary source or root zone. Although being chemically next of kin to Nb, Ta goes its own way driven by the geodynamic evolution. Intracrustal processes play a much stronger role for the enrichment of Ta than forNb which is sourced from lower crustal to subcrustal sources and not unexpectedly currently recovered much more from alkalinecarbonatite suites than from pegmatites. Scandium is chemically closer to trivalent Fe that can be replaced by Sc in minerals like kolbeckite, but genetically it is seeking the nearness of Nb with which it shares the same geological andgeodynamic setting. The type locality of kolbeckite is the Sadisdorf deposit in the Erzgebirge Mts., Germany. 4.9. Arsenic –bismuth– zinc –molybdenum pegmatites and pegmatite skarns

Arsenic is not high up on the agenda of exploration geologists and among those elements that attract not much attention. Bismuth is won as a byproduct from some Cu-, Pb- and Mo ores and zinc is known to be associated with lead in a wide spectrum of base metal

512


b

a

d

c

Fig. 45. a. Openpit mining operationfor kaolinizedfeldspar arkose in thelower Triassic BunterSeries at Hirschau-Schnaittenbach, Germany. Theinset is a close-upview of thekaolinized

feldspar arkosewhichis anything buta “granite wash” (seealsoinsetof Fig.45b).b. Openpitminingoperation in theresidualdeposit onthe pervasivelyweatheredTirschenreuth Granite, Germany. “Tirschenreuth Pegmatit” is a trade name for a raw material used in the chinaware industry to produce the body. It has no meaning as to the grain size of the bedrock of the residual deposit. The inset shows the “ won” material (see also inset of Fig. 45a). c. The Cornelia Mine with open pit, inclined shaft, and roof-supporting pillar, operating on the Hagendorf-South pegmatite, Germany (1982) (photograph: Rank). d. Underground operations with dump truck, shuf �e and fork in the Getrude Mine near Wendersreuth for feldspar. The feldspar deposit is located within a tabular metapegmatite. The run-off mine feldspar is delivered to the ceramic industry (photograph: Gottfried Feldspat GmbH).

deposits.Despitethis gloomy prospectas to theeconomic geology of As, Bi and Zn in pegmatites, these elements can play an important part to better understand the genesis of pegmatites and may assist to place the pegmatites within the metallogenesis of a certain crustal section. Molybdenum goes a different way, as Mo contents may come up in some pegmatites to an economic grade. In pegmatites it is mainly arsenopyrite and loellingite which play a signi�cant part among the primary minerals while scorodite is a c ommon mineral upon weathering of As-bearing primary minerals. In general, arsenopyrite in pegmatite does not contain signi�cant amounts of gold as shown by EMPA. Given that the primary As minerals evolved in a phosphate-bearing pegmatite as it is thecase in theMiesbrunn Pegmatite Aplite Swarm, Germany, the alteration product, pure scorodite is seldom and mainly phosphoscorodite, a scorodite –strengite s.s.s. develops instead (Dill et al., 2012b). Bismuthinite and native bismuth are often associated with arsenopyrite in those mineral assemblages indicative of a high-temperature hydrothermal regime. Like arsenopyrite and loellingite, primary bismuth minerals are also subjected to supergene alteration resulting in a wide range of Bi oxide-hydrates and Bi phosphates. It is won as byproduct in some sites (Section 7.9). Zinc is rarely associated in time and space with Bi and As in pegmatites. Apart from sphalerite, zinc is accommodated in zincian spinel (gahnite) and staurolite in the primary mineralization. This base metal re-appears rather late in the mineral succession incorporated into smithsonite and hemimorphite as the pegmatites undergo chemical weathering. Of particular interest for the evolution of the pegmatite, a spade of Zn phosphates warrant mentioning (Dill, 2015). They are the missing link between the Zn minerals mentioned previously, provided

the activity of HPO24 − is suf �ciently high in the pegmatite system, as at Hagendorf. The most conspicuous Zn sul�de in pegmatites is the Fe-enriched sphalerite (marmatite, christophite) which is of utmost importance for the localization of the “hot spot” within the pegmatite �eld. Abnormally high values of indium in the ZnS can also help in delineating this heat center in the pegmatite ore �eld. Numerous other elements commonly found in base metal deposits such as antimony, or lead can be analyzed or found by minerals of their own such as stibnite, or incorporated in stibiotantalite, galena and molybdenite. In the majority of cases the element contents are too small and their host minerals only randomly distributed, so that their value for a geological and geodynamic environment analysis is rather limited. Dueto the scarcity of these elements in the variouspegmatites, they are not treated by their regional distribution in some selected metallotects as done in previous sections but handled in Section 4.9 material-minded. Arsenic, bismuth, zinc and molybdenum are looked at from a chemical point of view and directly correlated with the reference types of pegmatites singled out in the preceding sections. Typical massive ore with predominantly As, Zn, Bi and Mo from pegmatitic and aplitic host rocks are shown in Fig. 28a, b, c, d, e. 4.9.1. As pegmatites (21 D)

Arsenic and its primary minerals bridge the gap between the suband supercritical part of the pegmatite system and not to a surprise areverycommon together with Sn and W minerals in greisen-type mineral associations (Fig. 28b). Among the various pegmatites under consideration in this review those pegmatites containing increased amounts of phosphate minerals


a

513

b Pegmatite Granite dikes Biotite granite Crystalline schists

Pegmatite Hyatt Pegmatite

Mica schist Hornblende schist

c

Granite Metapelites Metacarbonates Pegmatites

Fig. 46. a. Block diagram to illustrate thevarious morphologicaltypes of pegmatites in relation to thebasementrocks ofthe Appalachian Mts. (Grif �tts etal.,1953). b. Geologicalsetting in

the pegmatite �eld of the Crystal Mountains District in Colorado, USA (after Thursten, 1955). c. Geological map of the Li–Sn pegmatite ore �eld NW Kings Mountains District, North Carolina, USA (after Kesler, 1961).

and thus named phosphate pegmatites have also elevated arsenic contents.The topscorer among these phosphate pegmatites has been identi�ed at Bendada, in the Guarda District, Portugal ((Sn –Nb/Ta–Be–As–Li)– U–P pegmatite). Second in the row is the Palermo pegmatite in New Hampshire, USA ((REE–B–Bi–As–Nb/Ta–Cu–Zn–Li–U)–P). Similar to the phosphate pegmatites of the Hagendorf –Pleystein Pegmatite Province thesepegmatites pertain to the Paleozoic Variscan–Alleghanian Orogen — see also Branchville, Fair�eld Co., Connecticut, USA ((F–REE–Zn–Bi–Nb/ Ta)–Li–U–P pegmatite), Middletown, Middlesex Co., Connecticut, USA ((W–As–Bi–Cu–Mo–F–REE)–B–Nb/Ta–Li–Be–P pegmatite), Ruggles Mine, Grafton, New Hampshire, USA (REE–B–Bi–As–Nb/Ta–Cu–Zn–Li– U)–P, Schoonmaker Mine Strickland pegmatite Connecticut, USA ((Zn – REE–F–U)–Be–P–B–Li pegmatite (LiP b LiS), Dunton pegmatite, Maine, USA ((Sn–As–Nb–Ta–Li)–B–Be–U–P pegmatite (LiS–LiP)), Mount Mica, Maine, USA ((Sn–As/Zn–)Tb/Nb–U–B–Be–P pegmatite). In the supergene alteration zone the presence of (PO4)3+ and (AsO4)3+ does not cause any bother as shown inthe preface to thissection. In the primary mineralization of the pegmatite as shown in the Hagendorf area, both elements P and As are split apart from each other although forming both under reducing conditions. Phosphate forms a wide range of minerals together with bivalent Fe and Mn, in places also with Li during the initial stages of pegmatite emplacement, whereas arsenic enters the mineralogical scene in the aftermaths of phosphate precipitation under high-temperature hydrothermal conditions at the brink of the subcritical to the supercritical state (Dill, 2015). It is certainly not concentrated from a local As-enriched

hydrothermal �uid that might have been superimposed on the pegmatitelong after itsemplacement butan intrinsic element of the pegmatite mineralization. As the pegmatite is a self-suf �cient system in the area under study in the Central European Variscides, arsenic was incorporated into the felsic melt together with bismuth from gold –arsenic–bismuth mineralization embedded as stratiform layers prior to the emplacement of the pegmatite in the cordierite–sillimanite gneisses (Herzog et al., 1997; Morávek and Lehrberger, 1997). Presumably, both elements P and As were absorbed from crustal rocks during the early stages of the pegmatite'sintrusion. The process is not any different from that during reactivation into pseudopegmatites as shown by the Koralpe–Weinebene mineralization and in the pegmatites near Villach in Austria. It is dif �cult to make general statements on the behavior of As in pegmatites. The element tends to be preferably accumulated in granitic pegmatites than in pegmatites s.st. 4.9.2. Bi pegmatites (18 D)

Bismuth is frequently intergrown with primary As minerals in the high-temperature sul�de mineral assemblages in pegmatites and as shown in Section4.9.1can beaccounted forby a contaminationof thepegmatitic melt upon reaction with the countryrocks. Itsconcentration in the pegmatite is not as simple as that of arsenic in the sul �de stage. Bismutomicrolite and bismutotantalite in pegmatites reveal a going together also with elements of theNb–Ta couple, particularlytantalum.Considerable amounts of native bismuth and bismuthinite accompanying cassiterite, wolframite and even gold is known from Kigesi, SW Uganda

514


and also encountered in some of the granitic pegmatites and greisen (Gallagher, 1967) (Fig. 28a).It can be mined from pegmatites(Section7.9). 4.9.3. Zn pegmatites (16 D)

In the Arga Pegmatite Field, Northern Portugal, peraluminous pegmatoids developed as a result of anatectic mobilization of elements, containing abnormally high amounts of Be and Zn (Dias and Gomes, 2013). Silurian host rocks enriched in �uxing constituents underwent partial melting at temperatures of 650 to 710 °C and under pressure conditions in the range 2.9 to 4.2 kbar near the andalusite and sillimanite isogrades. Zinc and beryllium have some striking similarities. Both start offfrom subcrustal sources, where they occur in ratherexotic associations such as genthelvite [Zn4Be3(SiO4)3S] and willemite [Zn2(SiO4)]. These minerals were also recorded from the alkaline magmatic rocks of the Motzfeld Alkaline Complex, South Greenland (Finch, 1990). The protolith of both metals is held to be of (ultra)basic origin. On the way up of Zn- and Be-bearing solutions, the interaction with crustal rocks by, e.g., metasomatism affected beryllium much more than zinc. Genthelvite was investigated by Colombo and González del Tánago (2011) in samples from the Criollo Pegmatite, Córdoba, Argentina (Bi– Mo–Cu–F–Be–Nb/Ta–U–P pegmatite). Unlike beryllium, zinc forms only a few primary minerals of its own relevant for the formation of pegmatites. It is sphalerite and gahnite s.s.s. and to a lesser extent also zincian staurolite which re�ect an intermediate repository of zinc in crustal rocks such as metasediments (Fig. 28c). This intermediate crustal repository with non-sul�dic Zn paragenesis can almost neglected for the metamorphic rocks in and around the Hagendorf –Pleystein Pegmatite Province, in the northern Moldanubian Zone, where Fe-bearing sphalerite is present in its place. Moving further north into the frontal parts of the collision zone of the Saxo-Thuringian Zone, the granitic pegmatites are devoid of Zn mineral associations. Moving in the opposite direction into the heartland of the ensialic orogen, both non-sul�dic Zn minerals, Zn spinel and staurolite are of widespread occurrence. Zinc sul�de is concentrated near the “hot spot” in the pegmatite �eld and does not show up anywhere else in the ensialic orogen. As exempli�ed in NE Bavaria, Germany, Zn sul �de occurs in two different mineral associations, both attesting to two distinctprocesses. Sphalerite enriched in Fe, associated with pegmatitic minerals in the stock-like pegmatites mark the heat center which is also backed up by its trace element contents (indium rather high). Sphalerite in “nigrine” accompanied by uraniferous pyrochlore-group minerals and columbite(Fe) is representative of the primary subcrustal source of Zn. There are some other pegmatites in the world where such Zn minerals occur, e.g., the New England Province with the Palermo No. 1 pegmatite, North Groton, New Hampshire, USA (Kampf et al., 2012). However they have not yet been looked at from this angle and interpreted as to their geological setting. Sphalerite poor in Fe and barren as to In is not part of the pegmatite system but connected with later hydrothermal ore mineralization. 4.9.4. Mo pegmatites (11 D)

TheAltenberg Sn deposit is a pegmatite depositwhich apartfrom its main ore minerals cassiterite, wolframite also contains molybdenite (Baumann et al., 1986). There are also many Mo-bearing aplites and pegmatites mainly present as dikes in the Precambrian rocks of Scandinavia (Fig. 28d, e). The Moss molybdenite deposit, Canada, which was mined during both world wars, is hosted in late Grenvilliangranitic pegmatite dikes (Lentz and Creaser, 2005). These dikes are locally aplitic, and were intruded into the late tectonic Onslow syenite (probably correlative with the ~1090–1070 Ma Kensington suite). The Mo-rich granitic dikes at the Moss deposit are similar to other Mo-rich A-type pegmatite–aplite granitic dike systems that formed immediately after the peak of the Ottawan orogeny (1070–1090 Ma). Molybdenum stands out by another geological peculiarity; it is one of the few rare elements in the pegmatite system which shows a strong

preference to pegmatite-related skarns. The Hunt Mo skarn deposit is one of the best examples of a late tectonic, granitic pegmatite-related skarn system in the Grenville province (Lentz and Suzuki, 2000). The emplacement of the 1069 ± 11 m.y. old molybdenite with Re contents of up to 6.4 ppm Re in the proximal skarn is consistent with a contact metasomatic origin related a granitic body. It is a low-temperature, Atype intrusion, with moderate redox characteristics. In contrast to many Mo-bearing skarns in the region, this deposit has low U, Th, REE, F, and P contents (Lentz and Suzuki, 2000). The reduced marginal magnesian skarn evolved from a calc-silicate –calcite–dolomite marble. A narrow zone of endoskarn with scapolite-K feldspar-Ca clinopyroxene is found adjacent to a wider zone of an exoskarn with scapolite – Ca clinopyroxene (proximal), Ca clinopyroxene–phlogopite, Ca clinopyroxene –tremolite–phlogopite, tremolite –phlogopite (distal), marble. It hosts the bulk of the primary molybdenite (± pyrrhotite). Overall, the deposition of Mo evolved in the temperature range 650 to 500 °C according to the above authors. Other Mo-bearing skarns deposits in this region show an element association typical of A-type magmatism with U, Th and REE. Molybdenite is found frequently in aplite veins and granite aplites (Fig. 28d, e).The major source of molybdenum lies outside the “ geodynamic stability � eld” of pegmatites in the “barren zone”, to be more precise, in porphyry-type Au –Cu–Mo deposits in the Andean-type setting, which are well-represented in the modern fold belt along the West coast of both Americas. Molybdenum is a pegmatite-hosted, rift-related element (Fig. 6a, b). The crustal situation can depicted at its best by the transition between “ Rift-type” and “Andean-Type ” — see stippled line of arrowhead in Fig. 6a. 4.9.5. Chemical quali �ers in the classi �cation of pegmatites

Chemical quali �ers are applicable in the � eld and in the of �ce to classify pegmatites. For applied economic geology the number of chemical symbols can be reduced to the commodities won as a pro�t and con�ned to the value-increasing byproducts, an approach successfully taken to pegmatitic rocks in Finland ( Simonen, 1980; Lahti et al., 1989). The selection of target areas and chance of � nding blind ore bodies can be enhanced as these elements are used in context with the regional geological environment and the geodynamic setting. For genetic studies in economic geology it may be wise to add also elements like arsenic, bismuth or zinc discussed in Sections 4.9.1 through 4.9.3 to the classi �cation code, so as to see whether value-increasing or elements detrimental to the bene�ciation and processing may be expect during exploitation of these deposits. Moreover these minor elements can facilitate create a model of the pegmatite and assist in interpreting the geological environment of deposition and geodynamic setting of pegmatitization. Mineralogical quali �ers added to the structural type in curved brackets increase the value in the � eld of applied economic geology because it provides a �rst-hand information as to the method of bene�ciation used for separating the ore mineral from the gangue. In the succeeding sections the so-called “gangue” or “ trash” minerals in rare-element pegmatites are given priority and chemical quali �ers need not be used anymore. In a region wide survey, where rareelement and so-called barren pegmatites are to be expected sideby-side a homogeneous classi�cation scheme can be adopted in a way like this combining chemical and mineralogical quali �ers, Be– Li –Nb/Ta pegmatites (beryl –spodumene), Al–Na –K pegmatite (andalusite-albite-K feldspar). 4.10. Feldspar pegmatites and pegmatite skarns (41 D)

Feldspars is the most abundant group of rock-forming minerals in the earth's crust, being present in more than 60% of magmatic, metamorphic and sedimentary rocks. In combination with quartz, feldspar has been used for the classi�cation of magmatic rocks in the doubletrianglediagram(Streckeisen, 1980). In the pegmatitic rocks,in thema jority of cases only the alkaline feldspars, the potassium and the sodium


feldspars, play an important role. To be more precise, as far as the Naenriched end members are concerned, it is the albite to oligoclase of the continuous plagioclase solid solution series. Potassium-enriched feldspar occurs in different types which can be differentiated by the Si/Al disorder with microcline being perfectly ordered, orthoclase showing an intermediate state of ordering and sanidine and anorthoclase being fully disordered. O'Donoghue (2006) outlines the wide spectrum of feldspar group minerals suitable for gemological products. The hardness quali�es all of them for the group of gemstones but only a few of them end up on the jeweler's shelves or in the showroom due to their special color or optical characteristics.The current review cannot at all offer a complete overview of the feldspar pegmatites in the areas which were selected as reference for the rare-element pegmatites in the Paleozoic Variscan –Alleghanian Orogen and the Precambrian Orogens of Gondwana. On the other hand it does not make sense to try and classify the feldspar pegmatites based upon the Na- and K contents since in one pegmatite �eld the quantity of Na- and K feldspar pegmatites may signi�cantly vary among the various deposits and the more so in individual pegmatite bodies. This is shown by the composition of the various types of pegmatitic rocks in and around the Hagendorf –Pleystein Pegmatite Province, Germany (Table 10). As feldspar prevails among the rock-forming minerals in many pegmatites, the various images in Fig. 4 can be taken for references in terms of the outward appearance of feldspar pegmatites sensu lato. To illustrate the internal zonation, the reaction at the contact with the wall rocks andthe internaldeformational structures of feldsparpegmatites a series of images taken at pegmatites in Argentina, are on display in Fig. 29. 4.10.1. Feldspar granitic and syenitic pegmatites

Syenites, locally, containing feldsparin excess of 80%, granites andall the more their pegmatitic and aplitic derivates become the prime target in the search of primary feldspar deposits (Dill, 2010 — code 41a DE). The Spruce Pinepegmatite in the Micaville area, USA, is closelyassociated with alaskite bodies. Mica and amphibole gneisses with subordinate amounts of dolomitic marble form the country rocks. These rocks are intersected by dunites, alaskites and intruded by pegmatites of Early Paleozoic age. The alaskite consists of 40% oligoclase feldspar, 25% quartz, 20% microcline, and 15% muscovite and were derived from thesame parentalmagma as the alaskite (Olson, 1944; Parker, 1952; Brobst, 1962). There are several granitic and syenitic intrusive bodies elsewhere in the world grading into rock sections with a more pegmatitic structure. Some of them also show compositional changes into albitized granites and albitites, e.g. Aksoran, Kazakhstan, leucocratic granites, e.g., Takob, Tajikistan, two-mica granites, e.g., Lyangar, Uzbekistan and nepheline granites in Norway and Canada (Harben and Kužvart, 1996; Potter, 2007). 4.10.2. Feldspar pegmatoids

Plagioclase and alkaline feldspar are abundant at all stages, from the low grade to the high-grade regionally metamorphosed rocks and, together with quartz, they constitute the granular, light colored layers in gneissic rocks (Winkler, 1976). The combination of melanosome (gneissic part) and leucosome (felsic mobilizate/pegmatoid/aploid) gives a heterogeneous basement rock called “ migmatite”. Despite its abundance in gneisses, feldspar in metamorphic rock is rarely a prime target for feldspar exploitation, unless it is concentrated in metamorphic mobilizatesaccording to the CMS classi�cation scheme and termed pegmatoids and aploids, dependent upon the grain size of the sialic rock-forming minerals. There is a predominance of K-bearing feldspar in pegmatoids and aploids in and around the Hagendorf –Pleystein Pegmatite Province, Germany, in the autochthonous basement rocks of the Moldanubian Zone along the western edge of the Bohemian Massif (Table 10). Only the metapegmatites in the allochthonous parts of the MoldanubianZone, called the Zone of Erbendorf –V ohenstrauss, contain albite or Na-enriched alkaline feldspar as the only one. In the

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Münchberg Gneiss Complex, Germany, more than 30 sites were mined for soda feldspar (albite–oligoclase pegmatoids) (Bauberger, 1957). All of them have plagioclase (An8 toAn20) prevailing over quartz and muscovite. In the metamorphic mobilizates feldspar has the same anorthite content as the plagioclase s.s.s of the surrounding gneisses and amphibolites. More than 75% of the albite –oligoclase pegmatoids form layers and schlieren in metabasic rocks (banded hornblende gneisses and amphibolites, eclogite amphibolite and eclogite), the remaining part resides in ortho- and paragneisses. Feldspar in these mobilizates several meters thick is accompanied by little muscovite and quartz while minerals containing rare elements typical of many granite-related pegmatites were not spotted in these pegmatitic mobilizates. Physico-chemical investigations centered on these pegmatitic mobilizates and their metabasic country rocks (banded amphibole gneisses) were carried out by Okrusch et al. (1990, 1991) . The maximum temperature of formation was determined to be 620 ± 30 °C. Based upon the white mica that crystallized interstitially to the framework silicates of the pegmatites a temperature of formation higher than 400 °C may be inferred for the quartz–feldspar association. The structural conformity between these pegmatitic mobilizates and the enclosing country rocks suggest that pegmatitization went along with deformation of the country rocks. Liebscher et al. (2007) investigated zoisite-bearing high-pressure pegmatites in the same allochthonous unit, providing a striking example of metabasites melting under eclogite-facies conditions (Fig. 30a, b). The zoisite pegmatites are encountered in eclogites and eclogite – amphibolites. The pegmatites were derived by partial melting of a mid-ocean ridge basalt (MORB)-like eclogite at T ≥ 680 °C/2.3 GPa to 750 °C/3.1 GPa, which produced small amounts of tonalitic to trondhjemitic melt. Resorption textures indicate reheating and thermal perturbation of the whole system prior to eachsuccessivecrystallization event. Final solidi �cation of zoisite–pegmatites occurred at 0.9 ± 0.1 GPa/620 –650 °C, taking place over a depth range of 45 –60 km. For comparison, the temperature of pegmatite crystallization lies below the feldspar solvus crest (b 700 °C) but can even be lower as shown by the example from eastern Africa. The Alto Linghoa Pegmatite, Mozambique, based upon the two-feldspar geothermometry gives at a pressure of 3 kbar a temperature from 405 °C in the wall zone to 333 – 289 °C in the core zone (Neiva, 2013). It is a striking example for the temperature range across which feldspar-bearing pegmatitic rocks can form and, in my opinion,another good example againstthe idea of pegmatites to simply complete the fractionation of a granitic body stimulated by �uxing material. The entire pegmatite-forming process was probably � uid conserving: �uid present during melt formation was trapped by fully or nearly water-saturated siliceous melts, whereas �uid liberated during pegmatite crystallization interacted with dehydrated eclogite-facies assemblages to form amphibolite-facies hydrous minerals. The amphibolites constitute the host rocks of the soda pegmatoids. The pegmatoids and pseudopegmatites found within metabasic rocks or in successions of gneisses alternating with amphibolites are often rimmed by Naenriched feldspar aplites. It should be considered also in view of these petrological processes, as rocks transformed into a felsic melt, bearing Ca silicates at depth became exhumed along shear zones like those encountered in the Münchberg Gneiss Complex, Germany. The age of formation of these eclogite-hosted pegmatites lies between 370 and 380 Ma (Kreuzer et al., 1993). The Na pegmatoid at Oberkotzau, a member of the albite –oligoclase pegmatoids in the Münchberg Gneiss Complex discussed at the beginning of this section developed between 372.5 and 377.0 Ma ( Kreuzer et al., 1993). Both types of pegmatitic rocks are only two sides of the same coin, marking the incipient stages of the nappe emplacement and high-pressure regional metamorphism along the western edge of the Bohemian Massif. Both pegmatoids, the simple albite pegmatoid and the more complex zoisite-bearing modi�cation of these pegmatoids were dated. Radiometric age dating constrained the interval of the blocking temperature

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of muscovite between 325 and 425 °C. The true age of formation is assumed to be slightly higher, considering the temperatures determined for both pegmatitic rocks. The Bayan nuur and the Lun pegmatite � elds, Mongolia, 170 km west of Ulaanbaatar encompasses numerous pegmatite deposits, with the major deposits at Shagait-uul and Zakhiin-tsohio (Baljinnyam et al., 1993) (Fig. 30c, d, e). Unlike the pegmatitic mobilizates in the Münchberg Gneiss Complex, K feldspar is the major component. There is only one site in the pegmatite province where small crystals of beryl were found in the graphic pegmatites. The pegmatites are transitional between granitic metapegmatites and pegmatitic mobilizates (pegmatoids) that came into being during retrograde metamorphism, leading to unzoned pegmatitic schlieren with albite in excess of orthoclase but without any rare-element minerals of economic interest (Fig. 30f). Schmidt and Dandar (1995) studied �uid inclusions in feldspar formed during the early stages of pegmatite emplacement. They found an average temperature of homogenization of as much as 675 °C and determined the pressure of pegmatite formation to be 350 MPa. Other pegmatitic mobilizates with no obvious link to granites occur in Malawi, e.g., Mphungu mica –quartz–feldspar pegmatoid, Malawi (Fig. 30g). 4.10.3. Feldspar metapegmatites

It has already been mentioned in Section 4.10.2 and documented in Table 10 that many metapegmatites contain Na-enriched alkaline feldspar to prevail over K-enriched feldspar in the allochthonous nappes of the Moldanubian Zone. Similar to the pegmatoids related to the HP metamorphism of the Variscan Orogeny, the absolute age of formation of the metapegmatites and the relative age of their mineral associations are crucial as to the understanding of their origin and how these metapegmatites are related geodynamically and chronologically to the pegmatoids and pegmatites sensu stricto which were discussed at differentplaces in this book as to therole that they play duringthe concentration of rare elements such as Nb, Ta, Li or Be. In NE Bavaria, Germany, themetapegmatites (479 ± 5 Ma) areolder than the orthogneisses or, in other words, metagranites (404 ± 30 Ma) which was proved in the � eld by mapping and backed by radiometric age dating (Glodny et al., 1995). These felsic layers are intercalated into a series of alternating paragneisses and amphibolites, a lithological setting known from many tabular pegmatitic rocks. The metapegmatites are a separate entity with no parental granitic magma. Glodny et al. (1995, 1998) carried out some age dating in metapegmatites also straddling the Czech –German political border and crossing the lithological boundary between metapegmatites and pegmatites.The authors investigated in somemetapegmatites twopopulations of crystals, porphyroblastic mega crystals and normal crystals or matrix crystals which they treated separately as to their K/Ar age dating. The age data obtained for muscovite in various types of metapegmatites are very homogeneous as shown by the following examples: Oedental metapegmatite mega crystals 479 ± 5 Ma, Wildenreuth mega crystal 476 ± 5 Ma–normal crystal 352 ± 5 Ma, Störnstein metapegmatite mega crystal 440 ± 4 Ma –normal crystal 355 ± 3 Ma, Wendersreuth metapegmatite mega crystal 473 ± 5 Ma– normal crystal 446 ± 5 Ma, accessory monazite 480 + 7/ − 9 Ma. At Menzelhof the mega crystals aged 474 ± 5 Ma and normal crystals aged 464 ± 5 Ma yielded more or less the same age with their error bars overlapping each other. Columbite was found in this metapegmatite too and was discussed as to its Mn ∗ 100/(Mn + Fe) ratio versus the Ta ∗ 100/(Nb + Ta) ratio in Section 4.8.1 (Fig. 26). Radiometric age dating carried out by the above authors yielded an age of 475 Ma which coincides with the age obtained for the muscovite as they went through the 325–425 °C interval. Columbite from the Otov metapegmatite in the Domažlice Crystalline Complex, Czech Republic, which is geodynamically equivalent to the metapegmatites in Germany and also situated within an allochthonous complex, gave an age of 482.2 ± 13 Ma. Columbite developed late synkinematically

in the metapegmatites of these nappe complexes located on both sides of the Czech-German border during the medium pressure– high-temperature regional metamorphism (Fig. 31a). The feldspar metapegmatites are located within the klippen of the nappe, while the Hagendorf –Pleystein Pegmatite Province with its pegmatites sensu stricto are located in the window between the two klippen. While the columbite remained rather stable throughout the ensuing nappe emplacement, with no response to the varying P–T conditions the rock-forming minerals feldspar and mica got gradually adjusted to these new physical –chemical conditions reaching their � nal ad justment around 352 ± 5 Ma in the Störnstein metapegmatite. Comminution of the rock-forming micaceous minerals affected one generation of the beryl, suffering f rom brittle deformation, while another one survived totally unharmed this process or more likely to have formed in the aftermaths of the deformation (Fig. 31b). The age of formation recorded for the rock-forming minerals, e.g. muscovite, and rare minerals, e.g. beryl and columbite s.s.s, furnish clear evidence that there is a continuous transition from a muscovite – feldspar metapegmatite into a muscovite –feldspar Be –Nb/Ta metapegmatite in the klippen of the nappe with its minerals responding in quite a different way to the changes of the physical –chemical conditions. In the window of the nappe, represented by the Hagendorf –Pleystein Pegmatite Province, Be- and Nbbearing minerals are found in pegmatites s.tr. which reside in the autochthonous footwall of the nappe complex — see also Fig. 9f. It is far from being only of academic interest but also of economic signi�cance to get at least a rough idea of the intertonguing of kinematic and metamorphic processes. Differentiation of felsic constituents during the pegmatitic state might have reached an economic level but suffered a blow during subsequent metamorphism and deformation, when the differentiation of f eldspar and quartz into large mineable (mega)crystals and separate bodies of economic size was undone by the metamorphic processes superimposed on the parent material leading to a comminution of the newly formed mega crystals and rendering the pegmatitic differentiation null and void. Therefore all those metapegmatites undergoing strongstructural deformationin theaftermaths of metamorphic processesareviewed with caution when it comes to a decision whether they are worth to be operated for industrial minerals or not. Their rare metals may respond, as documented above, in a different way and the verdict handed down on the feasibility of mining industrial minerals, like feldspar, cannot be applied immediately to rare elements but has to be tested for Nb, Ta or Be during a separate trial. 4.10.4. Feldspar pegmatites and aplites sensu stricto

How pegmatites and aplites sensu stricto were emplaced has been discussed in context withthe concentration of rareelements in previous sections extensively.Excluding the simple pegmatites which are devoid of anyzonation, thezoned pegmatites enriched in feldspar often show a similarevolution as to the zonation. The matrix mineralsfeldspar are accumulated in various zones, mostly starting off at the contact with the various country rocks with a thin rim of aplite enriched in sodium feldspar andfollowed towards thecenter by a broadzoneof potassium feldspar which may surround a siliceous core — see also Fig. 36c. Where micaceous country rocks predominate among the country rocks, this grain-size differentiation of feldspar might fail to come into being and a band of muscovite formed instead (Fig. 31b).There are numerous feldspar pegmatite deposits worked in Scandinavia, Russia and along the Variscan Belt from Central through Western Europe which �t into this structural pattern. 4.10.5. Pegmatitic rocks with semiprecious feldspar varieties 4.10.5.1. Amazonite pegmatite. Some varieties of feldspar are mined for

their esthetic value only anddo not qualify as a sourceof industrial mineral for ceramic purposes or abrasives described inDill (2010).Theyare


often of smaller size as to their “ore bodies” than the large-tonnage deposits of common massive feldspar aggregates. Only a few examples of the mostwell-known speciesof semipreciousfeldspar in pegmatites are mentioned here. Their concentration is not at variance with what has been said about the various structural types of rare mineral pegmatites in previous sections. The special mineral color and luster of feldspar, however, requires further processesto make a gemstone. Processesprovidingthese chromophores for semipreciousfeldsparvarieties canoften also be related to the accumulation of rare elements in pegmatites. The green variety of microcline and intermediate stages between orthoclase and microcline designated as amazonites are used as semiprecious stones (Čech et al., 1971). Its pale bluish green (Chinese Amazonite) to deepturquoise green (Russian Amazonite) color is attributed to the presence of lead, structural water and the natural decay of potassium (Hofmeister and Rossman, 1986). It develops in pegmatites and pegmatitic mobilizates emplaced in a wide range of environments. In the pegmatites related to the Pb–Zn mineralization of the large ore deposit at Broken Hill, N.S.W., Australia, amazonite has originated by the same metamorphic processes which produced the surrounding gneisses and which were also responsible for the metamorphism of the Broken Hill ore deposit (Čech et al., 1971). Outstanding examples of amazonite are recorded from the Orlovka amazonite granite and its pegmatitic associates in Eastern Transbaikalia, Russia, which is also a large Nb–Ta deposit (Thomas et al., 2009a). The type of deposit is coded 41e D–41f D in Dill (2010). Pegmatites occur in the high-grade metamorphic rocks, called Potosi Gneiss of the Broken Hill deposit, Australia (Phillips et al., 1972). The pegmatitic rocks, which themselves were subjected to deformation, fall into the category pegmatoid and metapegmatite discussed as to their origin in Sections 4.10.2 and 4.10.3 and the rocks are consequently called amazonite pegmatoids and amazonite metapegmatites, respectively. In the Luc Yen region, Vietnam, the mineral assemblages to whom the amazonite pertains, are typical of the rare alkali metal pegmatite type (Tuyet et al., 2006). Greenish amazonite is found also in syenitic pegmatites in An Phu (Luc Yen District) and in Thach Khoan (Vinh PhuProvince) and maybe called as an amazonite syenitic pegmatite according to the discussion in Section 4.10.1. At Anjahamiary, Madagascar, in a complexly zoned pegmatite deposit giant amazonite crystals associated with lepidolite and pink elbaite were discovered in the core of the pegmatite (Pezzotta, 2001). For gemologicalpurposes or appliedeconomygeology, only, the deposit may be denominated as amazonite pegmatite; if emphasis is placed upon thegenetic part a mixedcoding Li–B pegmatite (amazonite)is recommended. One can easily conclude from the term what the pegmatite is operated for and what the chemical af �liation of the host rocks looks like. 4.10.5.2. Moonstone pegmatites. The lapidary termmoonstones describes

an optical effect that is observed in K feldspar varieties such as adularia and peristerites of the plagioclase s.s.s (see albite –oligoclase). Most moonstones from Africa, Australia and America formed in pegmatites, excluding the Mogok mining district where moonstone occurs in metamorphic rocks such as marbles (O'Donoghue, 2006). Shallow-seated, high-temperature sanidine pegmatites occur in the Black Range, Grant County, New Mexico within a rhyolite porphyry plug that has been injected into rhyolite tuffs of Tertiary age (Kelley and Branson, 1947). The pegmatites consist of quartz and sanidine with minor quantities of cleavelandite, biotite, sphene, magnetite, and ilmenite. The sanidine occurs in the moonstone variety and is believed to have crystallized at temperatures higher than those of the normal plutonic pegmatites and developed prior to the enclosing rhyolite porphyry. Even in this rather exceptional environment the CMS classi�cation can be applied as it has done for the granitic and syenitic counterparts in Section 4.10.1 and the pegmatitic deposit called a rhyolitic pegmatite (moonstone). The near-ambientshallow environment can immediately be deduced from the coding.

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4.10.5.3. Sunstone (aventurine) pegmatites. The application of the term

sunstone also known by the name aventurine feldspar has changed through times (O'Donoghue, 2006). Originallyit was restricted to colorless oligoclase with oriented inclusions of hematite and goethite but now it has been extended also to labradorite and all aventurescent plagioclase, some of which also containing Cu. Many of them are found in pegmatites but emplacement in veins has also been known. 4.10.5.4. Feldspar pegmatite-(marble-skarn). Near Itrongay, Madagascar,

orthoclase of gem-quality is exploited from calcite marble thatalsocontains considerable amounts of diopside and phlogopite and is coded 41g K in Dill (2010). In general, metacarbonates are not host of orthoclase deposits. In this particular case pegmatites, which rami�ed in these metacarbonates,are responsiblefor thisextraordinary gemstonedeposit. It is not a typical skarn deposit, although some skarn mineral such as scapolite and diopside may be observed. The coloring of these golden transparent gemstones is caused by a signi �cant amount of Fe 3+ substituting for Al3+. Servingas an examplefor the interactionof pegmatiteswithreactive metacarbonates, Itrongay has to be classi�ed as orthoclase pegmatite(marble-skarn) according to the CMSclassi�cation scheme. To highlight the difference between a more precise description of the mineralogical or chemical composition andthe hostrock–pegmatite interrelationship, thelithologyin curved brackets is linked to thetype of pegmatite with a dash — see below. Pegmatite skarns of this kind are also known from the Central European Variscides but with their minerals of only inferior quality and falling short of what might be called a semiprecious gemstone. At Wimhof near Vilshofen, SE Germany, a pegmatite came in contact with marble resulting in the precipitation of anatase, titanite, ilmenorutile, apatite, beryl, sphene, garnet, andalusite, tourmaline, and magnetite. This mixed deposit has to be classi �ed as (Ti–Fe)–B–Be–P pegmatite-(marble) according to the CMS classi�cation scheme. 4.11. Quartz pegmatites (40 D)

Quartz is ubiquitous in many pegmatitic rocks and, thus, we cannot but to mention this mineral together with rare-element pegmatites in Sections 4.1 through 4.9 and in the previous section upon dealing with feldspar pegmatites. Considering the nature of many pegmatites and the geochemical position of silica, being second most in abundance in the earth's crust behind feldspar, this ubiquitousness of quartz in this felsic rock types is not surprising. Quartz is common to many pegmatites, where it occurs in different varieties with some of them given special names owing to their color or particular crystal morphology (Rykart, 1989; Flörke et al., 1982). As this study is to outline the geology of pegmatites, all those readers who want to know more aboutthe mineralogy of quartz, are advised to consult special textbooks and journals targetingupon mineralcollectors for the specialfeaturesof thismineral. Only those varieties of quartz most widespread in pegmatites or of any commercial value are discussed in this review. The common or milky quartzis themost frequent quartzin pegmatitic rocks.Dark to blackmodi�cations are called morion or smoky quartz, while pinkish varieties are calledrose quartz(Fig. 32a).Even opal or chalcedony mayappear in pegmatites but only in zones undergoing supergene alteration (Fig. 35c). Quartz in zoned pegmatites will not create much headache or spark anydiscussion as to whether this silica concentration formedpart of the evolution of a pegmatite. Different tools and methods are available to categorize these quartz accumulations within pegmatites. Attempts have been made to get a better geological overview of pegmatite provinces in Norway. Müller (2011) used in his study the Al, Ti, Li and Ge concentrations in pegmatitic quartz from the Froland and Evje-Iveland pegmatite �elds which were formed during the Sveconorwegian orogeny (1.14–0.90 Ga) at the western margin of the Fennoscandian shield. The regional distribution of the Ti, Al, Li and Ge contents of pegmatitic quartz are used to evaluate the differentiation pattern and

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crystallization temperatures within both pegmatites �elds. By means of the Ti-in-quartz geothermometer elaborated by Wark and Watson (2006), the temperature of formation of the quartz can be determined. The same tool was also used for the internal subdivision of the quartzbearing pegmatites and aplites in the NE-Bavarian Province, SE Germany (Dill et al., 2012b, 2013, 2014a,b ). Quartz dikes striking over several hundred or kilometers at the edge of pegmatite �eldsorevenfarapartfromthemmaycausesomedif �culties as to correlate them with pegmatitic processes (Fig. 32b, c). Along the western, the southern and the north-western edge of the Hagendorf –Pleystein Pegmatite Province swarms of quartz dikes strike in NW–SE direction. They run parallel to some of the tabular aplites at the endocontact of the province but they do not extend across the boundary of the Hagendorf –Pleystein Pegmatite Province into the core zone of this cluster of pegmatites and aplites. The area occupied by the zoned pegmatites at Pleystein, Hagendorf-North and -South is devoid ofanyquartzdike(Fig. 32d).Insteadof these quartz dikesat theperiphery, at Pleystein the quartz core is exhumed in the town center (Fig. 32a). There are two different types of quartz accumulation in the region. The most conspicuous one is the quartz reef standing out from the hilly landscape resulting from the chemical weathering which has eaten away the kaolinized feldspar rim of an original quartz–Na–K feldspar pegmatite and left behind a secondary quartz pegmatite, in morphological terms a “pegmatite ruin”. On the other side we have numerous quartz dikes where feldspar has not been found either in or along the selvage of the dikes. The quartz from the core of Hagendorf-South pegmatite stock yielded a maximum temperature of formation of 557 °C, quartz from Pleystein gave a maximum temperature of 526 °C and from Hagendorf-North 499 °C. The most elevated temperature of formation of the quartz dikes was obtained from the Weissenstein quartz dikes, achieving a temperature of 708 °C. None of these quartz dikes is known to intersect any of the pegmatites or aplites thereby attesting to an emplacement subsequently to pegmatites or aplites. The “missing link” between the quartz dikes and quartz core in pegmatites is “nigrine”, a rutile-ilmenite intergrowth discussed in detail in Section 4.8.1.FortypesAandB “nigrine”, the chemical andmineralogical composition is given in Table 11a.Both “nigrine” types areenriched in niobium. Type A is disseminated in the quartz dikes of the Weissenstein swarm, whereas type B was concentrated in the roof rocks of the Hagendorf –Pleystein pegmatites dikes (Fig. 32a). The quartz dikes form part of the pegmatite system and they are considered as embryonic high-temperature quartz pegmatites which were fed from a subcrustal source prior to the emplacement of the true feldspar pegmatites — see also Nb/Ta rare metal pegmatites in Section 4.8. “Nigrine” is the “mineralogical marker fossil” and niobium the chemical one for thegenetic correlation and pinpointing the source where the �uids came from. The Hagendorf –Pleystein Pegmatite Province can be taken as an example for primary quartz pegmatites tabular, such as the Weissenstein Swarm. The latter are cogenetic with the Na–K feldspar–quartz pegmatites stocklike. Pleystein is a case-in-point for a secondary quartz pegmatite that was formed by the hypogene alteration (kaolinization) and subsequent chemical weathering and denudation of the feldspar rim. On a smaller scale, thepicturebecomes more precise as to thedistribution of quartz and feldspar –quartz pegmatites. Along a NW–SE transect from the Saxothuringian through the Moldanubian Zone – see Fig. 2 – more than 100 pegmatites have been investigated as to the quartz–feldspar composition. Along the NNW section of the transect it isaseriesofzonedfeldspar–quartzpegmatites or unzonedfeldspar pegmatites which prevail over quartz pegmatites, in the SSE section, closer to thecore of theensialic orogenquartz becomesmore dominant.This is also corroborated by the production � gures of raw material from the feldspar –quartz pegmatites. In the NNW section pegmatites were mined as a raw material for the ceramic industry and abrasives (feldspar), in the SSE section for the glass industry and for aggregates (quartz). By and large, quartz and feldspar pegmatites seem to be

randomly distributed but in essence were emplaced as a function of the geodynamic subdivision of the ensialic orogen. Silica-bearingpegmatites of gemological relevance are shown in the maps of Fig. 32e and in Table 11b. They host amethyst, smoky quartz and rock crystal, a transparent modi�cation of quartz growing into druses or miaroles and developing well-shaped crystals. 4.12. Feldspathoid pegmatites and pegmatite skarns (42 D + 43 D)

The feldspathoids are far less widespread than the feldspar group minerals with which they are structurally related (Section 4.10). Only nepheline and sodalite are more widespread among this group of minerals and, hence, deserve to be mentioned in context with pegmatites (Fig. 33a, b, c). The multifaceted group of zeolites otherwise present in many magmatic rocks and in sediments only plays a minor role in pegmatites. Scapolite is a tectosilicate s.s.s. with two end members called marialite and mejonite and found in pegmatites and in skarn deposits along their exocontact where it attracted the attention of jewelers. Feldspathoid pegmatites are found often closely related to carbonatite and alkaline complexes where the exploitation of rare elements Nb, Ta, U, Zr and Th and quarrying of ornamental an dimension stones are intertonguing with each other — see also the map in Fig. 36f. The term pegmatite becomes a more and more descriptive term for coarser-grained magmatic rocks, derived from the mantle and/or resulting from strong metasomatism. 4.12.1. Scapolite pegmatoid-(skarn)

Scapolite is stable above 460 °C at an assumed pressure of 5 kbar, a temperature well above the minimum temperature recorded for feldspar pegmatites in Section 4.10 (Kuhn et al., 2005). In Tajikistan, Li–B– F–Be pegmatites with gem-quality scapolite occur in the Kukurt antiform in the Rangkul (Kukurtskoe) district in the East Pamir Mountains (Kievlenko, 2003). The Kukurt anticline is cored by Precambrian quartzite, marble, granite–gneiss and migmatite. The gem-bearing pegmatites are relatedto leucocraticbiotite granite and two-mica graniteof the Mesozoic–Cenozoic Shatput Complex. Near the granitic pluton, the pegmatites form schlieren and vein-like bodies with topaz. Away from the pluton these pegmatite schlieren grade into microcline-beryl pegmatite and topaz pegmatite. At a greater distance from the pluton, the pegmatites form large microcline-albite pegmatites with cleavelandite, lepidolite, colored tourmaline, morganite and topaz. It goes without saying that the Li –B–F–Be pegmatites and the assumed parental granites alone cannot be held responsible for the formation of this gemstones and the interaction with the metasediments of the host anticlineis more likely to have played themostdecisive part during precipitation of scapolite in sucha superb quality. We can therefore assume that in a pegmatite cutting chlorite schist in the Minas fault at McKay Head, Nova Scotia, Canada, scapolite with interstitial analcite, also has derived from a complex interaction of the pegmatite with the adjacent country rocks (Owen and Oreenough, 1999). The McKay Head occurrence is enriched in chromium, contains interstitial rutile and hematite rather than ilmenite indicative of the pegmatitic �uids to have been oxygenated at a temperature around 400 °C. The pegmatite is interpreted to be related to highly sodic � uids derived from early Carboniferous evaporites. They are also responsible for a Carboniferous Nametasomatic event that altered a suite of alkaline granitoid intrusions (Owen and Oreenough, 1999). A tabular pegmatite was intercalated into metasediments, the body of which is in gradational contact with a schistose, biotite-rich gneissic host-rock (Mittwede, 1994). The pegmatite has a rathercalcic nature with andesine and scapolite as major components and additional minor epidote, allanite, titanite and apatite. In this case a reaction of metacarbonates (metasabkha) and a felsic melt are a plausible explanationfor the precipitation of scapolite in pegmatitic rocks — seealso Section4.7.4 “metasabkha”.Theclassi�cation as scapolite pegmatoid and scapolite pegmatoid-skarn is justi�ed for these extraordinary pegmatitic rocks.


See also scapolite in pegmatite-related molybdenum skarn in Canada — Section 4.9.4. 4.12.2. Nepheline and sodalite syenite pegmatites

Economic deposits of blue sodalite syenite were found in the Southern Bahia Alkaline Province, Brazil — see also Fig. 33b, c. This province forms part of the Achaean to Paleoproterozoic São Francisco craton (732 ± 8 Ma through 696 ± 3 Ma) ( Fig. 3). The anorogenic alkaline magmatism persisted for at least 58 Ma, demonstrating an extensional tectonicenvironmentat thistime. In the magmatic rockssodalite occurs as disseminated and interstitial crystals among alkali feldspar crystals, and is associated with calcite and cancrinite produced by the replacement of nepheline. In the metasomatic process, discontinuous bands of sodalite are in sharp contact with nepheline syenite pegmatite (Da Silva Rosa et al., 2007). Nephelinized gneisses and pegmatites act as host of corundum at Thambani, Malawi, Kishangarh, Rajasthan, India, the Wolfe nepheline belt, Ontario, Canada, and the Amazonian gneiss belt, Brazil (Appleyard, 1965; Niyogi, 1966; Lowell and Villas, 1983; Dill, 2007) — see also Fig. 36. They are very widespread in the Bancroft Area, Ontario, Canada (Reeve and Anderson, 1976; Sylvester and Anderson, 1976) (Fig. 33b,c). In Central Europe nepheline–syenite pegmatites with sodaliteand enrichments of Ditró (Ditrău), crop out in the East Carpathian Mountains nearDitró (Ditrău),Romania (Fig. 33a) (Săbău, 2009). Syenite- andnepheline syenite pegmatites of Variscan age evolved from a mildly agpaitic magma along the OsloGraben, Norway,while Caledonian representatives of this type occur on the Isle of Seiland (Bjørlykke, 1934, 1937; Andersen et al.,2010) — seealsoSection 4.3.6for Zr pegmatites. In Greenland, nepheline–zeolite–sodalite pegmatites reside within alkaline rocks (e.g. Isle of Kekertausak, Narsarsuk) (Ussing, 1912). The nepheline syenite pegmatites at Chibina Tundra (Khibiny), Russia,restwithin stronglyfractionated alkaline igneous rocks such as foyaite, nepheline syenite, chibinite, and lujavrite (Pekov, 2000; Arzamastsev et al., 2008). The pegmatites are also of interest for Zr and REE (Section 4.3). Outside the Baltic Shield at the border of the Ukrainian Shield, this holds true for the nepheline syenitepegmatite near Mariupol, Ukraine,which are alsoabundantin zircon. The presence of sodalite and nepheline in pegmatite is causative related to alkaline magmatism and desilication processes. Therefore the term nepheline or sodalite syenite pegmatites is advisable. The transition into carbonatites and alkaline igneous rocks of intrusive or effusive style is gradational. 4.12.3. Zeolite pegmatites

Zeolites are extracted from a wide range of sedimentary and magmatic deposits, mainly volcanic and volcaniclastic rocks. In pegmatitic rocks, they are neither the prime target of exploration geologists nor is this group of tectosilicates in the �rst place among mineralogists dealing with pegmatite-hostedminerals. Zeolites usedto form within the endoand the exocontact of pegmatitesTschernich(1992). There aredifferent processes which may spark zeolitization in pegmatites, in miaroles, fractures and interstices of the pegmatite-forming minerals feldspar andquartz.Xenoliths fromthecountryrocks being engulfedby the molten magma may react to precipitate zeolites and low-temperature hydrothermal �uids can enter the pegmatites to give rise to another type of zeolites. While the �rst-mentioned alteration resulted from the reaction of the melt with the surrounding rocks in the course of a contactmetasomatic process, in the second case the process of zeolitization is often dif �cult to time and genetically related to the emplacement of the pegmatitic rock. Along the western edge of the Bohemian Massif the pegmatites in the northern part of the Moldanubian zone and in the adjacent SaxoThuringian Zone differ from the pegmatites located further south in the central parts of the Moldanubian Zone with respect to the presence and absence of zeolites. In the � rst-mentioned geodynamic zones, including the Hagendorf –Pleystein Pegmatite Province, zeolites are out, whereas in the central parts of the Moldanubian Zone several

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pegmatites feature a state of zeolites-in. In the Wimhof pegmatite(skarn) sporadic natrolite has been identi�ed, in the Tittling granodiorite pegmatites veins with heulandite s.s.s., stilbite s.s.s., laumontite and stellerite evolved in the contact zone to the adjacent granite and at Kalkofen, where granites and pegmatites came in contact with marble a fracturebound mineral association with dolomite, stilbite and laumontite occurs (Lindner, 1971; Habel and Habel, 1991a,b ). At Rinchnach aplites and pegmatites reside in a granite also hosting a zeolite assemblage with chabazite, stilbite, laumontite and heulandite (Obermüller, 1989, 1990, 1992). Zeolitization accompanied the emplacement and the reaction of pegmatites at the contact with more basic country rocks, but not in its primary stage when minerals such as vesuvianite or zoisite formed. They re�ect a later stage under hydrothermal conditions at temperatures between 140 °C and 260 °C (Dill et al., 2007b). Pegmatite-skarn mineralization is much more common in the south than in the northern part of the Bohemian Massif. Zeolitization evolved in some of the pegmatites undergoing contact — metasomatism, subsequently to the reaction between a felsic melt and its more basic country rocks. Pegmatites have brought about rather uncommon zeolites together with semi-precious gemstones such as at Ambatovita, Madagascar. Chiavennite a rare Be-bearing zeolite was reported to be associated with amazonite, spodumene, Cs-bearing beryl and pezzottaite, Cs-rich muscovite –lepidolite (Laurs et al., 2003; Warin and Jacques, 2003). High-temperature zeolitization brings about pollucite at temperatures between 400 and 300 °C, and in the range 250 to 150 °C, Cs-bearing analcite and bikitaite. Natrolite, stilbite, edingtonite and laumontite crystallized at T values of less than 250 °C. While in the previous paragraph pegmatitization was described from an area intruded by magmas of the calc-alkaline clan, the exampled reported from Argentina refersto pegmatitizationin context with truealkaline intrusions. The ijolitic pegmatites of La Madera, Argentina, formed dykes running through volcanic olivine melanephelinite of Late Cretaceousage(Galliskiet al.,2004). Thedykes arecomposed mainlyof pyroxene, nepheline, devitri�ed glass and zeolites (analcite, phillipsite–Na). Nepheline is locallyreplacedby zeolites. Idiomorphicanalciteis an important hydrous phase, that is invariably replaced by phillipsite –Na. The ijolitic pegmatites were formed by H2O-undersaturated, P2O5–, CO 2– and incompatible-element-bearing melts derived by fractional crystallization of a parent olivine melanephelinite. Syenite pegmatites of the Larvik pluton, Norway, contain zeolites such as natrolite apart from many other minerals (Petersen, 1978). Zeolites although rather seldom in pegmatitesand only of interestas cesium source appear on the scene so as to be of assistance to detect contact metasomatic reactions taking place in context with the emplacement of pegmatites which used to be shown by the term “pegmatite-(skarn)” or “ syenite pegmatite”. Only those zeolites endowed with elements typical of granites and pegmatites, such as Be or Cs, can without any doubt attributed to the pegmatite system. Other members of this group of hydrous tectosilicates have to be carefully checked as to their genetic positioning. 4.13. Alumosilicate and corundum pegmatites and pegmatite skarns (49 ACD + 50 ACD)

Aluminum trioxide is among the top ten chemical compounds making up the earth crust. Despite this abundance in the earth crust, the mineral corundum, which is chemically identical with aluminum trioxide, is very rare in magmatic, metamorphic and sedimentary rocks. In pegmatitic systems the presence of corundum causes a rather paradox situation and raises the question, how such antagonistic chemical compounds suchas corundumand silica can co-existside-by-side. One mole Al2O3 and one mole SiO2 spark an immediate reaction between the two compounds resulting in one mole Al2SiO5, or in mineralogical terms results in the formation of one of the three polymorphs andalusite, sillimanite or kyanite (Fig. 34a, b, c). If FeO, MgO and H 2O are present in

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addition to the aforementioned chemical compounds staurolite will come into existence. In dehydrated systems either cordierite or sekaninaite can precipitate depending upon the availability of FeO and MgO in the chemical system (Fig. 34e, f). Three varieties of precious corundum deserve to be mentioned for their peculiar colors andthe values theymay fetch as gemstones: ruby(red),sapphire (blue),padparadscha (orange-yellow) (Fig. 34d). 4.13.1. Alumosilicate pegmatites

I cannot refrain from referring again to the often cited NW–SE transect through the western edge of the Bohemian Massif – Sections 4.6.1.2, 4.6.1.3, 4.8.1, and 4.11 – which allows for a wide range of pegmatite-related issues to be attributed to the geodynamic evolution of an ensialic orogen. All minerals looked at from a more generalperspective in the previous paragraphs occur in the various pegmatitic rocks alongthis NW–SE transect, showing characteristic trends also for the alumosilicates in pegmatitic rocks under consideration in Section 4.13.1 (Fig. 35). The pegmatoids within the klippen of the Münchberg Gneiss Complex are impoverished in rare elements and in alumosilicates. Only one kyanite eclogite pegmatoid near Falls – see also Section 4.10.2. – has been encountered in the high-grade metamorphic terrain. The Al2SiO5 polymorph found in this pegmatoid is a marker mineral for a high pressure regime. Janák et al. (2011) determined the P–T regime of these rocks in the Pirin Mountains, SW Bulgaria, part of the Rhodope UHP Metamorphic Complex, to fall in the range from ∼ 2.5 GPa and 650 °C to ∼ 3 GPa and 700 –750 °C. This indicates a moderately higher P-T regime than obtained for the zoisite eclogite pegmatoids. The kyanite eclogite pegmatoids evolved in the waning stage of the HP metamorphism and were only encountered in the allochthonous gneiss complex (Fig. 35). In the Saxo-Thuringian autochthonous complex, andalusite pegmatoids formed instead of kyanite at the Wintersberg– Katharinenberg near Wunsiedel and at Dillenberg (Tillenberg) near Waldsassen,closeto the Czech border. Both pegmatoids formed as a result of a LP metamorphism as schlieren in micaschists with garnet as an accessory mineralandno raremetal accumulation close-by. The pegmatites enriched in Be, B, Sn, U,and As atthe SSE side of Fichtelgebirge Anticline, just at the opposite side of the collision zone, are barren as to these alumosilicates. Andalusite pegmatites have been known and investigated since many decades from many sites elsewhere in the world (Webb, 1943; Rose, 1957). Temperatures of ca.650 °C arereported by Thompson and Algor (1977). These (garnet)-andalusite pegmatoids in thereference transectform thedistal facies of therare element pegmatites which mark the frontal part of the nappe system (Figs. 9, 35). The allochthonous complex of the Zone of Erbendorf –Vohenstrauss (ZEV) is well endowed with metapegmatites and pegmatoids, but neither alumosilicates nor rare metals are common to this geodynamic unit, a geological situation not at variance with what has been reported from the MünchbergGneiss Complex,the frontal equivalent to the Zone of Erbendorf –Vohenstrauss (ZEV) (Figs. 9f, 35). The pegmatoidsevolved during the waning stages of a medium-pressure regional metamorphism. At the edge of this allochthonous unit, where it got in contact with the autochthonous parts of the Moldanubian Zone, the Marchaney pegmatite formed within biotite gneisses. It is a B–P staurolite pegmatite (dumortierite–schorl). The phosphates encompass apatite, rockbridgeite, lazulite, strunzite, beraunite, vivianite, metavivianite, and santabarbaraite. The maximum stability of staurolite in the presence of quartz, muscovite, and biotite common to these rocks has been established at the following conditions: 675 ± 15 °C at 5.5 kb and 575 ± 15 °C at 2 kb (Hoschek, 1969). The elevated Al- and B-contents in thisgeodynamicallycritical shear zonefavored the precipitation of dumortierite, which can be considered as a “ boron-bearing andalusite” from the geological and chemical point of view. Both minerals are typical of this geodynamic part of the Moldanubian Zone, where

allochthonous and autochthonous units get in close touch with each other, taking into account that dumortierite re�ects the L –P part of the autochthonous and staurolite the M–P part of the allochthonous units along this thrust zone. Dumortierite has been derived from andalusite along with a K metasomatism and introduction of boron, conducive to dumortierite together with some muscovite. The pegmatites are critical markers for the marginal facies of the allochthonous complex delineated by the shear zones. They have not yet been found within the allochthonous units themselves. Andalusite,alreadyknown as the diagnosticalumosilicate in pegmatites from the Fichtelgebirge shows up again in some pegmatites in the Oberpfälzer Wald together with sillimanite (Fig. 35). The latter alumosilicate becomes dominant in the pegmatites but is still an accessory mineral and it is present at a quantity far below that of phosphates and oxides in these pegmatites. The Hagendorf –Pleystein Pegmatite Province is situated in the sillimanite zone, where sillimanite develops at temperature greater than 500 °C at any pressure and at T values greater than 625 °C at 2 kbar (Holdaway, 1971). Andalusite is present all the way down to the SE in some of the pegmatites of the Moldanubian zone. The pegmatites in the southern Oberpfälzer Wald and northern Böhmer Wald saw another alumosilicate, cordierite to form instead of sillimanite in some pegmatites (Fig. 34f). The appearance of cordierite in these pegmatites can be accounted for by the melting of pelitic and semipelitic rocks. Ellis and Obata (1992) determined the formation of cordierite in a felsic melt in the migmatites at Cooma, SE Australia under temperature conditionsof 670 °C to 730 °C anda pressure regime of 3.5 to 4.0 kbar that comes close to the environment of formation of the migmatites displayed in Fig. 34f. More common to pegmatites, the Fe-enriched varietyof cordierite,sekaninaite was described from several localities after its �rst discovery in the Dolní Bory pegmatite, Czech Republic (Černý et al., 1997) (Fig. 34e). Gottesmann and Förster (2004) who investigated sekaninaite from the Satzung Granite, Germany, concluded that sekaninaite together with hercynite, quartz, and brown biotite was assimilated from the metamorphic basement by a chemically evolved granite magma. The presence of accessory alumosilicates such as cordierite s.s.s, and sillimanite in pegmatites need to be tested by petrographic studies in thin sections for each case as to be a part of the pegmatite assimilated from the country rocks or whether it has newly formed in the course of mobilization of aplites and pegmatites. A quick look at the distribution of alumosilicates in pegmatitic rocks alongstrikeoftheNW–SE transect through theCentral Variscides reveals a trendwhich well accords with the change in the metamorphic facies in the region under consideration (Dallmeyer et al., 1995). The peraluminous marginal facies of rare metal pegmatites and the peraluminous aplitic and pegmatitic rocks at the rim of larger pegmatite provinces are the result of metamorphic and anatectic mobilization. It goes along with the lithological –geodynamic evolution of a crustal slap, signaling that at least the initial stages or marginal facies of the Central European pegmatites sensu lato went through a metamorphic-anatectic stage. In consequence of that conclusion, the incipient stages of pegmatites irrespective of their major element composition are controlled by the geodynamic evolution of the ensialic orogen during the Paleozoic. All metamorphic rocks creating these alumosilicates in pegmatitic mobilizates require parent rocks of suf �cientlyhighaluminumcontents or must undergo some desili�cation in the course of metasomatic processes to achieve equal molar proportions of Al 2O3 and SiO2 to form the sillimanite-group minerals or their Fe- and Mg-bearing analogues. High-temperature metamorphic systems ful�lling these chemical requirements are the most favorable candidates to give rise to pegmatite. Thesealumosilicates may locally, where shear zones favor the introduction of boron or �uorine accommodate these “pegmatitophile ” elementsinto their structure andconvertintodumortierite (e.g. pegmatite at Marchaney) and/or topaz (e.g. pegmatite at Lam Schwarzeneck), respectively. For the sake of completeness, the extraordinary hightemperature pegmatoids bearingcorundum, prismatine and tourmaline


have to be mentioned from the Waldheim granulite, Germany (Schreyer et al., 1975). How they sweep their way through these lithologies and eventually end up in a rare metal pegmatite province is dictated by a wide range of physical –chemical processes that were discussed in Sections 4.1 through 4.9 for the various element sets. Granitic pegmatites, such as those in the western extension of the Moldanubian Zone, in the Schwarzwald (Triberg, Germany — (Sn –U–As)–B–Be granite pegmatite) and Vosges Mts. (Rothau, France — (Sn–P)–B–Be granite pegmatite) lack this special facies. In some places contact-metamorphic rocks such as hornfels with porphyroblasts of andalusite (chiastolite) form around granites and their granitic pegmatites. The contacts are sharp andthe contact-metamorphic zonation is well de�ned.Thesestructures and textures of andalusite-bearing hornfels contrast with the initial stages of pegmatites characterized by alumosilicate pegmatites whose contacts are gradational and the ensuing rocks are granular massive rather than spotted. The question whether these alumosilicate pegmatites show up in reactivated sections of an Alpine-type orogen as pseudopegmatites cannot be answered de�nitely as to their genetic position in this study. In St. Radegund and some pegmatites of the Angerkristallin, Austria, kyanite and staurolite appeared in rare metal-bearing pegmatoids, metapegmatites and pseudopegmatites. Esterlus (1983) assumed that the presence of staurolite resulted from a medium-grade overprinting of the spodumene pegmatites during the Alpine orogeny which he held to be Cretaceous in age in this study site in Austria. There are many places where sillimanite-group minerals are accumulated to economic grade in metamorphic rocks. The most-wellknown deposits of this kind were discussed in Dill (2010) as metamorphic deposits,what is certainly true andcoded49c IJ.But notall of them are metamorphicin the strict sense and obviously owe their up-grading to an economic size, particularly in case of the so-called sillimanite, kyanite or andalusite “ quartzites”, by mobilization processes. Terms like andalusite quartzite would imply something like a “ clay-sandstone ”, hard to believe from the sedimentological point of view. In view of the quartz pegmatites/pegmatoids – Section 4.11 – it is more in accordance with the geological setting to invoke to a sillimanite –quartz pegmatoid rather than a quartzite. Although not of commercial interest,the NE Bavarian Basement offers some sites where these rocks crop out and can be taken as useful marker minerals to constrain the physical–chemical regimeof the host pegmatites.This idea is strongly supported by theinvestigations cited below. Shear zone-hosted or quartz-vein hosted kyanite mineralizations are reported from various sites inter alia by Allaz et al. (2005) fromthe Simano nappe (CentralAlps).Physicochemical investigations showed that these veins are closely related to the regional metamorphism and not part of an independent fracturing processes (630 ± 20 °C and 8.5 ± 1 kbar) ( Fig. 34c). 4.13.2. Corundum pegmatites

In the previous Section 4.12 on feldspathoids, the focus has been moved from the pegmatites, proper, to the surrounding country rocks, while noting the signi�cance of basic rocks as the most reactive ones in the crystalline basement. This applies all the more so for the ultimate stage of Al concentration in pegmatites,accumulating corundum, which was found in the endo- and exocontact of pegmatites in the central parts of the Moldanubian Zone of the Böhmer Wald (Fig. 35). Corundum, often present in its blue, translucent variety and called sapphire, is found in gneisses together with andalusite, and in pegmatites together with vesuvianite and titanite in contact with marble and calcsilicate rocks (e.g. Wimhof, Germany). A remarkable difference has to be noted between the pegmatites bearing alumosilicates in the NW and SE part of the Moldanubian Massif. In the SE, called Böhmer Wald, these peraluminous pegmatites with andalusite, corundum and cordierite are also enriched in rare metals and as such justify a mixed classi �cation according to the CMS classi �cation scheme in a way like that: P –F–B corundum–andalusite –garnet pegmatite-(marble) at

521

Schwarzeck, REE–Nb–P–B corundum–garnet–andalusite –cordierite pegmatite-(gneiss) at Blötz, Nb–P garnet-andalusite pegmatite(gneiss–mylonite) at Drachselrieth, B –Be–P vesuvianite-andalusite– cordierite –garnet pegmatite-(gneiss). There are only a few pegmatites which stand outas pure rare metal pegmatites such as theHühnerkobel pegmatite stock which resembles the Li-free Hagendorf pegmatites ((Sn–As–F–U)–Be–Nb–P pegmatite (stocklike)-(granite–gneiss)) the Reitenberg–Kaitersberg pegmatite (U–B pegmatite-(gneiss)) and the Schöllnach pegmatite (Sc–Li–F–B)–REE–Be–P pegmatite (tabular)(granodiorite-granite). The unusual occurrence of corundum in siliceous rock, like pegmatites, can hardly be explained by a normal fractionation of a siliceous melt. Andalusite- and corundumbearing pegmatites in the Yosemite National Park, California, USA, which have only scienti �c relevance are considered as true magmatic by Rose (1957) and were attributed by him to the Cretaceous Sentinel gr anodiorite. Desili�cation resulted in these rocks from reaction with the adjacent hornfels. It has been interpreted in terms of a subsolidus potassium metasomatism of andalusite to muscovite which leads to a local de�ciency in silica in the �uids (Rose, 1957). The overall reaction can be presented as follows: 6 andalusite + 2K + 3H 2O 2 muscovite + 2 corundum + 2H +. Mineral assemblages like that can also be met in the Mazán Pegmatitic Field, Northwestern Argentina (Sardi et al., 2009). Corundum-bearing pegmatitic rocks are rarely corundum-only deposits and often associated with alumosilicates as shown in the Moldanubian Zone of the Böhmer Wald and also many sites elsewhere in the world, some of which are discussed here for their origin and to constrain the physical–chemical regime of formation. Oneof the strikingexamples is the plumasite pegmatite at Mangare, Kenya, a tourmaline–ruby mineralization related to kyanite pegmatites (plumasite: coarse-grained rock consisting of anhedral corundum crystals in an oligoclase matrix) (Mercier et al., 1999). Plumasite, a corundum-bearing plagioclasite widespread along the Mozambique Belt in eastern Africa resulted from the desilication of pegmatites by ultrama�c rocks (Pohl and Horkel, 1980). Its origin lies in the � eld of migmatization and metamorphic remobilization. Another typical corundum-bearing pegmatite occurs at Dac Lac in southern Vietnam (Fig.34d). Theanswer to thequestion on theemplacement of plumasite and their associated corundum deposits can more easily be given when taking into consideration studies by Frost and Beard (2007). Metaultrabasic rocks have the lowest silica activity of common crustal rocks. The interaction of these � uids with adjacent rocks produced rodingites, and the low silica activity also explains the occurrence of low-silica minerals such as hydrogrossular, andradite, jadeite, diaspore, andcorundum within or in rocks adjacent to serpentinites. Sapphires in the Andranondambo region, Madagascar, are bound to a granulite series consisting of marble, gneiss and pyroxenite where sapphires preferably formedin thin veins in the reaction zones between pegmatite dikesand pyroxenite (Schwarz et al., 1996). At the John Saul ruby mine, Kenya, rubies are recovered from pegmatitic mobilizates in ultrama �c rocks and in the Rockland ruby Mine, Mangare area (SE part of Tsavo National Park), Kenya, productive pegmatites line the boundary of ultrama �c rocks, plagioclasites and desilici �ed gneisses. The ruby-bearing rocks crystallized under granulite-facies conditions (Mercier et al., 1999). At Umba River, NE Tanzania, sapphire- and ruby-bearing pegmatites cross-cut ultrabasics but not the surrounding country rocks (Solesbury, 1967). Ruby from veins intersecting amphibolite and anorthosite provide P–T estimates of 750–850 °C and 9 –11.5 kbar (Mercier et al., 1999). It is widely known that precious corundum deposits, mainly bearing ruby, the red variety of corundum, are linked to metacarbonates, skarns and calcsilicates. In some cases granites and pegmatites nearby suggest the presence of a ruby pegmatite-(skarn) in other sites the genesis is still a matter of conjecture, covering the wide spectrum from regional metamorphism to metasomatism. The Jegdalek ruby deposit with significant quantities of spinel, Afghanistan is emplaced in skarns. Proterozoic ⇒

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(1.5–1.97 Ma) dolomitic and calcitic marbles are intruded by leucocratic granites and their aplitic and pegmatitic derivatives (Kievlenko, 2003). The mineralized collisional zone of corundum extents into Tajikistan, Pakistan (Hunza) and Kashmir (Azad). Pegmatitic processes are evident in some deposits in Sri Lanka. Metasomatic hydrothermal processes have been invoked for some of the deposits in Sri Lanka as demonstrated for the Bakamuna deposit in the central granulite belt (Fernando et al., 2005). Corundum and spinel were encountered together with taaffeite and scheelite, all of which were precipitated from Be- and W enriched �uids in the temperature range from 200 °C to 400 °C at a mid-crustal level. The Bakamuna corundum-skarn, Sri Lanka, developed as a result of a pegmatitic intrusion leading to metasomatic desilication of syenite veins with subsequent transformation to corundum–scapolite rocks (Silva and Siriwardena, 1988). At the very end, spinel is assumed to have replaced corundum. Further examples of pegmatite interference on the deposition of precious corundum in such a transitional setting are mentioned in Dill (2010). Gem-quality sapphirein Canadais recordedfrom syenitepegmatites of the Haliburton –Bancroft alkaline complex. The pendant to the Haliburton–Bancroft alkaline complex is the Ilmeny Gory in the Chelyabinsk Oblast', Urals Region, Russia (Popov, and Popova, 2006). The sapphire deposit Dusi (Garba Tula), Central Kenya, is unique as it is hosted by a more Ca-enriched intrusive rock of monzonitic composition (Simonet et al., 2004). Desilici�ed pegmatitic mobilizates play an important part as host and as desili�cating agent during concentration of corundum. Corundum is a constituent of diorite-plumasite pegmatites or found together with margarite in marundites. In Madagascar, thecirculation of �uids along discontinuities allowed in-situ alkaline metasomatism, forming corundum host rocks related to desilici �ed granites, biotitites, and some peculiar rocks such as sakenites and corundumites (Rakotondrazafy et al., 2008). Different ideas have been put forward to explain the origin of these deposits. When silica-bearing pegmatites intruded rocks undersaturated with silica, the silica is extracted or exchanged from the pegmatite and reacts with the undersaturated host rocks producing new minerals that contain silica. Pegmatites may have been desilici�ed by their �uids interacting with silicaundersaturated country rocks, e.g., ultrama�c country rocks. Depletion in silica content that favors corundum formation may also be achieved by interaction of ma�c or ultrama�c rocks with metapelites or by partial melting of the pelitic country rocks. At Mahenge, Tanzania, rubies are found in pegmatites bearing green tourmaline as well as in marbles (Hauzenberger et al., 2005). Thrust of felsic rocks against ultrama�c rocks may create reaction zones leading to similar desilici�cation. In plumasite and marundite, sapphires, rubies, showcase-quality or industrial grade corundum may come into existence. At Barauta, Zimbabwe, in Kashmir, India and in Moneragala and Okkampiitya, Sri Lanka, sapphire is encountered within pegmatites (Hughes, 1990). Shear zones and lineamentary fault zones are instrumental as it comes to juxtapose such contrasting rocks like pegmatites and ultrabasic/carbonate rocks so that desili�cation can take effect and chromophores to make a precious corundum are made available. 4.14. Garnet pegmatites and pegmatite skarn (47 D)

The general formula of garnet s.s.s. may be expressedas X3Y 2(SiO4)3 wheretheXsitemaybeoccupiedbybivalentFe,Ca,MnorMgandtheY sites bycationsof thetrivalentand tetravalentelements Fe,Al, Cr,Zr and Ti. The latter ensue a charge balance in the anion complex which in nature is dominated by Si. Garnet group minerals have a large stability �eld and were mainly found in the metamorphic realm, hosted by paragneisses and micaschists derived from pelitic rocks. In contact with metasomatic and contact metamorphic rocks garnets used to be enriched in Fe and Ca, in the nearby pegmatites they are less common and characterized by increased amounts of Mn. Spessartite-enriched garnet with a signi�cant component of almandine has been recorded from many granite pegmatites and aplites, as

exempli�ed among others by the Hagendorf –Pleystein pegmatite province, Germany and the Ljosland Pegmatite, Norway (Fig. 36a, b, c). The Laghman pegmatites, a Be –Li-pegmatites in Nuristan, Afghanistan, may serve as an example where Mn-enriched garnet from pegmatites even attains gem-quality. The host pegmatite contains Li-tourmalines, pink and blue beryl, spodumene (including kunzite) and spessartite (Bariand and Poullen, 1978). Spessartite-enriched garnet is concentrated in Na–Li pegmatites, in marginal, aplitic and quartz –muscovite zones, in albitized zones and even in the quartz core of some pegmatites. Garnets are encountered in simple as well as complex pegmatites with garnet composition strongly varying with the type of pegmatite (Kievlenko, 2003). Decreasing pressure and temperature of formation result in decreasing pyrope and almandine components and increasing spessartite content.Garnet in muscovite pegmatites is composedgenerally of almandine (57–75%), spessartite (14–26%) and pyrope (4–12%). Garnet compositions in REE–Be–muscovite pegmatites typically have a different composition with almandine (34 –54%), pyrope (0.5 –1.6%) and spessartite (43–54%). In REE–Na–Li pegmatites, the garnets have compositions in the range of spessartite (78–90%), almandine (5–17%) and pyrope (up to 3%) (Kievlenko, 2003). The garnets in pegmatites rarely attain gem quality, butoften are categorized as showcasegarnets. As spessartite-enriched garnet s.s.s. have proved to preserve their crystal habit best among all garnets even in alluvial –�uvial placer deposits, theymaybeusedasapath�nder to different typesof rare metal pegmatites (Dill et al., 2007a). For the pure spessartite composition the lower reaction limit at pressures between 200 and 1500 atm is at 410 °C. For spessartite-almandine mixed crystals the limit rose with increasing almandine content from 410 °C (spess90alm10) to 500 °C (spess 50alm10) (Matthes,1961). Kievlenko (2003) reports gem garnets to have been recovered from pegmatite deposits from Brazil, Madagascar, Myanmar and Sri Lanka. Roache et al. (2005) studied the synchronous deformation and metamorphism at the Cannington Ag–Pb–Zn deposit, in northeastern Australia, which involved a Ca and Mn mobilization that accounts for the distribution of pyroxene- and garnet-bearing metapegmatites. The Proterozoic upper-amphibolite-facies quartzofeldspathic migmatitic gneiss, and lesser amphibolite are also host to pegmatites. Peakmetamorphic migmatitic gneiss and anatectic pegmatite have ages between 1.6 and 1.58Ga (Giles and Nutman, 2002). The assemblage of deformation D 1 includes besides garnet migmatitic gneiss also garnet metapegmatites. High concentrations of Mn in D 1-related garnet (12 mol% spessartite) have been derived from the surrounding gneiss andconcentrated at contacts with amphibolite as a result of metasomatisminthewakeofpartialmeltingduringmigmatizationandtheformation of the pegmatitic rocks. Thrust shear-zone formation during D 1 was held responsible for the Mn-rich �uids surrounding the Core Amphibolite, as observed in the concentration of Mn-enriched garnet. Moretz et al. (2013) investigated the composition of garnet as an indicator of rare metal (Li) mineralization in pegmatites. Their statement that Li-poor, NYF pegmatites have garnet with the lowest Mn and highest Fe contents, whereas garnet in Li-rich, LCT pegmatites has the highest Mn and lowest Fe contents cannot be proven by detailed analyses in the pegmatite provinces at the western edge of the Bohemian Massif. In this case, Hagendorf-South and Pleystein should have the most elevated contents of spessartite-enriched garnet. They do not have any, while Miesbrunn and Trutzhofmühle, devoid of Li have the highest spessartite-contents in their garnets. Pegmatite-related garnet is specialized in spessartite, but per se no marker for abnormally high lithium contents in the host pegmatites as numerous examples reveal. Garnet from the Bayerischer Wald with a composition in the range Spess57 through Spess67 is unrelated to any lithium concentration (Schaaf et al., 2008). By contrast the most elevated Li concentration at Hagendorf is not correlated with Mn-dominatedgarnet. Manganiferous garnetmay be indicative of higher temperatures in thestudy area, but it cannot be used as a stand-alone marker but has to be coupled with Mnbearing apatite in the marginal zone looked at vis-à-vis minerals like


biotite. There is more than onemineral in thepegmatite system striving for accommodating Mn in its structure and therefore competitive minerals have scrutinized carefully. Spessartite-bearing almandine s.s.s. coupled with the above phosphates and silicates is used as a marker to assess the depth of formation or they might be used to predict the presence of Mn-bearing phosphates in a pegmatite province.

523

Considering the muscovites pegmatites and their host rocks reveal, that prospective deposits of mica pegmatites, with sizeable pods and pockets within feldspar and quartz bodies, used to be intercalated into mica schists or mica gneisses and encountered in granites. Phlogopiteenriched types have been derived from melts of subcrustal origin (Fig. 6c). Biotite-enriched types of pegmatite are shown in Fig. 37g. 4.16. Graphite pegmatites and pegmatite skarns (52 D)

4.15. Mica pegmatites and pegmatite skarn (59 D)

Muscovite is the most common phyllosilicate in many pegmatites, metapegmatites and pegmatoids and thus, has been mentioned in many sections of this book. In some pegmatites the booklets of muscovite are enriched to a considerable amount and they attain a size that renders mica to be won as a by-product together with feldspar and quartz mining (Fig. 37a, b). Ihlen et al. (2002) came most closely to the ideas of the CMS classi�cation scheme as they subdivided the syn-orogenic pegmatites in Norway according to their major minerals. In addition to plagioclasedominant pegmatites and K-feldspar-dominant pegmatites they singled out a third class, called white mica pegmatites. The mica is said to characterize the degree of fractionation of the pegmatitic melt. RichterBernburg (1950) conducted a subdivision of mica pegmatites in Norway, from stock-like pegmatites (e.g. Kragerö) related to a small pluton at depth through steeply dipping tabular (e.g. Holene) or subhorizontal sill-like pegmatites (e.g. Hitterö) extending for kilometers (Fig. 37c, d, e). Based upon his mapping, Richter-Bernburg (1950) demonstrated thatthere is a gradualtransition fromtabularpure quartz pegmatites or dikes (seeSection 4.11), through quartz–feldsparpegmatites (Section 4.10) devoid of mica to pegmatites strongly enriched in muscovite and biotite while getting more and more impoverished in quartz. The author could not �nd any close link between the schistosity and deformation of the metamorphic country rocks and the siting or size of the mica pegmatites. Dyke swarms of mica pegmatite also occur in the Uluguru Mts., Tanzania, where these strongly tectonized tabular pegmatites intersect gneisses. As a byproduct they may, locally, also contain uraninite, beryl and tourmaline and as such classi �ed as (U–Be–B)–mica pegmatites (Sampson, 1962). Phlogopite-bearing pegmatoids mined at Ambatoabo, Madagascar, formed in an environment completely different from what has been reported for the Norwegian mica pegmatites (Ackermand et al., 1989). In Precambrianmedium-and high-grade paragneisses arrangedin N–Sdirection parallel to the trend of the Mozambique Fold Belt of eastern Africa, diopsidites are intercalated into the gneisses as conformable layers up to several meters thick. They contain pegmatoids with diopside, scapolite and phlogopite attaining a size of over one meter in length. The metamorphic rocks of the Betroka–Beraketa Belt formed at temperatures exceeding 850 °C and at a pressure of between 7 and 8 kbar. These phlogopite deposits are genetically related to the aforementioned Pan-African Th–U skarn and orthoclase deposits at Itrongay, Madagascar, which also contain phlogopite concentrations. At Kapirikamodzi Hill, Malawi glimmerites within amphibolitefacies metamorphic rocks have been mapped (Fig. 37f). The vermiculite-enriched core was intruded by quartz–feldspar pegmatites that contain among others vermiculitized phlogopite. It is a complex rock, covering the full range from siliceous quartz pegmatites, through quartz–feldspar pegmatites to nepheline pegmatites (Dill, 2007). The original carbonatite was altered to pyroxenites and glimmerites and last but not least ended up in a vermiculite mineralization with various types of pegmatites re�ecting a strong desilici�cation (Morel, 1988). It is an example for the close genetic association between carbonatites and some pegmatites. As the geological scenario resembles to some degree what has been described from Madagascar, the origin of both type localities abundant in phlogopite seems to be similar. In Malawi, a late stage hydrothermal activity gave rise to vermiculite and paved the way into the carbonatite suite at Palabora, South Africa.

Unlike its “ brother” diamond which stands at the top of the Mohs hardnessscale, �akesofgraphiteare�exible,exhibitperfect basal cleavage parallel to {0001} and themineral ranks very low in the Mohs hardness scale (1–2). While diamond is totally absent from the mostly lowpressure–high temperature regime of many pegmatites, graphite is a rareconstituentin pegmatite butneverthelessmayattainin somecountries ore-grade in pegmatitic rocks. The widely discussed model of graphite to have been derived from peat via coal passing through different coali�cation stages cannot be applied in this metamorphomagmatic setting where the pegmatitic rocks were emplaced. True graphite forms at temperatures greater than 400 °C (Landis, 1971). Different ideas that may also be applied to pegmatitic rocks have been put forward. Epigenetic graphite � lling veins intersecting pegmatites may have originated from lateral secretion and lead to their denomination as graphite pegmatites (Erdosh, 1972). Carbon may be released from pre-existing carbonate minerals by direct methanation through reaction with elemental hydrogen (Salotti et al., 1971). Boudouard reaction proceeds at 600 to 750 °C and falls into the temperature range in which the emplacement of pegmatitic rocks may start forming 2 CO

⇒

C + CO2.

Graphite occurs in alkaline pegmatites at Hackman Valley, Mt. Yukspor and Chibina Massif, Russia. It is associated with minerals including aegirite, apatite, albite, nepheline and natrolite ( Jaszczak et al., 2007). Graphite-bearing pegmatitic dikes with abundant CO 2-rich inclusions occur side-by-side with wollastonite-bearing calcsilicates and gneiss–charnockite horizons in the supracrustal terrain of the Kerala Khondalite Beltattesting to the transfer of carbonic �uids through magmatic conduits (Satish-Kumar and Santosh, 1998). A second type of graphite which was found in Mongolia may be brought in the reaches of pegmatitization during an early stage of magmatic activity and supposedto be transitional into a skarn-type graphite mineralization. The mineralization is akin to mineralizations described from the Botogol deposit in eastern Russia (Fogg and Boyle, 1987), where the graphite formed as early as the syenite. Only in the graphite syenite pegmatites a deep subcrustal source is evident. In many other pegmatite bodies with graphite such as in Quebec, Canada, their origin is dubious. Referring again to the quartz pegmatites, discussed in Section 4.11, solid hydrocarbons concentratedalong fracturesin quartz dikes andfrequently associated with uranium black ore minerals such as along the western edge of the Bohemian Massif at Wäldel, Germany, and at Dylen, Czech Republic, gain importance as to the origin of graphite in pegmatites (Dill, 1983a, 1983b). There are many different categories of native allochthonous bituminous substances found as vein deposits and de�ned as mineral wax (ozocerite), asphaltite (gilsonite, glance pitch, grahamite), and asphaltitic pyrobitumen (wurtzilite, albertite, impsonite) ( Jacob, 1993). The solid bitumen with the most elevated re�ectance is called impsonite (Levine, 1987; Levine et al.,1991). Cataimpsonite is shown to gradually pass into semi-graphite and eventually into graphite. Unless bituminous matter is found in the basement rocks around graphitedeposits the source of graphitein quartz–feldspar pegmatites sensu lato is likely to have been at a subcrustal level. This is strikingly demonstrated by the paper of Silva (1987). The vein-type graphite mineralization in the Bulathkohupitiya area with the main deposit at Bogala, Sri Lanka occurs in the zones of deep-seated fractures in

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supracrustal stratiform metasedimentary rocks resulting from the differential rise of subcrustal migmatites (Silva, 1987). Several veins of graphite intersect the syenite pegmatite (Fig. 37). Mineralogical and geochemical study of the wall rocks reveals a well-zoned alteration halo about the deposit. Chemical zoning in the altered wall rock and the relict mineral replacement textures indicate deep-seated hydrothermal activity. 4.17. Kaolin in pegmatites (55 DH)

It is widely known, kaolin is a rock with kaolinite-group minerals prevailing over mica-group phyllosilicates, quartz and feldspar. The kaolinite-group minerals can involve kaolinite, dickite, nacrite with different degrees of Si/Al disorder and halloysite, present also in its metaforms. Quartz and feldspar and, to some extentmica, are relic minerals of hypogene and supergene alteration processes (Dill et al., 1997, 2014b, 2015). Considering the effect of both types of alteration in granites and pegmatites, in principle no difference may be recognized as far as the conversion of minerals is concerned. In Cornwall, Great Britain, and in the granite-relatedkaolin deposits in Germany, there are pegmatitic granites or pegmatitic pockets within the parental granite that do not behave any different as to the kaolinization as the overall homogeneous or equigranular granite. There are, however, signi �cant differences as to the morphology and size of the resultant kaolin deposits. These features are highlighted by a comparison of kaolinization affecting the Late Variscan granite near Tirschenreuth, currently mined as a ceramic raw material and a late Variscan pegmatite, the often quoted Kreuzberg Pegmatite in the town of Pleystein,which has never attracted the interest of mining engineers as a kaolin deposit, as the kaolin in the area was washed away almost completely as the drainage system incised in its gneissic bedrocks, including the Kreuzberg Pegmatite. During the waning stages of the Variscan Orogeny, two-mica granites were intruded near Tirschenreuth being part of the larger Falkenberg Granite Massif. They were uplifted after the Variscan orogeny when the entire basement was subjected to intensive chemical weathering and erosion. This early stage is no longer to be recognized. Another period of chemical weathering took place during the Cretaceous and the Cenozoic, when a vast peneplain truncated both the metamorphic country rocks and the granitic intrusions. Only the youngest relics of this chemical weathering have been preservedfromerosion in somedepressions,forming today disconnected blankets of kaolin with an unduluous basal contact on top of the granite. They were subjected to a more precise dating and geomorphological investigation, using U/Pb isotope ratios of secondary U minerals and K/Ar isotope data of cryptomelane as a geological clock to constrainthe supergene alteration (Dill et al., 2010a,b). The age estimates obtained from these secondary U and Mn minerals for the immediate surroundings of the Tirschenreuth kaolin deposit range between 4.55 Ma and 3.99 Ma. Only Strobel (1969) claimed that a hydrothermal kaolinization was operative at somepoints and alsoaffected the granitic parent rocks. All other students, such as Köster (1974), Kitagawa and Köster (1991)backed the idea of a supergenenatureof the kaolinization which was most ef �cientunder the tropical to subtropical paleoclimate during the waning stages of the Neogene in this Central European region. In the Hagendorf area the chemical weathering was datedby means of the K/Ar method applied to cryptomelane at 4.20 ± 0.33 Ma which falls into the same age interval as mentioned above for the granite (Dill et al., 2010b). In the stock-like pegmatite of Hagendorf-South and Hagendorf-North the degree of kaolinization is weak and in the tabular pegmatites almost absent. Although, the concentration of feldspar in the pegmatite is more massive than in any of the surrounding granites the supergene impact on this vulnerable tectosilicate was low, due to the comparatively small size of the surface exposed to weathering at outcrop in both structural types of pegmatites. On the other hand the question has to be raised, why

the same quartz–feldspar stock at Pleystein was deprived of almost all of its feldspar and stands out today as a quartz pegmatite reef, but its neighbor Hagendorf-South, almost of the same size, did not suffer from such an alteration. Prior to the post-pegmatitic weathering and erosion which affected this pegmatite stock like its neighbors, there was an intensive hydrothermal kaolinization at depth eating away the massive Na–K feldspar rim overlying the quartz core at Pleystein. It converted the stockworklike aplite veins in thehangingwallbiotite–gneissesinto kaolinite–feldspar–quartz aplite veins and the aplite underneath the quartz core into a kaolinite–quartz aplite to kaolinite aplite tabular. This is also valid for the feldspar rim which was completely argillized. The ascending hydrothermal �uids were impounded by the sealing quartzcore and did their job of alteration to full capacity, so that all degrees of hypogene kaolinization may be observed in the exocontact of the quartz core, excluding the topmost parts. When the kaolin–quartz pegmatite stock was uplifted, its gneissicroofrockwas gradually destroyed by the �uvial drainage system. Presumably, during the initial stages a sortof collapsebreccia consisting of gneiss fragments supported by a soft kaolin matrix came into existence. Upon further incision of the river the friable material was denudated to completeness and left behind the quartz core, standing out today from the landscape as a quartz reef (Fig. 32a). Only those parts of the kaolinized rim were preserved from erosion, that were protected by the intact gneissic roof rocks or by the sheltering effect of the �at-lying quartz core. Quartz reefs or quartz pegmatite ruins have to be investigated as to their lateral and footwall facies of kaolinization underneath the quartz core. It is aimed determining the degree and to distinguish the type of hypogene from supergene kaolinization which can be superimposed on the hydrothermal alteration. Today the supergene kaolinization is present only as relic often overestimated in relation to its predecessor. In the Borborema Pegmatite Province,Brazil, mineralresources associated with therare element pegmatites comprise apartfrom Be,Nb–Ta, Li, and Sn, gemstones, such as the rare Paraiba tourmaline. Among the industrial minerals besides quartz and feldspar kaolin is of interest in thesepegmatites which were subjected to intense chemical weathering under tropical climatic conditions (Beurlen et al., 2001) (Fig. 39a).Inthe environsof Pleystein, the kaolinizationis moststrongly among the aplitic and pegmatitic rocks of the Hagendorf –Pleystein Pegmatite Province, Germany (Fig. 39b, c, d). In the zone where kaolinization is most intensive only muscovite/sericite and sporadic tantalite –columbite survived in a matrix of kaolinite. There is conspicuous variation in the kaolinization underneath the quartz core of the Kreuzberg Pegmatite (Fig. 39b). Two subzones, separated from each other by a subparallel quartz vein evolved in the footwall aplite. The lowermost zone of the aplite was much stronger affected by the hypogene kaolinization than the uppermost zone immediately underneath the quartz core (Fig. 39b). This type of mineral association was also recognized in various unzoned kaolinite aplites around Pleystein, Germany, devoid of any quartz coreimpoundingthe ascending hydrothermal�uids (Fig. 39c,d). In the aplite granites the original structure has been preserved much better than in the aplites. Kaolinization in these reference aplites and aplite granites resulted from the combined effect of hypogene and s upergene alteration. Besides the above kaolinized pegmatites from Germany, the site most well studied is the granitic cupola at Montebras,France, whichbelongs to the highly kaolinized Chanon Granite (Dudoignon et al., 1988). The hydrothermal alteration was accompanied by different types of greisen formation subsequently overprinted by an extensive kaolinization process, which affected the entire granitic bodies. In the Chanon granite, the greisens are characterized by a Li mica–quartz – tourmaline assemblage which are surrounded by concentric alteration zones. Strong hypogene kaolinization has also affected some of the Be pegmatite (emerald) in the Ural Mountains, Russia (Fig. 39e) (Fersmann,1940 cited in Schneiderhöhn, 1961). For comparisonthe supergene kaolinization of the Salpond Pegmatite, Southern Ghana, has

525


been shown in a cross section inFig. 39f. Theuppermost part of the pegmatite and its surrounding wall rocks are affected by the tropical weathering almost to the same extent down to the lower boundary of the weathering front. 5. Processes in the exocontact of pegmatites and within pegmatites

5.1. Skarn mineralization and contact metamorphism

In rare-elementpegmatite provinces with Sn–W-, REE-,U-Th-, B-, Pand Mo-bearing pegmatites, skarn mineral associations occur at a distal as well as proximal position relative to the pegmatites-for de �nition of skarn seeSection 4.1.1. This is also valid forsome of thepegmatite provinces containing predominantly industrial minerals and gemstones such as feldspar, feldspathoids (scapolite), zeolite, corundum, garnet or graphite (Table 2). Pegmatite-related skarn mineralization abundant in rare elements or industrial minerals has been dealt with in the pertinent subsections of Section 4 while placing the emphasis on the accumulation of elements and minerals in the metacarbonates (Table 2). Another effect, denominated in the pertinent literature as contamination of the felsic melt, is often very dif �cult to constrain, although mineralogical evidence such as the presence of Ca,Mg,(Fe)-rich minerals clinopyroxene (diopside to hedenbergite), amphiboles (tremolite, edenite, hastingsite), Mg-rich cordierite, phlogopite, scapolite, titanite, epidote, and/or calcite are, in places, very common (Žáček, 2007; Novák, 2013). Novák (2013) subdivided this kind of contamination found in pegmatites corresponding to the temporal relationship between pegmatite formation and contamination. He published a tripartite scheme into (1) pre-emplacement contamination of the melt, (2) post-emplacementcontamination of the melt, and (3) (3) post-emplacement contamination of solid pegmatite. Based upon the current studies it seems advisable to place another stage between (1) and (2) which is synonymous with the skarn mineralization and syngenetic with the initial stages of pegmatite emplacement — see Fig. 40a, b. This is the reason why it has been referred to in this context and the term pegmatite-skarn was used as separate entity for a wide range of mineralizations. The pre-emplacement contamination of melt is the most dif �cult one to come to grips with and well-documented examples, such as the Bližná I pegmatite, Czech Republic, are rare (Novák et al., 2012). Post-emplacement alteration involves in-situ contamination of a pegmatite melt from the host rock. Hydrothermal (subsolidus) contamination is characterized by alteration of a solid pegmatite by �uids in�ltrating (or diffused) from host rocks after thermal and �uid reequilibration of pegmatite and host rock. In the Naje tourmaline deposit, Nepal, a syn-emplacement contamination took place as a tabular zoned pegmatite was emplaced at the contact between banded gneisses and overlying calcsilicate rocks north of the Main Central Thrust in the Himalaya (Aryal, 2001) (Fig. 40a, b). The felsic melt incorporated the calcsilicate rocks containingdiopside (Fig. 40a, b). Apart from metacarbonates and the more siliceous calcsilicate rocks, basic and ultrabasic rocks may also behave as contaminants a exempli�ed by the Bližná I pegmatite, Czech Republic, and the basic igneous rock slaps in the Tanco pegmatite, Canada (Van Lichtervelde et al., 2006). Another thermal effect which often went unnoticed in pegmatite �elds is contact metamorphism, which can directly be connected with the skarn mineralization as well as the pegmatites. Porphyroblasts of grossularite (hessonite), vesuvianite, zoisite, and minerals of the diopside-hedenbergite s.s.s can easily be seen with the unaided eye in the �eld and having a UV lamp at hands, even the scheelite dissemination associated often with them may be detected at site. These Ca minerals typical of skarn were only recently identi�ed west of the Hagendorf –Pleystein Pegmatite Province, Germany, associated with aggregates of wollastonite, indicative of the high-grade contact

metamorphism. The classical metamorphic process leading to wollastonite when CaO and SiO2 react with each other can be found in almost each textbook of petrology. Observations in the �eld at Hagendorf, Germany, suggest that the XCO was rather high and a temperature of 600 °C existed at a depth of 2 km below ground, corresponding to 500 bar. Doubling the depth needs temperatures of between 650 and 670 °C to produce wollastonite. Whatever temperature of formation has been invoked in relation to depth, one thing is for sure. There is a thermal anomaly in the exocontact to the west of the pegmatite province. At the endocontact the chemical composition of the black Feenriched sphalerite from the Kreuzberg Pegmatite lends mineralogical support to this idea of a contact-metasomatic–contact-metamorphic processes related to the emplacement of pegmatites in the study area. The “hot spot” of the rare metal-bearing pegmatites of the Hagendorf – Pleystein Pegmatite Province, Germany, lies in the environs of Pleystein rather than in the Hagendorf area, asymmetrically to the entire pegmatitic ore � eld. The thermal event should not be taken as the ultimate heat source accountable for the entire process of emplacement and alteration of the pegmatites. As large complex pegmatite bodies formed by multi-stage processes, it needs to single out the process in question and correlate the heat event triggering the contact metamorphism in the exocontact zone with the individual process inside the pegmatite, proper (Dill, 2015). The above processes are intracrustal, but as far as the heat source is concerned a subcrustal source cannot be excluded, particularly in view of the highest grade of contact metamorphism and the presence of intermediate to basic intrusive rocks related in space with these alteration phenomena. In the Hagendorf –Pleystein Province contact-metasomatic and contact-metamorphic processes at its western exocontact is much more intensive than what has been observed around the nearby Flossenbürg Granite which for quite a long time has been considered as the parental granite for the pegmatites and aplites of the Hagendorf –Pleystein Province. It is a major setback in the attempt to link a nearby granite complex with a pegmatite province nearby. Although both of them belong to the late Variscan thermal event, the temperature regime was strikingly different for the granite and the pegmatite. In the CMS classi�cation scheme, a rock like that may show up as Nb–Be pegmatite-(skarn). 2

5.2. Episyenitization and albitization

Episyenitization and albitization affected granites and pegmatites alike. These postgranitic or postpegmatitic alteration phenomena result in a replacement of quartz while producing an igneous rock composed almost entirely of sodic plagioclase. Using the double-triangle diagrams thenewly formedrock plots in the �eld ofsyenites orhas tobe called an albitite (Streckeisen, 1980). The outward appearance is that of a porous and highly permeable magmatic rock which behaves like a reservoir rock in a hydrocarbon deposit as mineralizing �uids percolate through these episyenites and precipitate ore minerals at an economic grade, mainly U oxides, -titanates and -silicates (Dill, 1983a,b) (Fig. 41a, b). Episyenitization has been recorded from different regions in Europe, from Precambrian through Mesozoic felsic magmatic rocks (Dill, 1983a,b; Cathelineau, 1986; Petersson and Eliasson, 1997; Hecht et al., 1999; Boulvais et al., 2007 ). While the initial stages of this alteration are closely resembling each other, involving a desilici �cation or dequartzi�cation of the host rock to almost completeness, the replacing products can signi�cantly differ fromeachother. There are pure feldspar episyenites and mica episyenites, which end up in muscovite-enriched igneous rocks. The episyenites may also contain calcite and dolomite and even zeolite (heulandite and stilbite). This is the case in the area in NE Bavaria (Fig. 41b). Dosbaba and Novák (2012) recorded from theV ěžná I pegmatite,Czech Republic, quartzreplacementby “kerolite”, a varietyof talc (Fig.41c). The desilicated graphicpegmatiteis hosted by a serpentinized harzburgite and the source of Mg “ just round the corner”. According to the authors, this alteration likely proceeded at

526


a

Shearing

Accommodation space

b

Fig. 47. a. The zonation of the Greenbushes pseudopegmatite, Australia, and its relation to the host-shearzone (Partington ( Partington et al., 1995). 1995). b. The fold-related metamorphogenic Ag-bearing

Pb–Zn vein-t vein-type ype deposi deposits ts Ramsbec Ramsbeckk in the Rheini Rheinisches sches Schief Schiefergebirg ergebirge, e, German Germany. y. Steepand �at-lyingPb–Znveinsrelate Znveinsrelatedd to thefoldi thefoldingof ngof theRamsb theRamsbeckQuar eckQuartzit tzite. e. Mov Moveme ementparall ntparallel el the shear planes gave rise to the accommodation space for Pb –Zn mineralization (quoted in Dill, in Dill, 2010). 2010).

temperat temper ature uress in therange100 to 30 3000 °C andunde andunderr a pre pressu ssure re reg regimeof imeof below ~0.5 to 1.0 kbar, under high activity of alkalis but low tectonic stress. While the physica physicall conditions seem to be plausible and can also be applied to similar s imilar types of alteration elsewhere, the tectonic setting is different from what has been revealed during the U exploration in the 1980 19 80 in the gra grani nitic ticare areas as alo along ng the we weste stern rn edg edgee of the Bo Bohem hemia iann Mas Massi sif f (Fig Fig.. 41 41a,b).The a,b).The ma mapp of Fig. Fig. 41 41bb ilillus lustra trates tes a str strong ongly ly fra fractu ctured red mar margi ginn of an uran uranifero iferous us gran granite,with ite,with seve several ral cris criss-cro s-crossingfaults, ssingfaults,one one set (NW–SE) is unm unmine ineral raliz ized ed bu butt str strong ongly ly my mylon loniz ized ed and andthe theoth other er set str striki iking ng N–S to NNW–SSE gave host to dolomitic episyenites. The metamorphic country rocks of the granite are made up of metapelites with several horizons of marbles and calcsilicates. The � nal product of episyenitization, be it a

phyllosilicate or a carbonate is closely controlled by the country rocks as exempli�ed by the above sites undergoing intensive episyenitization. It mayy be a con ma contac tactt or pro proxim ximal al epi episye syenit nitiz izati ation, on, e.g e.g.,., V ěžná ěžná-t -typ ypee or a di dist stal al episyenitization, e.g., Hebanz-type. The reader is also referred for physical–chemical discussion to the paper published by Thomas by Thomas and Davidson (2015). (2015) . Episyenitization is characterized by a replacement of quartz and accompanied by a strong increase of the albite component in the feldspar. Unlike Unli ke the afore aforementi mentioned oned carbo carbonate nate miner minerals als and phyl phyllosil losilicat icates es whichorigi wh ichoriginat nated ed fro from m ele elemen ments ts rel releas eased ed fro from m thehost roc rocks ks andcoun andcountry try rocks roc ks of the thegra granit nitee andpegma andpegmatit tite, e, the thesod sodiu ium m com compo ponen nentt can cannot notsim simpl plyy be supplied by a decomposition of calcium –sodium feldspar. Sodium has

527


Run of mine

Flow sheet for Cassiterite Tantalite Wolframite

Screen

coarse

Jaw crusher

fine

> 10mm

Screen

Cone crusher

< 10mm Concentrate coarse

Jig

tailings

Concentrate coarse

tailings

Rod mill

Jig

> 1mm

Screen concentrate

< 1mm

Taillings disposal

Spiral tailings

tailings concentrate

Spiral

Shaking Shaking table

tailings

Concentrate fine

Fig. 48. Flow sheet to show the bene �ciation scheme for metal oxides in pegmatites. (Redrawn from a �ow sheet designed by H. Wotruba).

been derived beenderi ved from a deep deeper, er, subc subcrust rustal al sour source, ce, alt althoug houghh alb albitit itites, es, part particuicularly la rlytho those se ass associ ociate atedd wi with th ura uraniu nium m dep deposi osits ts can be fou found nd in S- as wel welll as A-typegrani A-t ypegranites tes.. The cla classi ssicalstudi calstudies es dat datee ba back ck on the ear early ly in inves vestig tigat ation ionss in the former Sowjet Union (Dobretsov, (Dobretsov, 1963; Kalyaev, 1980). 1980 ). Metasomatic U deposits of this kind are situated at Espinharas, Brazil, Tete, Mozambique, Zholtye Vody, Ukraine (for description see box underneath), Kitongo, Cameroon, and Valhalla near Mount Isa in Australia and mostly are bound to deep-seated lineamentary fault zones which acted as pathways for the hydrothermal �uids forming the albitites (Oesterlen ( Oesterlen andVetter, andVett er,19 1986 86;; Co Conno nnors rs andPage,1995 andPage,1995). ). Toge Together ther with withthe the alb albiti itizati zation on andthe emp empla lacem cement ent of ura uraniu nium, m, ThTh-,, P- andREE-b andREE-bear earing ingmin minera erals ls wer weree introd int roduce ucedd int intoo the al alter tered ed hos hostt and wa wallll roc rocks. ks. In Secti Section on 4.2.3 emphasis was placed on the role of albitites and episyenitization during the accumulation of emeralds in the contact zone of basic schists, pegmatites and granites (see also Fig. also Fig. 39e). 39e). The Nova Mine, near the town of Zholtye Vody, Ukraine worked a polymetallic polymetal lic primarily iron ore enriched in scandium, uranium and rare earth elements. The scandium resource was estimated to be be 7.9 Mt grading 105 ppm scandium, and the mine was believed to be the only primary

scandium scandi um min minee in ope operat ration ion in the wor world. ld. Its min minera eraliz lizati ation on is rel relate ated d to alkaline magmatic activity (Duyvesteyn (Duyvesteyn and Putnam, 2014). 2014).

Albitized Albiti zed gran granite itess and alb albiti itites tes in Kaz Kazakhs akhstan, tan, Taji Tajikist kistan, an, Uzbekistan, Norway and Canada are not only host or reservoir rocks for rare-element concentrations but they are also worked for feldspar, since natural processes have already done the job used by done in a processing plant (Harben ( Harben and Kuž Ku žvart, 1996; Potter, 2007). 2007 ). This alteration can also be addressed in the CMS classi �cation scheme, it is either a dolomite –feldspar pegmatite, as in the Hebanztype or a talc –feldspar pegmatite pegmatite in case of V ěžná-type. ěžná-type. 5.3. Metamo Metamorphoge rphogenic, nic, magma magmatogeni togenicc and hydro hydrothermal thermal pegmatitic processes proce sses

The temp temporalrelati oralrelation on betw between een the encl enclosingcountr osingcountryy rock rockss and peg peg-mati ma titi ticc roc rocks ks al allow lowss for a tri tripar parti tite te su subd bdivi ivisi sion,a on,a fac factt whi which ch is tak taken en ad ad-equate account in the CMS classi�cation scheme of these felsic mobilizates mobiliza tes with the introduction of metapegmatite metapegmatites, s, pegmatoids and

528


pegmatites sensu stricto. pegmatites s tricto. They formed pre-, syn- and post-kinematic post-kinematic in relation to the structural disturbances. The different processes, that might be operative in aplites and pegmatites located in an ensialic orogen are listed in Table in Table 12. 12. At the beginning of pegmatitization sensu stricto discussed in this book an initial metamorpho-tectonic stage is characterized by syn- to late kinematic mobilizates. mobilizates. The transition from schlieren of pegmato pegmatoids ids to pegm pegmati atites tes s.st s.str. r. sug suggest gestss thatthese mel melts ts were wereverymobile verymobile,, and separated gradually from their site of formation through selective separation such as � lter-pressing and seismic-pumping along with thrustal motion. Intracrustal and subcrustal processes of element mobilization have acted in the same direction by providing heat and mobilizing elementss fromdifferen ment fromdifferentt sour sources ces to crea create te in a mul multist tistage ageproc process essaa comp complex lex rock cal called led peg pegmati matite te s.st s.str. r. Acco Accommod mmodati ation on spac spacee is prov provided idedfor for stoc stockklike li ke bo bodi dies es in the hi hingeareas ngeareas,, fortabu fortabularones larones al alongthe ongthe li limbsof mbsof an anti ticl cliinal structures following the rules of mimic tectonics and along shearzones where pegmatites got, in places, dismembered. Multi-p Mul ti-phase hase pegm pegmatit atitizat ization ion may invo involve lve lat latee kine kinemati maticc (to postkinematic) subcrustal magmatic mobilization which affected the pegmatites tes” and lea leadd to oreore-bear bearing ingalte alterati ration on “older granites” or “older pegmati zones such as greisen and stockschei stockscheiders ders — see see Section Section 4.1. 4.1. In the postpostkinematic stage advanced fractionation of the melt takes place, which

along the margin grades into contact metasomatic processes with the crystalline country rocks – see see Section Section 5.1 – and conduced to a reaction rim and contamination of the melt. Autometasomatic Autometasomatic retrograde reactions were observed in large stocks or thick tabular bodies sealed off from the country rocks. Small tabular bodies only show an interaction of their melt with the crystalline country rocks whereas reactions with preexisting minerals in the pegmatite itself are scarce. Mineralization caused by younger individual granitic or subvolcanic stocks in the pegmatite at shallow depth was called epithermal. These young granitic or subvolcanic intrusives were intruded along deep-seated lineamentary fault fau lt zo zonesat nesat thetime whe whenn thebase thebasemen mentt bl blockand ockand thehost thehosted ed pe pegma gma-tite ti te we were re go goingto ingto be up upli lifte ftedd so tha thatt we weath atheri ering ng anderos anderosio ionn co coul uldd wo work rk their the ir wa wayy do down wn to dep depth. th. Sti Still ll un under dernea neath th the le level vel of ero erosi sion on and pri prior or to the stage when the epithermal mineralization took full effect, pockets, cavities and miaroles come into existence in granitic pegmatites under moderate pressure — see CMS classi �cation scheme (Section 3.2). 3.2). The structural and environmental processes operative in and around the pegmatites pe gmatites responsible for the epithermal mineralization also paved the way to unconformity- or in geomorphological terms, term s, pene peneplai plain-rel n-relatedvein-ty atedvein-type pe depo deposit sitss whi which ch prov proven en by rad radiome iomettric age dating evolved near the surface, while at depth magmatic processes were still at full swing. In the aftermaths of these processes

Fig.. 49. Mini Fig Mining ng pegm pegmatit atites es sma small-s ll-scaleand caleand larg largee scal scale: e: TheCapoe TheCapoeiraMineexploi iraMineexploitedfor tedfor Par Paraib aibaa Tou Tourma rmalin linee in Bra Braziland ziland theRössi theRössing ng Min Minee nea nearr Swak Swakopm opmund und,, Nam Namibiaminedforuraniu ibiaminedforuranium. m.

See drill rig, trucks and roads for scale (open pit photographs courtesy of Rio Tinto Rössing Uranium).


operative at the brink from the supercritical to the subcritical hydrological regime, the hydrothermalalteration of the primary pegmatitic minerals played an ever increasing part in a rather mobile geodynamic setting. Mineralization gradually converts from alteration intrinsic to the pegmatite into an alteration driven by extrinsic factors,e.g., a superimposition of a distal mineralization of Alpine age ontoa mineralization pertaining to the Variscan one. The schematic pathwayof the geological evolution in a pegmatite is a mixtum compositum elaborated for the pegmatites in the Central European Variscides, along the western edge of the Bohemian Massif. Some processes may be more prominent in one or the other pegmatite than described while others are missing (Dill, 2015). The latest processes affecting the pegmatitic rocks forms part of the supergene alteration which was extensively treated in Section 4.17. 6. Mineral deposits associated with pegmatitic rocks

6.1. Variscan-type metallogenic setting and pegmatites

In the Variscan-type, ensialic orogen, where most pegmatitic rocks from metapegmatites, through pegmatoids and pegmatites s.st. to plutonic pegmatites formed, a characteristic assemblage of nonpegmatitic mineral deposits is associated with the various types of pegmatitic rocks and their � ner-grained aplitic equivalents. The varied spectrum of mineral deposits has been subdivided into four groups, a �fth category, is transitional into the adjacent geodynamic setting denominatedas ensimatic (Fig.9a) (Dill, 1989; Dill et al., 2008b,c).Adetailed treatment of the non-pegmatitic mineral deposits in a particular geodynamic setting may help delineate pegmatite � elds of the aforementioned structural types, vice versa the structural types of pegmatites can also be applied in terms of marker types for a special physical regime and thus used as an ore guide for non-pegmatitic mineral deposits in the other way round. Pegmatites are closely interdigating with non-pegmatitic deposits. Type-I mineral deposits encompass stratabound and, in places, also stratiform and timebound mineral deposits. Sediment-hosted massive sul�des prevail over volcanic-hosted massive sul �des in basement sections prone to pegmatites. It is mainly pyrite-pyrrhotite-bearing Cu –Zn deposits and sedimentary exhalative Fe deposits. There is a wide range of U–Cu–Mo–Sb–Zn–REE-bearing low-grade-large-tonnage deposits, the most remarkable of its kind are the black-shale-hosted ones. The Early Paleozoic Graptolite Shales and Alum Shales are even timebound. During the same period of time pegmatites evolved, which according to their different geodynamic setting were subjected to a different type and degree of regional metamorphism. Another commodity is graphite which is oneof thefew minerals which owes its existenceexclusively to the high-grade regional metamorphism and also appears in pegmatitic rocks(Section4.16). The pertinent pegmatitic deposits for type-I mineral deposits belong to the group of metapegmatites — see also CMS classi�cation scheme (Section 3.2.1). Type-II mineral deposits are called thrustbound, fold-related and metamorphogenicin origin. Activationof the continental margin resulted in the initiation of southward subduction in the early Late Devonian in the Central European Variscides, where most of the examples cited here have derived from. The structurally-controlled ore deposits containing Sb, Pb, Zn, Cu sul �des, Au and siderite, show pervasive textural distortion and strong mylonitization. Base metals, Sb, Au and siderite are related to shear-zones and cleaved (meta)psammo-pelitic series, that developed along the fold axesof the Variscan anticlines.The various mineral associations in the faultbound deposits are subdivided as follows: silver-bearing base metal, copper-bearing iron-oxide and selenium, siderite –copper –lead–zinc-, gold–antimony–arsenic (mesothermal Au–Sb vein-type), gold–tellurium veinlets, and gold – tungsten vein deposits. Polymetallicgold–stibnite mineralizationoccurs in a proximal position relative to the anticlines cored by the late

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Variscan granites, whereas the monotonous stibnite veins, lacking Au of economic grade, are located in a more distal position relative to these “ high-heat zones”. Besides these metal deposits thrust-bound talc and asbestos deposits in (ultra)basic igneous rocks occur. Among the pegmatitic deposits feldspar –quartz pegmatoids and quartz lodes plus quartz pegmatites have to be attributed to these thrustbound, fold-related and metamorphogenic deposits (Sections 4.10.2, 4.11). The feldspar- and quartz-enriched pegmatitic rocks formed at greater depth are equivalent to the metal thrustbound and fold-related deposits emplaced at a more shallow level. This is demonstrated in pronounced way as the non-pegmatitic mineral deposits in the Rhenohercynian Zone, barren as to pegmatites, are compared with the pegmatitic deposits in the Saxo-Thuringian Zone — see also Section 2.1. Type-III mineral deposits are collision (granite)-related deposits. By the end of the Variscan orogeny the convergence in mid-Carboniferous times resulted in the emplacement of abundant syn- and postorogenic granites and the formation of granitic pegmatites and pegmatites sensu stricto as separate entities (Section 4). The passage from the shear- and thrustbound type-II to the granite-related type-III deposits is the most decisive part for the emplacement of pegmatitic rocks since it marks the metamorphogenic–magmatic initial stages during the emplacement of the pegmatites in context with particularkinematic effects. The granitic pegmatites are exclusive to the type-III deposits. In the ensialic orogen the following mineral associations occur: Tin–tungsten–molybdenum vein-type, greisen and skarn deposits, lead–copper– zinc–silver vein deposits, polymetallic and monotonous uranium veintype often in episyenitic deposits and talc (soapstone) replacement deposits in carbonate rocks — see Section 5.2. While type-II metal deposits formed at a shallower level than the contemporaneous pegmatitic and aplitic deposits, the feldspar–quartz and polymetallic (granitic) pegmatites during the Permo-Carboniferous cameintobeing at a similar depth as their non-metallic deposits. At the very end mineralizing processes intrinsic to the pegmatites and mineralization close to the unconformity are telescoped intoeach other — see Section5.3. Thetransition from late type-III deposits into early type-IV deposits, such as the uranium and �uorite deposits with fetid �uorite is gradually with no sharp boundary (Dill et al., 2008b,c). Type-IV mineral deposits began forming simultaneously with the mineral deposits of type III. Radiometric age dating of U oxides present in types III and IV ore mineralization prove this idea. While the primary mineralization of the rare element pegmatites faded out at depth unconformity-related vein-type deposits evolved near the paleopeneplain which capped the uplifted basement blocks and gave host to different types of supergene mineral deposits. Peneplanation and etchplanation (Twidale, 2002) under arid to (sub) tropicalclimatic conditionsoccurred during theselate Variscantime. The late Variscan/early Alpine unconformity has become a geohydraulic plane for a great variety of epigenetic deposits which were emplaced where this unconformity was intersected by (sub)vertical fault zones. Meso- to epithermal polymetallic mercury-precious metal vein-type deposits, uranium–molybdenum –copper vein-type and stratiform deposits in volcanosedimentary series, uranium-bearing � uorite-barite and base metal vein-type and sandstone-hosted deposits and iron-base metal-barite vein-type and replacement deposits are bound to the post-Variscan unconformities — see also intra-pegmatitic epithermal mineralization in Section 5.3. They are found within Upper Carboniferous through Lower Jurassicigneous rocks and in platform sediments, or immediately beneath the unconformity in Paleozoic basement rocks. Supergene deposits with kaolin, Sn and U are also related to this peneplanation. The younger stages of this era of mineralization at shallow depth and across the peneplain are contemporaneous with the onset of the secondary mineralization in the rare-metal pegmatites. In the stable cratonic shelf of the Paleozoic Variscides another type-V mineralization evolved. This igneous-related-lineamentary bound mineralization with Bi–Co–Ni-, and Pb–Zn–Ba–F vein-type deposits cannot immediately correlated with the secondary mineralization of the

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pegmatites for lack of age data. Publications are scant and there is still a considerable lack of information as to the geodynamic setting and the age of formation of the pertinent mineral assemblages (Wagner and Lorenz, 2002; Ondruš et al., 2003a,b). A Nb–REE mineralization during the Cenozoic in the wake of some alkaline magmatic complexes and carbonatites hallmarks a mantle-derived rare element mineralization in Central Europe. The driving force for this Alpine remobilization in the extra-Alpine Region has not yet been fully understood in geodynamic terms. Initial phases of extension in the Proto-Atlantic Ocean and mantle processes in the Penninic Ocean of the Alpine Region (Alpine Tethys) are possible candidates to explain this mineralization.Perhaps,the Cu–Co–Ni–Bi–Ag mineralization at Grimentz, Switzerland, in the Permo-Carboniferous Casanna Schists of the Middle Penninic Bernhard Nappe (Briançonnais) may bridge the gap between the extra-Alpine Ag–Bi–Co–Ni formation and the geodynamic–metallogenic evolution in the Alps (Halm, 1945). It is a moderate or distal representative of the ensimatic metallotect when compared with the carbonatite complexes and alkaline magmatic complexesin,e.g.,Brazil andSub-Saharan Africa. Andit canbe considered as a typical late-stage response of ore mineralization in the Variscan ensialic or collisional orogen as it became reactivated in the course of the newly formed Alpine orogen which shows a more ensimatic component in its geodynamic evolution than the Variscan-type equivalent but less pronounced than the Andean- or Arc-type. Pegmatites did not form in Central Europe in connection with these intrusive rocks. When discussing non-pegmatitic ore mineral deposits with pegmatitic deposits, there is a logic for another question: Which mineral deposits are negative markers and exclude the presence of pegmatitic deposits in the geodynamic setting? There are no porphyry-type Cu– Au–Mo deposits, no podiform chromite deposits, no Ni–Co deposits, no primary PGE deposits, no epithermal-type Cu–Au–Ag–Mo–(As–Sb– Hg) deposits, no ophiolite-hosted Cu –Au deposits and only minor VMS Pb–Zn–Cu–Ba deposits in crustal sections prone to pegmatite deposits. These metal deposits are common to Andean and Island-Arc settings (Fig. 9a). Divergent plate boundaries as they have reached an advanced level of spreading are detrimentalto the accumulation of pegmatitic rocks. Thinning of the crust taken to the extreme is not what pegmatites like. Convergent plate boundaries are n o favorable sites for pegmatite deposits either. They neither form in the principle arcs or its inner sides, nor show these deposits up in arc-related rifts. As we have learnt in this section they like crustal thickening, when subduction converts into a collision of plates, with nappes being stacked and piled up, so turns an infertile setting into a fertile one. When the stable craton or thickened crust start splitting up again, the early stages of rifting or failed rifts, and triple junctions create another birthplace of pegmatite deposits (Section 6.2, Fig. 9a). The chance to create pegmatites diminishes the more advanced the level of rifting is. 6.2. Rift-type metallogenic setting and pegmatites

The embryonic stage of rifting and intracontinental hotspots are the second favorable geodynamic setting to emplace pegmatites of speci �c types (Table 3, Fig. 6a, c). As these mineral deposits do not form in a newly-generated oceanic crust or within a newly-emplaced arc but still emplaced in a thickened crust, complex rare element pegmatites should not be taken any longer as a surprise (see Eastern Africa, Brazil). It is the relative speed of plate motion that counts in physical and chemical terms as it comes to the emplacement of rift-type related pegmatites and mineral deposits associated with them; the speed is crucial for the feeding of mantle-derived material into the mineral deposits, including the pegmatites and controls the lithospheric–asthenospheric interaction and generation of heat driving the pegmatites to come into existence. If the motion is too fast and a set of multiple vents fosters the formation of basaltic lava �ows across the preexisting basement rocks this crustal section has no high potentialto emplace pegmatites. But a young plateau

basalt does notexclude a slow motionduring earlier periods (!). Themost favorable targetareasarethose with almost no motionof thehotspot and the overriding crust. Peralkaline and peraluminous felsic igneous rocks (A-type granite suite) are produced s ide-by-side with carbonatites. In Uganda, Be–REE–Zr–Nb/Ta pegmatites are associated in space with REE–Nb carbonatites (pyrochlore). To correlate the rare-elementpegmatites and the non-pegmatitic element associations in the above magmatic complexes locatedin an embryonic or a failed rift,the various non-pegmatiticmineraldepositshave been cited with their coding according to Dill (2010): 1. Sn–W Post-granitic endo- and exogranitic greisen-vein in A-type granites and breccia-pipe deposits (12b DE) 2. Be-bearing alkaline intrusive rocks (nepheline syenite) (14a E) 3. Be- and Y-bearing alkaline intrusive rocks (nepheline syenite) (24d E) 4. REE–P–Nb–Ta–Y –F–(Be–Zr–Th) deposits related to carbonatites (24a E) 5. REE–P–Ti deposits related to alkaline igneous complexes (24b E) 6. Th deposits related to alkaline intrusions and carbonatites (26b E) 7. Fluorite deposits related to U –REE carbonatites and alkaline intrusive rocks (32a E) 8. Cryolite deposit related to metasomatic A-type granites (32b E) 9. Nb-enriched deposits related to alkaline igneous complexes and carbonatites 10. Pyrochlore-dominated concentric shell-type intrusions and carbonatites (13a E) 11. Nb-perovskite-dominated laccolites (13b E). For a more detailed treatment of these individual deposits and further literature the reader is referred to Dill (2010). 6.3. Alpine-type metallogenic setting and pegmatites

The CentralEuropean–Himalayan Fold Belt canbe takenas a case-inpoint for a geodynamic setting where elements have been incorporated from the adjacent pre-consolidated stable crustal sections which sufferedfrom differentorogenies prior to the Mesozoic–Cenozoic kinematic–metamorphic processes. For regions in the Far East, it would go far beyond this review on pegmatites and it would be too premature to make an attempt to show how rare-element pegmatites have been incorporated from the adjacent cratons into the newly formed Himalayan fold belt. The evidencing situation for these Asian regions is too weak and the area lacks any coverage almost similar to the Central European Mesozoic–Cenozoic Alpine Mountain Chain, located immediately south of the Paleozoic Variscides, its predecessor ( Figs. 2, 6a). As an example for the reactivation of non-pegmatitic minerals, the Bi–Co–Ni minerals assemblage has already been quoted in Section 6.2. It has some kind of a transitionalstatus and marking theonset of rifting, or when a consolidated crustal section starts weakening again, while true rift-related mineral deposits listed in Section 6.2 have not yet been emplaced. Besides the often discussed pseudopegmatites in the Austrian Alps, there are some examples which can be referred to as reactivated deposits fromthe Central EuropeanVariscides. In the westernmost branch of the Alps, the Salau W –Au skarn evolved (Fonteilles et al., 1989). The skarn deposit is hosted in Devonian carbonates and was intruded by a late Carboniferous stock. The Hercynian orogeny involved polyphase deformation, regional metamorphism of greenschist facies, and late intrusions of granite–granodiorite. During the �rst stage (540 to 450 °C), skarn formation was followed by pyrrhotite –scheelite–quartz–calcite mineral assemblage. In the second stage (450 to 350 °C), the main ore stage with scheelite, pyrrhotite, arsenopyrite, sul �des and some gold developed. It is a type-III granite-related deposit which may also be encountered within the collisional Variscan orogen outside the Alps. The younger Alpine deformation and metamorphism had little imprint on this incorporated deposit. The pendant as far as the pegmatite deposits


are concerned is the Albera pegmatite � eld in the Eastern Pyrenees, France, with its (Nb/Ta–U)–Be–Li–P pegmatites (Malló et al., 1995). The Central European Alpine Fold Belt has been investigated again and again, and it is not really a surprise to see in some cases a back and fro with regard to the principles of ore concentration. Many deposits formerly interpreted as epigenetic were re-interpreted as stratabound and timebound to Paleozoic periods (Tufar, 1972; Maucher,1974). Not long after thependulum hasswung to theopposite side again (Belocky et al., 1991; Pohl and Belocky, 1994 ). Nevertheless, the deposits of Variscan age form an integral part of the metallogenic evolution of the Alps. In the Italian Alps S of Innsbruck, the Monteneve/Schneeberg mine, Italy, forms part of a horizon mineralized with Zn –Pb minerals that extend over about 20 km, within a paragneiss formation of preSilurian age (Frizzo et al., 1982). Meta-pegmatites were recorded by Thöni and Miller (2004) from the Ötztal Basement, in Tyrol (Eastern Alps), Austria. Garnet-whole rock or garnet –feldspar Sm–Nd isochrone ages span the interval 445 ± 3 through 473 ± 3 Ma, indicating a Middle to Late Ordovician heat event which lead to the emplacement of these pegmatites. The Alpine Mountain Range has metapegmatites similar to those from the western edge of the Bohemian Massif — see allochthonous ZEV and Tepla Barrandian Zones. Meta-pegmatites and type-I stratabound SMS deposits are found side-by-side in a similar way to the Variscan basement blocks also outside the Alps. Two vein-type gold deposits in the Swiss Alps at Salanfe and Astano, Switzerland are grouped under the heading of thrustbound gold–tungsten deposits (type-III deposits). At Salanfe, sul �des and arsenides associated with Au were found in a scheelite-bearing skarn of the Aiguilles Rouges Massif ( Chiaradia, 2003). Anatexis and leucogranite formation occurred at peak metamorphic conditions (P: 0.45 GPa; T: ~650 –700 °C). This metamorphic event, dated at 317 Ma in the adjacent Mont Blanc Massif, was related to dextral transpression following Variscan continental collision. Astano, Switzerland, is located within the Southern Alps and contains a typical mesothermal Au –(Sb) vein-type mineralization with a variegated spectrum of Sb sul �des. Here, the complicated polyphase metamorphic history inducing several stages of hightemperature Alpine remobilization renders it dif �cult to derive any information on the genesis of the deposit. This element combination is similar to the Variscan thrust-bound Au –As–Sb vein-type deposits in the extra-Alpine part of Central Europe and thus a Variscan age of the Astano deposit seems plausible. In the Western Alps in Switzerland and France, there are Variscan deposits but equivalent Variscan-type pegmatites are absent. A quick look at the map of Fig. 2a. will bring us a bit closer to the solution of this enigmatic situation. At the western margin of the Alpine Fold Belt, where this Mesozoic–Cenozoic orogeny fades out, pegmatitic and non-pegmatitic rocks were incorporated with only moderate overprinting, so that the same terminology can be applied as for the Variscan-type predecessors outside the Alps. In the Western Alpine Fold Belt, non-pegmatitic deposits have strongly been overprinted in some sites, so that their origin can less clearly be determined due to the adjustment of their original mineral assemblage to the subsequent Alpine metamorphic events. Wolframite and scheelite mainly hosted by amphibolites and found in quartz –tourmaline veins have been reported from the Moldanubian Zone of the Black Forest (Gehlen von, 1989). Pegmatites do not occur in these Variscan massifs in front of the Western Alpine Mountain Range and consequently do not show up in the ancient massifs inside the Western Alps. Reactivation may show up in different phases, dependent on various factors such as the temporal gap, andthe depth relation, to mention only the most signi�cant factors. Therefore a protore–ore correlation can much better be achieved in Europe than in some other orogens of Precambrian age, but the stimulus-reaction principles are the same.

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7. Economic geology of pegmatite-related elements and minerals

The economic geology of individual pegmatite deposits is often dif �cult to assess, excluding some of the “giant deposits ” sensu Laznicka (2005, 2010, 2014) . Laznicka (2014) did not discount pegmatite deposits in his most recent study and mentioned the discovery of Greenbushes in 1920 for Sn, but he was very cautious in placing so-called granitic pegmatites among his group of giant deposits. Only some of the most exoticpegmatite deposits related to alkaline intrusions, greisens and skarns were among the listed of large deposit some of which even called “ giant” or “ super-giant” deposits (Lovozero, Russia, Ilimaussaq, Greenland, Shizhuyuan, China, Nui Phao - Tam Dao District, Vietnam, Letitia Lake-Two Tom deposit, Canada, Zholtye Vody, Ukraine ( Vlasov et al., 1959; Miller, 1988; Tarkhanov, 1991; Lu et al., 2003; Meinert et al., 2005 )). According to Laznicka's ranking (2014) these deposits may be described as follows: “Giant (and super-giant) metallic deposits are de�ned as those that store the trace m etal (and some major metal like Fe, Al) equivalent in 1011 (10 12) t of continental crust in Clarke (mean crust content) concentration”. The classical pegmatites and aplites cannot be attributed to the so-calledgiant deposits,althoughthey play a significant role in the supply of rare metals, as shown in the succeeding paragraphs. There is a wealth of books and papers dealing with the geoscienti�c issues of rare element pegmatites, mainly mineralogical in essence, whereas the number of studies about feldspar, quartz and mica is comparatively small. The latter rock-forming minerals make up the lion share of pegmatitic rocks and thus are mined all across the world. Attempts to obtain reliable production � gures for the colored gemstones exploited from pegmatites, often fail, while the number of papers is almost as big and multifaceted as for the group of rare element pegmatites. Gemstones are high-unit value commodities, and if you have a bonanza of the right gemstone for the market you will make a fortune with a pocket full of mineral grains and not communicate site and output immediately to the public. So economic data will hardly appear in any state of �cial statistics or reports, and if at all, � ltered so as to do not spoil the ongoing mining and trading activities. For a general overview of the various commodities the reader is referred to the “Chessboard classi�cation scheme of mineral deposits” where in the section “ supply and use ” one can obtain updated information through a link to the US Geological Survey Data Base for those commodities that did not by-pass the of �cial statistics. In the following sections only the pegmatitic fraction of the commodities is distilled out of the database as far as it is possible, taking into consideration what has been stated previously for the high-unit value commodities. As far as the processing of rare-element pegmatite ore is concerned basic information can be found in the English translation of a Russian book by Zelikman et al. (1966). A general scheme of processing is given for each commodity but it would go far beyond the current review of pegmatites and aplites to illuminate the present state of unpublished innovation in industry of this subject matter. It will be of little advantage either to know that the addition of a certain dose of a � otation agent improves the recovery of a special commodity in a particular case but has no meaning for the rest of the deposits under consideration, a fact especially true for the r ather extraordinary pegmatite deposits. To keep pace on reasonable level, the reader is referred to publications such as “Mineral Processing and Extractive Metallurgy ” (Maney Publishing). 7.1. Tin–tungsten 7.1.1. Tin

The average grade of tin in the earth's c rust stands at 35 ppm Sn. Today Sn is used for tin plates, various alloys (bronzes, brass), solder, babitt, in the glass and ceramic industry, for electronic devices

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(LCD displays) andpigment. In hard rock deposits Sn maybe feasible for mining at a grade of greater than 0.3% Sn, in placer deposits it is feasible even below that level as price-enhancing elements may show up as by-product and the accessibility of the ore shoots is much better than in a hard rock deposit (N 0.01% Sn). Many trace elements may decrease the value of Sn concentrate if presentat too elevated a level (Fe N 5%, S N 1%, Pb N 1, As N 1, Cu N 0.5% Bi, Sb, W, S). Gravity sorting and magnetic separation are normally used to enrich cassiterite, which does not cause any bother as being associated with Ta-enriched COLTAN minerals (pers. com. H. Wotruba). Grain size may sometimes be an obstacle for the use of cassiterite since ore particles of less than 0.04 mm are hard to process. Cassiterite, and to a lesser extent stannite are operated from a wide range of deposits involving hydrothermal vein-type, subvolcanic deposits, VHMS deposits, skarn and placer deposits. Only a smaller fraction is derived from the deposits under consideration in this review. Therefore some countries which have also been dealt with in this book as reference types for rare element pegmatite containing the metal under consideration are treated as an example for the economyoftininpegmatites.Ithastobenotedthatthisisonlyanapproximation, especially in those countries where artisanal mining or small-scale operations are widespread. The main producer is China, followed by Indonesia, Peru, Bolivia, Brazil and DR Congo. Among the top scorer, there are countries such as Bolivia that produce from deposits different from pegmatites. The production for Sn and W has been given for the DR Congo where a great deal of the commodities under consideration has been derived from pegmatites (Fig. 42). The mining data of Sn and W are plotted side-byside with COLTAN. All data have been collected from the USGS Database. Sainsbury (1969) reported for the Manono–Kitolo pegmatite 0.9 Mtof Sn metal. The largest hard rock Sn deposit with disseminated cassiterite in subvolcanic intrusions and veins at Llallagua, Bolivia, contains 2 Mt metals (Laznicka, 2014). 7.1.2. Tungsten

Tungsten is less widespread than its “closest chemical ally” tin in the crust andonlyattains1 ppm W. Wolframite andscheelite is minedat an ore grade of 0.2 to 0.4% WO3. Contents of Au, Ag, Sc, Nb, and Ta increase the value of W ore. Tin N 1.5%, As N 0.2%, P N 0.03, S N 0.3%Sb,Pb, Cu, and Mo when present in high amounts may be detrimental to the quality of theore. Tungsten is used fortungsten carbide to harden alloys (WIDIA), ferrotungsten, stainless steel/high-grade steel and tungsten � laments for lamps and thermionic applications. Secondary W originates from recycling of steel alloyed with W and powder-metallurgical material such as W carbide which is mainly used in heavy-duty tools e.g., drill bits. The major producers by country are China, Peru, den USA, Korea, Bolivia, Russia, Austria, Portugal, Ruanda and the DR. Congo. Only the three countries at the bottom of this sequence produce form deposits referred to in this review. China holds a top position with approx. 80% of the global W production. In Fig. 42 Sn and W are plotted side-byside to allow for a comparison of the development of mining Sn and W from similar deposits. Both diagrams are similar in shape, but W reached its maximumone year earlier than Sn.Gravitysortingand magnetic separation are applied.Being associated with Ta-enriched COLTAN mineral separation can be fraught with dif �culties, whereas being associated with cassiterite theseparation is feasible(pers. com.H. Wotruba). 7.2. Beryllium

Beryllium contents average 3 ppm Be in the earth's crust. Beryllium belongs to a group of elements in pegmatites whose minerals are used to recover the metal beryllium from and in combination with special chromophoresmay leadto gemstones of jeweler's quality, suchas aquamarine, chrysoberyl/alexandrite or emerald. Chromium and vanadium give emeralds their distinctive green color. Cr 2O5 contents of 0.2 to 1.5% and V 2O5 contents of 0.1 to 1% with 0.2 to 1.8% FeO are required

foremeralds. At an oregrade of 0.2 to 3% BeO, Be mineralization become economic, provided there exist reasonable resources. The USA, China, Mozambique, Madagascar and Portugal have the lion share in the production of beryllium, lying between 120 t and 1 t per annum. The major production is derived from the open pit operation in the TopazSpor Mountain region of Juab County, USA. Bertrandite developed by epithermal alteration of calcareous volcaniclastic rocks, where it is associated with adularia, � uorite, and smectite. Pegmatite was the major source of beryllium in the New England States where beryl was recovered as a by-product during mining of feldspar and mica. Madagascar has been taken reference to show besides each other the production of beryllium metal and beryllium in the most precious gemstone of this element group, emerald. Thepeaksin the production �gures of emerald give an impression as to the reliability of such data for colored gemstones which were produced and exported in a rather “ gray zone” (Fig. 43, Table 4). The major � eld of use is an indirect one of some of its minerals in gemology and jewelry (emerald, aquamarine, heliodor, goshenite, morganite, bixbite…). Beryllium metal � nds application in aerospace and defense due to its stiffness, lightweight and dimensional stability overa wide temperature range. Beryllium–copper alloys(CuBe, CuCoBe) are looked for owingto their electrical and thermal conductivity, high strength and hardness, good corrosion, fatigue resistance and nonmagnetic properties. Beryllium oxide is a good heat conductor, has high strength and hardness and performs well as an electrical insulator. The metal is also used in X-ray technique. Beryl is either hand-picked, especially when its esthetic value is the reason for mining it, or passed through an industrial bene�ciation processes, involving �ne-grinding, �otation,optical sorting, and NIR sorting (pers. comm. H. Wotruba). 7.3. Rare earth elements and zirconium

Today, the rare earth elements have gained a mysterious position outside the world of science and technology, due to the shortage of some of the REE, the trade dispute about this commodity with the major producer China and their close relation to a wide range of products in the “ green technology” and electronic industry. Fig. 44 leaves no doubt that some of these elements are of more widespread occurrence in the earth crust than many of those rare elements typical of pegmatites, dealt with in the previous Section 4. On the other hand the risk of supplyis not valid for the entiregroup of elements.It is the group of MREE neodymium, europium, terbium and dysprosium where supply–production de�cits exist. Even the HREE, considered as “ high-risk elements” come under increased pressure, as the production of HREE-saving LEDs grow faster than expected and the demand of yttrium, europium and terbium slumps (communication during a conference by D. Kingsnorth, 2014). Currently the economic situation gradually normalizes. REE end up in a wide range of � nal goods and various industrial branches.They are used for alloying light andbase metals (Ce), coloring of glasses andin nuclear technology. Lanthanum isotopes are applied as source of radiation and Eu and Y are used in special cathode-ray tubes (television). As to the reserve situation the “Big Three” are China, Brazil and the USA. Considering the mine production, China is far ahead of the USA, India, Australia andRussia.Considering the mine output as a function of the type of deposit carbonatite- and alkaline-intrusion-related deposits prevail among the primary deposits. Pegmatites may be present in some areas, e.g., Motzfeld or Ilímaussaq, but even if the future project are taken into account it will be the ion-absorptiontype and the vast supergene REE deposits which have a stronger say in the REE supply than the pegmatitic deposits. There are some projects closely linked to uranium deposits which are re-investigated currently for REE, such as Bokan Mountain, USA. Zirconium ore is used forthe recoveryof Zr andis also of importance for therecovery of Hf. Owingto itshigh refractoryqualities, approx. 70% of Zr is used forfoundry sand to make melting pots andrefractory stones


(zircon- andzirconium oxide stones). Apart from its chemicaland thermal stability it shows other qualities such as high thermal conductivity (N cooling rate) and being unwetted by molten metals. It is pH-neutral to slightly alkaline. These sands are used in steel-, glass and nonferrous metal production. About 20% of Zr is added to the raw material to manufacture glass, glazes, porcelain insulators and chemical porcelain. The rest is used for Zr metal and alloys in the nuclear industry and to produce special sorts of steel and getter (high vacuum pumps). Due to the special requirements as to the thermal stability, refractorygrade Zr must not contain free quartz, zircon grains should also be clear and free from cracks. For Zr metal and Zr–Ti alloys, the Hf content should be less than 0.02% and for the electrical industry less than 1.5% Hf. Mining Zr is feasible only when Zr contents exceed 3% Zr and con�ned to its placer deposits. A newsource hasbeen open up by thecompanyrunningthe Strange Lake pegmatite-hosted Zr deposit, Canada. The full-blown mine-output of the anticipated annual zirconia production from its Strange Lake REE deposit in northern Quebec is sold to New York-based TAM Ceramics Group, a leading manufacturer of zirconia chemical products (The Northern Miner Website, 2013). A comprehensive overview of the extraction of REE has been published by Gupta and Krishnamurthy (2004). Apart from the classical ways of gravity and � otation-based separation, there are two different complex pathways to follow-up, dependent upon the major minerals, the bastnaesite series on one side and monazite plus xenotime on the other side. The � rst group of minerals is treated by hot froth � otation technique with dissolution of calcite in the aftermaths by HCl. To obtain the pure REE, trivalent Ce is oxidized to tetravalent Ce and the remaining elements concentrated by liquid–liquid solvent extraction. Monazite and xenotime are released from the ore by decomposing it in an autoclave with NaOH at 150 °C. The cooled remains are washed with water to remove the soluble Na3PO4 and get rid of the Th in the residue. By a follow-up complex solvent extraction process the individual REE can be separated. Mixed-REEchloride is reduced to provide the “ Mischmetall”. To recover the individual elements, further reduction of the � uorides and sublimation will be necessary. The complex Strange Lake REE- and Zr-pegmatite deposit uses an acid bake at 220 °C for 1 h on the R EO-bearing granites and pegmatites resulting in the production of 77 –93% REO slurries. There is no need for further physical bene�ciation beyond initial crushing and grinding of the feed stocks, thus avoiding potential REO losses via early pre-concentration steps (source: http:// www.techmetalsresearch.com). 7.4. Uranium–thorium

The average grade of uranium in the earth's crust is 2 ppm U. Thorium is more widespread thanU and averages 6 ppm Th. The ore grade is highlydependent on the type of deposits and may godown to 100 ppm U in low-grade-large tonnage deposits. Grades greater than 1000 ppm are common to most typesof U deposits.Ca- andMg carbonates, sulfate, sul�de (N 0.5%) andin places Ca-phosphate may worsen the recovery of U in theprocessing plant. Apartfrom its usein thenuclearenergy industry there is little other use today. Uranium colors were used in the past. Depleted U may be used for ammunition. Thorium may � nd a much wider application outside its use as a nuclear energy resource for some alloys, glasses with high refractive indices and a source of neutrons. The biggest producer of uranium in 2013 was Kazakhstan (22,451), followed by Canada (9331), Australia (6350), Niger (4518) and Namibia (4323) (source: World Nuclear Association —tons per annum in brackets). In the majority of cases the top �ve recover uranium from unconformity-related, sandstone-hosted, hematite-brecciatype. In Namibia, apart from the calcrete U deposits, the Rössing U deposit is the major producer. It is a low-grade-large tonnage deposit

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with U contents in the range 60 to 500 ppm U (British Geological Survey). Extraction is aggravated due to the uranium bound to pyrochlore and refractory minerals. Rössing (Rio Tinto) had a mine output of 3449 t per year in 2008, accounting for 7.8% of the world production (British Geological Survey). The uranium concentration at Rössing, Namibia, has been discussed at length in the genetic part of the review (Section 4.4.2). Both radioactive elements U and Th are ranked in pegmatites mainly as value-decreasing elements when intergrown with W, Sn, Nb, Ta or Zr. As there is only one world-class operation of this type of uranium deposit at Rössing, processing there can be taken as reference for a low-grade-large-tonnage deposit (source: mining technology.com). The run-of-mine U ore is transported from the primary crusher to a coarse ore stockpile and further on comminuted to a grain size smaller than 19 mm. Subsequently a rod mill does the �nal job and crushes the ore downto mud particlesize.Thismechanical decomposition is followed up by leaching and oxidation with ferric sulfate and the pulped ore dissolved in sulfuric acid. The slimes are washed so as to obtain a clear uranium-bearing solution. A continuous ion exchangeprocess results in theuranium ions to getabsorbedfrom the solution. During the following two-stage solvent extraction the eluate is mixed with an organic solvent that takes the uranium-bearing component and then is mixed with ammonium sulfate solution. At the end, after precipitation of the yellow slurry and � ltration the yellow cake comes into existence after drying. 7.5. Fluorine–boron 7.5.1. Fluorine

Fluorine and the basic chemical compound hydro �uoric acid are produced from �uorite which is found, locally, in pegmatites, developing nice crystals but not concentrated to ore grade there. Primary deposits of acid, ceramic or metallurgical grade �uorite are located outside pegmatites (Dill, 2010). Cryolite important in the Al production (Hall –Heroult Process), can be recovered from pegmatitic ore, but the mostwell-known occurrence of its kindIvigtut, Greenland, is exhausted now. Moreover pegmatites are a target area for colored gemstones containing � uorine, particularly in topaz which is the leading member of this group (Table 7a, Fig. 18). 7.5.2. Boron

From the economic point of view, boron is not very much different from �uorine with respect to the pegmatitic deposits. The deposits where boron is recovered from are abundant in borate of (volcano)sedimentary origin and located mainly in Turkey one of the leading producers of this commodity. A different view can be offered for gemstones accommodating boron in their lattice. Tourmaline-group minerals are among the most looked-for colored gemstones containing boron and known to be concentrated in its best quality in pegmatites (Tables 6, 7b, Figs. 18b, 43). The “ rising star” among these tourmaline s.s.s. is the Cu-bearing blue “Paraiba Tourmaline” which can fetch a high price on the market and has been found in its best quality in four deposits Batalha, Qunitos, Clorious and Capoeira mines of the Borborema Pegmatite Province, Brazil (Beurlen et al., 2011) (Fig. 17c). A similar tourmaline resembling the Paraiba tourmaline from the type locality was discovered in pegmatites at Mavuco in the Nampula Province, Mozambique. From 2004 to 2008 the annual production of tourmaline in Brazil was 80,000 kg, compared with 50,000 kg of topaz (USGS database 2009). As both elements are targeted upon in pegmatites for the esthetic value of their host minerals topaz and tourmaline, respectively, industrial methods of mineral processing other than the classical wet techniques used for the concentration of heavy minerals need not be discussed here.

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7.6. Phosphorus

The economic situation depicted in the previous Section 7.5 for �uorine and boron with respect to pegmatites as a source of both el-

ements, applies even more for phosphate. The lion share of phosphate, with apatite s.s.s as the major host, has been derived from sedimentary phosphorite deposits (Dill and Kantor, 1997). Pegmatites may have a more diverse phosphate mineralogy than sedimentary phosphorites but they are no match to the phosphorite deposits as to size and grade. Phosphate minerals, albeit not rated as high as aquamarine or emerald among gemologists for their softness and ubiquitousness, may arouse attention, especially for their exceptional colors like the green apatite from Spain called asparagus stone, the variety trilliumite from Ontario, Canada or the blue-green apatite, closely resembling the costly tourmaline from Paraiba, Brazil. Suspending the aforementioned hydrated Li-, Cu- andBe phosphates from the present discussion of gem-quality phosphates, it is mainly the lazulite –scorzalite s.s.s, brazilianite and phosphophyllite which may attract notice especially among lapidaries. Production � gures are hard to publish for these phosphate-bearing gemstones as they are not listed country-wise in the statistics. Like � uorine and boron, phosphate is recovered economically from deposits, different from pegmatites. Only the Li phosphates of the amblygonite-montebrasite s.s.s. were mined and used for the production of Li carbonate and Li �uoride in Brazil (see next Section 7.7). 7.7. Lithium–cesium–rubidium

Spodumene (8.03% Li2O), lepidolite (7.7% Li 2O), zinnwaldite (3.4% Li2O), petalite (4.5% Li 2O) and amblygonite (7.4% Li 2O) are the most looked-for minerals to recover Li. Concentrations exceeding 0.5% Li 2O arefeasible. Lithium is used forlight metal alloys,as a �ux in theceramic industry and Al plants, a lubricant additive in chemical processes, for batteries, solder, rocket propellants, catalysts during production of rubber and in the nuclear industry and medicine. Substitution of Li by Ca, Mg and Zn is common. Cesium plays a vital role in GPS technique, Internet and cellular telephone transmissions, and aircraft guidance systems. Cesium clocks are well-known for their accuracy and the cesium atomic clock is used for the international de�nition of a second based on the cesium atom. Radioactive cesium is used to treat cancer. The alkaline element is widely used in industrial gauges, in mining and geophysical instruments. It plays an important part to sterilize food, sewage, and surgical equipment. Cesium is also used in ferrous and non-ferrous metallurgy. Applications for rubidium-bearing compounds are known from biomedical research, electronics, and pyrotechnics. The element also sees application in photocells (solar panels, motion sensor devices). Similar to cesium it is also found in some atomic clocks, being an essential part of global positioning systems (GPS). Lithium, cesium and rubidium are recovered from siliceous and from the phosphatic types of Li ore in pegmatite deposits. However, it is a highly competitive market, with two types of deposits challenging each other. Kesler et al. (2012) emphasized this issue in their monograph on “Global lithium resources ”. The average brine deposit (1.45Mt Li) is more than an order of magnitude larger than the average pegmatite deposit (0.11 Mt Li) and brine deposits, especially those from the large Atacama (Chile) and Uyuni (Bolivia) deposits, have a much larger total lithium resource (21.6 Mt Li) than the hard rock deposits. Brine deposits clearly have a much greater capacity for large-scale, long-term production than do pegmatite deposits. The Cinovec–Zinnwald deposit (Germany/Czech Republic) classi � ed as a large deposit by Laznicka (2014) contains Li in zinnwaldite together with Sn, Rb, and Cs amounting to 1.43 Mt of Li metal at a grade of 0.25% Li ( Štemprok et al., 1995). The grade

should be above 0.5 wt.% Li 2O. At Greenbushes, Australia, the largest producer of lithium from hard rocks, the resources are estimated to be 70.4 Mt of Li 2O at 2.6% Li, while its reserves stand at 31 Mt of Li2O at 3.1% Li (www.talisonlithium.com). This does not sound good but it shows a trend from high-grade towards low-gradelarge tonnage deposits. Cesium and rubidium are found in both types of deposits. Mineral processing is done for petalite and Li mica ore by means of �ne grinding, � otation, manual sorting, optical sorting, or NIR sorting (pers. com. H. Wotruba).At Greenbushes,Australia,a mill on site grinds the spodumene prior to undergoing gravity and magnetic separation (www.talisonlithium.com). 7.8. Niobium–tantalum–scandium

While lithium, cesium and rubidium face a strong challenge from a varied spectrum of sediment-hosted lithium deposits, pegmatitic and sedimentary niobium and tantalum deposits complement each other ideally. Columbite and pyrochlore need to be upgraded in excess of 0.5% Nb–Ta oxide in hard rock deposits and 200 g/m 3 Nb–Ta oxide in placer deposits where they show up as heavy minerals in the alluvial and �uvial drainage systems around the parental pegmatites. Rare earth elements and scandium increase the value of the Nb –Ta ore, whereas P N 0.1%, Ti, Zr, and Sn (total amount should be b 4 to 8%) have a negative effect on the ore assessment. It is used for stainless steel/high-grade steel, Nb carbide, high-temperature alloys and within the nuclear fuel circle (atomic reactor). World resources of niobium are more than adequate to supply projected demand. There is one challenge to the pegmatite-hosted niobium by the much larger resources of niobium as pyrochlore in carbonatites across the world. Brazil and Canada are the leading producers of this rare metal. The �nal use of Ta slightly deviates from that of Nb in that it is also used for catalysts, electrolyte condensers, cathodes, spinning nozzle and in medical technique (implants and instruments). Substitution of Ta is carried outby Nb, Al, ceramics, Pt, Ti, Zr forsome goods, but limited recycling. The known resources of tantalum, most of which are in Australia and Brazil, are adequate to meet the demand. The mine production for 2013 (USGS database) lists Rwanda slight ahead of Brazil followed by the DR Congo. Nigeria, Canada, Mozambique and Burundi are trailing behind them by a considerable margin. In Fig. 42 the Nb and Ta mine output has been compared with the output of the classical elements Sn and W from the pegmatites. The new technology forces to intensify the mining of the Nb and Ta, whereas the accompanying elements go down. Mineral processing of COLTAN is attractive in pegmatites if tantalum is concentrated well above the level of niobium (concentrate N 30% Ta2O5). The radiation of the ore should be of low level. That is, why microlite being enriched in Ta, too often strongly contaminated with U and Th does not sell on the market (pers. comm. Wotruba). Niobium and tantalum pyrochlore ore is processed using �otation and magnetic separation, while columbite and tantalite are bene �ciated by magnetic, electrostatic and gravity methods used to be applied to heavy mineral concentrates so as to obtain a concentrate of 60% Nb –Ta pentoxide (Fig. 48). Scandium �nds little industrial application except in nuclear technology, the production of lighting devices and laser crystalrods. Scandium is mainlyproduced as a byproduct during processing of various ores or recovered from tailings and residues. Like its associates, mentioned previously, the resources of scandium are abundant to satisfy projected demand. For all three rare elements the geogenic setting across the globe should not render us to panic. Similar to other mineral commodities such as diamonds attempts have been made to bar illegal trading of COLTAN by building up a highly sophisticated chemical testsystem. I castsome doubt on the workability


of these methods outside thelaboratoryand I fear of being only balm for the politicians' soul. 7.9. Arsenic –bismuth– zinc –molybdenum

None of these elements re ferred to mainly for genetic reasons in Section 4.9 is concentrated to such a level to compete with other mines working porphyry copper deposits, subvolcanic or SMS and VMS deposits, so that we are not in need of a detailed economic treatment of them in context with pegmatites. Only as a byproduct bismuth and molybdenum are recovered along with other commodities as shown by Galliski (2009). During a period of mining lasting for 80 years, the Pampean Pegmatite Province, Argentina, produced in excess of 1 Mt of feldspar of ceramic grade, 1 Mt of quartz, 50,000 t of mica, 25,000 t of beryl, 10,000 t of spodumene, 45 t of tantalum minerals, and only 10 t of bismuth minerals. Of this quartet of elements only bismuth and molybdenum deserve further treatment as to their bene�ciation to achieve a saleable concentrate. Bismuth should grade between 0.1 and 1% Bi to be recovered for a pro�t from the pegmatites. It is mainly done by gravity sorting and �otation. This is true also for molybdenum, whose ore is subjected to �ne grinding to a particle size of less than 100 mm after that undergoes �otation (pers. comm. H. Wotruba). The grade should be between 0.2 and 1% Mo at the lowest level. 7.10. Feldspar

Only a small fraction of the feldspar quarried in pegmatites is used for ornamental or dimension stones (Fig. 19b). For gemological products pegmatites may be a bit more attractive but certainly come close to what has been mentioned for tourmaline and beryl, including its multicolored varieties. The majority of feldspar is used as �ller in plastics, paint, sealants, adhesives, abrasives, � ame damper in the match industry, cosmetics, � berglass insulation, welding rods and especially for ceramics (porcelain) and glass. The sodium and potash feldspar won from pegmatites may see some different applications. Feldspar powders (10 –15% alkali (K 2O + Na 2O)) melt at medium to high temperatures and used as a � ux yielding a good glaze (ceramic feldspar N 9% K 2O, glazes N 4% Na 2O). Potash feldspars are used in bodies where they promote nitri�cation. Sodium feldspars in glazes used mainly as a source of alkalis. No other raw material comes closer to being a complete glaze on its own than feldspar. Identi�ed resources of feldspar are large enough to meet the world demand. Pegmatites have to compete with feldspar arkoses and altered granites where open pit mining and the friability of the rocks under operation give its competitors an edge over hardrock deposits like feldspar pegmatite (Fig. 45a, b, c, d). A comparison of the different photographs in Fig. 45 underscores why underground operations on feldspar are placed on a disadvantage in some cases as highquality competitors are close-by. Considering the mine output, Turkey lies ahead of Italy and China. The reserves of Brazil are estimated to be higher than those of Turkey but for a number of countries the true reserves cannot be listed. 7.11. Quartz

glass andelectronic-grade material. Thisholds truealso for semiconductorsand ferrosilica and chromiumsilicacompounds. Only a few deposits of vein quartz in the world can meet with these demands so that �awless quartz from natural occurrences are outnumbered by cultured quartz being produced synthetically from rock crystals of inferior quality (“lascas”). For siliceous semiprecious-gemstones, the “Four Cs” do not have the same importance as for diamonds. It is � rst and foremost the color, splendor and size that matter or the habit and crystal shape, if the silica minerals amethyst or smoky quartz are picked out of the pegmatites to end up in the showroom (Fig. 32e, Table 11b). Feldspar and quartz are the major components of the pegmatitic rocks and treated in this section together. Their bene�ciation covers the entire spectrum from hand-picking done by trained technicians being alongside the conveyor belt to technical methods also mentioned above for the concentration of rare metals. It encompasses selective �otation, different types of wet and dry high-power magnetic separation and electrostatic separation ( Jakobs and Dobias, 1991; Jakobs, 1996; Dorfner et al., 2000; Jakobs and Sherrell, 2008). In addition to the separation of the two major components and cleaning from phyllosilicates, the grinding and sieving is an important task to provide tailor-mode � nal products for the ceramic industry. For the grain size in the range 20 to 100 μ m ball mills with air separator are applied. To prevent contamination with h eavy metals and guarantee Fe-free milling aluminum oxide or silex areused (Max Schmidt Silbergrube Waidhaus, Germany). A centrifugal grinder in combination with a special sieving system is used for the grain size range 100 μ m through 1 mm. Amberger Kaolinwerke (AKW) sold three different classes of products from their Hagendorf deposit named “Spezial”, “H” and “I” which are arranged in decreasing order of purity grade: “Spezial”:

K feldspar 69%, Na feldspar 25% Quartz 6% Fe content 0.05% K feldspar 68%, Na feldspar 24% Quartz 8% Fe content 0.10% “H”: K feldspar 67%, Na feldspar 23% Quartz 10% Fe content 0.18%. “I”: For both commodities the resources are large as far as the ceramic �nal products are concerned. For high-purity and ultrahigh-purity quartz theresources are less widespreadand a great deal of quartz crystals, especially for the electronic industry is based on cultured rather than natural products (Dolley, 2011). 7.12. Feldspathoid

Feldspathoids almost exclusively are usedfor their esthetic value, eitheras single crystals or within the hostrock. Sodalite, hauyne, scapolite and “ lapis lazuli” are, locally, of gem-quality, inferior qualities may be looked for by collectors. Many of the blue speckled syenitic rocks are quarried as dimension stones (Fig. 33). Only nepheline syenite and syenite pegmatites are usedfor ceramic products, �ller and glass in Canada, Norway and Russia (Potter, 2007). 7.13. Alumosilicate and corundum

The three polymorphs of alumosilicates are used in the industry in order to produce refractory materialaccording to the following reaction 3(Al2O3·SiO2) 3 Al2O3·2SiO2 +SiO2. At temperature between1350° and 1550° kyanite, andalusite and sillimanite turn into mullite and quartz along with an increase in volume. As an alternative to bauxite neither alumosilicates nor corundum from pegmatites are currently used due to the limited size of the deposits. Opaque corundum is used as abrasives but often eclipsed by colored varieties of precious corundum from different countries. Corundum-bearing pegmatites (mainly the so-called desilici�ed types) and associated skarns are known from many countries such as Vietnam andMadagascar. Dueto its density, corundum is also worked in thealluvial–�uvialplacer depositsof the clastic apron around these primary pegmatite deposits or found in eluvial ⇒

Quality requirements for silica are very different and as with many raw materials, they are a function of the � nal use. Compilations by Harben and Kužvart (1996) reveal what mining engineers and geologists have to pay attention to, as they explore and exploit rawmaterials used in the production of glass, ceramics, refractories, chemicals, �llers and extender or in metallurgy, as blasting, � lter and propant sands. In addition to high SiO 2 contents, it is the whiteness, hardness, inertness low concentration or absence of deleterious trace elements (Fe, P, S, Pb, Zn, As, Sb, B, Cd, V). High-purity and ultra-high quartz reaching almost 100% SiO2 are required for the production of silica glass, optical

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and residual placers on top of the primary deposits, which used to contain the better � awless gemmy quality, whereas the primary deposits are abundant in showcase-quality precious corundum that attract the attention of mineral collectors. Corundum offers a good example for a dualuse. Thehigh-quality types of precious corundum aresold across the counter of a jeweler, the showcase-quality attracts the attention mineral dealer and collector and the inferior quality and opaque material can still be used as an abrasive. Considering the export � gures it is dif �cult to decide how much of them h as to be attributed to the various types of mineral deposits, including primary and secondary deposits in and around pegmatites, but it may give the reader an impression of the economic importance of corundum varieties for Madagascar and Sri Lanka. Madagascar produced an estimated 50% of world sapphire output mainly from Ilakaka and Sakara mines; ruby is exploited at Andilamena and Vatomandry. From 1998 to 2002, exports of rough sapphire increased to 9326 kilograms (kg) from 2547 kg; ruby, to 889 kg from 30 kg. In 2003 a new deposit was discovered at Monombo Voavoa, which is located 38 km west of Ilakaka. Small amounts of sapphire were produced at Amboasary, Andrebabe, and Fenerive Est in north-central Madagascar and at an alluvial deposit in the Manatenina area near the southeastern coast (Yager, 2003). Another country which jewelers have a keen eye on is Sri Lanka (Kuo, 2005). Gemstone mining activity in Sri Lanka increased slightly in 2005. The Bagawanthalawa gemstone deposits are among the richest sources of blue, orange-yellow, and yellow sapphires and alexandrite and chrysoberyl cat's eye. The Elahera gem � eld currently provides approximately 35% of the gemstones exported from Sri Lanka mainly gem-quality sapphire, spinel, garnet, chrysoberyl, zircon and tourmaline. Apart from the aforementioned countries, precious corundum is also mined in Afghanistan, Brazil, and Burma (Myanmar) in small-scale mining operations, often in remote regions with little information on the production � gures. According to the US Geological Service Database the value of production of natural gemstones other than diamond was estimated globally to be more than $2.5 billion in 2012. Precious corundum is manually separated or in case of pervasive weathering won by hydraulic mining, washing the gemstones out of the argillaceous matrix. 7.14. Garnet

Around 80% of garnet, mainly almandine followed by pyrope, is used as industrial garnet for sand blasting, water � ltration, water jet cutting, coated abrasives and polishing. Almandine is sometimes given local trade names such as “ Oberpfaelzer Schmirgel” (emery from Upper Palatinate, Germany) referring to the mining site which is a saprolite overlying metasedimentary rocks as well as to its preferred use for polishing glassware. Its subhedral to euhedral shape in placer and crushed garnet resources, its low contents of heavy metals and its high resistance to abrasion and chemical agents which make garnet an ideal placer mineral in nature are also excellent characteristics for various industrial applications. In places, these garnet varieties also occur in pegmatoids and metapegmatites (Fig. 36). Garnet (grossularite-dominated) may occur in pegmatiteskarn (Fig. 36e, f) or in the marginal parts of pegmatites and pegmatoids (Fig. 36d). The latter often has spessartite prevailing over almandine and pyrope and stands out by its pinkish to red mineral color. They may reach showcase but seldom jeweler's quality. It is dif �cult to give reliable �gure for garnet derived from the exploitation of pegmatites. Well-shaped and -colored garnet, enriched in spessartite is expected to have derived from pegmatites, whereas the majority of industrial garnet has been mined from metamorphic rocks.If recoveredfrom felsicrocks,owingto itshigher speci�c gravity than feldspar and quartz, wet and dry methods normally applied in heavy minerals separation are suitable for creating pure garnet concentrates.

7.15. Mica

Mica often attains a large crystal size in pegmatites, so that it can even be separated manually as a by-product from feldspar –quartz pegmatites, pegmatoids and metapegmatites. It is prevalently muscovite and the Mg-enriched end member of the biotite s.s.s., phlogopite, both of which mark the crustal or subcrustal origin of pegmatites. Muscovite and phlogopite are used, because they are chemically inert, dielectric, elastic, insulating and lightweight, only to record a few of their characteristics which make them of interest to a wide range of applications. Phlogopite has an edge over muscovite in all applications in which a combination of the above characteristics with a high temperature-stability is required but is rarely observed in pegmatitic rocks and mainly bound to carbonatites and ultrabasic igneous rocks. Mica � nds an outlet in sealants, resins, adhesives, tires, greases, lubricants, insulators, ceramics, automobile parts such as brakes, in the oil industry, and welding rods. The micaceous products are subdivided into two principal classes, according to their size and thickness as well as structural defects and denominated as high-quality “ sheet mica” or as low-quality “ ground mica”, which derives as a by-product from processing of run-offmine ore of feldspar and quartz pegmatites. Ground muscovite is mined from pegmatites in the USA and Brazil, whereas India is the leading country for “ sheet mica”, mainly muscovite from unzoned and zoned mica–quartz–feldspar pegmatites that have been intruded into Achaean gneisses (Skow, 1962). In the USA, by the beginning of the last century, the New England States were the leading producer of mica, mined from pegmatites mainlyin metasedimentaryrocks. Other countries producing sheet mica from pegmatites are Braziland Madagascar. Scrap or ground mica is available to meet with the demands in the future, while for sheet mica precise prognosis cannot be given based upon the US GS Database. Mica plates larger than 10 cm2 can be sorted and separated by hand from the pegmatitic ore. 7.16. Graphite

Commercial graphite is traded as graphite � akes. They are � at, plate-like with an average size of 0.25 cm. High-crystalline ( “lump or vein-type”) graphite lumps of high crystallinity derive from veins and “ amorphous” graphite whose tiny crystals are only visible under the microscope derive from mainly thermally metamorphosed coal seams. Pegmatites are involved in the graphite deposits in Sri Lanka from which the lump and chippy dust varieties have been derived. Crystalline graphite in pegmatite deposits should be enriched at a level exceeding 22 –35% C. After crushing and milling the graphite ore which isdonein a water slurry, the �ne-grained material is passed into the froth � oatation cells. 7.17. Kaolin

High-quality Fe-free kaolin is a widely looked-for raw material in manufacturing porcelain. Apart from ceramic goods (wall and �oor tiles, china ware, sanitary ceramics), kaolin is also used as �ller, paper coating or the production of refractories (chamotte, bonding clays). Residual kaolin evolving on pegmatites is known from the, e.g., Spruce Pine District in the USA and the Borborema District, Brazil ( Fig. 39a). The main source of kaolin lies within residual kaolin deposit on parent rocks different from pegmatite. The bene�ciation of kaolin has much in common with what has been recorded for quartz and feldspar in pegmatite ore. The processing deviates from the common family tree of processes as the � ne grain size of kaolin takes effect. The kaolin is washed from the value-decreasing gangue and passed several times through hydrocyclones to achieve the quality required by the client. The water is removed from the kaolin slurry hydraulic-mechanically and later


on dried resulting in a � ne kaolin powder to be transported in bigpacks to the client. 8. Structural geology of pegmatites

Studies about the structural geology of pegmatites are rare compared with the wealth of publications available on the petrography and mineralogy of pegmatites, including the experimental studies. Descriptions of the internal zonation are common and used to be referred to in context with the mineralogical studies of the different mineral assemblages. Therefore only some few examples are presented here, directly related to the case studies in Section 4. 8.1. Pegmatites and the architectural elements of the country rocks

Based upon the monographic studies of Grif � tts et al. (1953) and Grif � tts and Olson (1953a, b) a block diagram has been designed for the various morphological types of pegmatites in relation to the crystalline basement rocks of the south-eastern Appalachian Mountains, USA (Fig. 46a). The pegmatites were emplaced along the limbs of the anticlines and synclines as coherent tabular or lens-shaped pegmatites. Pinching and swelling in these tabular pegmatites eventually leads to a boudinage of the limb-hosted pegmatite bodies and ends up in individual lenses along with the stress –strain relations along the limbs (Fig. 24e). The size of the pegmatites used to increase in the hinge zone of the folded crystalline schists, which are made up of mica- and hornblende schists (Fig. 4n). Apart from these fold-related pegmatite deposits another set of late-stage sheet-like pegmatite dikes cut through the metamorphic rocks, displacing the fold-related as well as older fault-related pegmatite dikes. Similar fold-related sets of pegmatites may be found elsewhere, e.g., in NE Bavaria, Germany, where stocks reside within the hinge zone of major anticlines and parasite folds and tabular pegmatite evolved along the limbs of anticlines. Suf �cient accommodation space was provided in the hinge areas and reduced room left only for the tabular pegmatites along the limbs of late Variscan anticlinal structures. Both types follow the rules of mimic tectonics, owing to the late synto posttectonic emplacement of the pegmatites. Faults crosscutting the folded basement rocks and their pegmatites are mineralized with pegmatitic and aplitic dikes and quartz dikes. According to the deformation pattern, common to the quartz dikes/quartz pegmatites and quartz–feldspar pegmatites dikes, both mineralizations are paragenetic with only compositional differences between the two. It is not unusual to �nd mineral assemblages in the central zone of the pegmatites again as faultbound mineralization in the external zone of the pegmatites as a consequence of kinematic variation. In the Kings Mountains Region in North Carolina, USA, Sn–Li pegmatitestabular(spodumene) occur andshowin themap lens-shaped but a slightly distorted morphology (Fig. 46b, c). The micaschists surrounding the granites are cut through by several shear zones which acted as controlling planar architectural elements for the emplacement of the Mississippian (360 to 325 Ma) spodumene-bearing pegmatites (Horton, 1981) (Fig. 46b, c). The pegmatites omit the metacarbonates and only sporadically show up in the endocontact zone of the granites, attesting to a younger shearing of the micaschists and a later emplacement of the pegmatites than the intrusion of the granite. Keeping off the metacarbonates is due to the different rock competence and rock strength. Metaargillic rocks are more susceptible to thrusting and shearing than massive metalimestones. This type of mineralization has also a structural counterpart in the Variscides across the Atlantic Ocean along the western edge of the Bohemian Massif. It is the thrust plain-related part of the Sn–Li mineralization which in this case changes from Li pegmatite (Li phosphate) to a Li–Sn granite pegmatite (Li mica) instead of a Li –Sn pegmatite (spodumene) in the US reference area. Contrasting physical conditions are held to be

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responsible for the different composition while the structuralregime is similar in both ensialic orogens during the waning stages of the Variscan/Alleghanian Orogeny. The US part is more thrustbound while the German and the Cornubian part (see next paragraph) is more collisional-related. In his map produced for the Hyatt Region in the Crystal Mountain District, Thursten (1955) showed a similar tectonic scenario as illustrated in a more ideal scheme in the block diagram of Fig. 46a (Fig. 46b, c). In the Front Range of the Rocky Mountains Precambrian metasedimentary rocks, lithological present as quartzites, muscovite– biotite schists and biotite –sillimanite schists numerous irregularlyshaped pegmatites are exposed. They run parallel to granitic dikes and intersect biotite granites preserving a similar structural pattern which they follow outside the granite. It is a common view often seen in pegmatite districts, that granitic and pegmatites follow the same genetic blueprint and give rise to a set of concordant felsic mobilizates. The activity of pegmatites lasts longer and theyare undoubtedlyyounger than the granites, showing up again in a set of late-stage cross-cutting pegmatite veins. From the chemical point of view it is a s eries of zoned Bquartz–Na feldspar–K feldspar pegmatites (tourmaline). Among the rare elements Li, Nb, Ta, Bi, U and Be prevail. Lithium seems to be the most signi�cant element whereas Be comes as last in the row. As no quanti �cation can be done for the entire district for these elements and industrial minerals are paramount, they are not used here for classi�cation. Even in this case a comparison with some of the pegmatites along the western edge of the Bohemian Massif, Central Europe, is possible andforces us to think of a crustal-derived pegmatite system which was, in places, in�uenced by subcrustal processes — see discussion of individual elements in Section 4. 8.2. Plutonic pegmatites and the architectural elements of their country rocks

A detailed investigation of the structural geology and ore mineralization of granite pegmatites was carried out in the Cornubian Ore �eld, Great Britain (Section 4.1.1). The granite-related Sn–W mineralization in SW Cornwall, was emplaced very late during the Variscan orogeny at the transition from the orogenic collapse to the extension, in the wake of the Variscan collision ( Chesley et al., 1993). Exhumation and uplift brought the rocks into the brittle zone and folding and thrusting waned while brittle shear zones and extensional faults became more prominent (LeBoutillier, 2002). The emplacement of the Late Variscan granites occurred in a pull-apart-setting, accompanied by strike-slip faults. The Sn–W mineralization along the Variscan mountain chain from Portugalthrough the Erzgebirge/Krušne Hory Mts. (Germany–Czech Republic) took place in this rather shallow environment (Section 4.11). The Urucum Suite granitoids, southeastern Brazil, contains among others a pegmatitic facies that evolved in staurolite –garnet–muscovite –biotite schists. Detailed structural studies by Nalini et al. (2000) suggest that the Urucum Suite was emplaced during an important dextral strike-slip movement of the Brasiliano orogeny (650 to 450 Ma). The evolution from the peraluminous megafeldspar-facies granites to pegmatite-facies granites took place in a syn-collisional structural environment by partial melting of older intermediateto felsic crustal source rocks. 8.3. Pseudopegmatites andthe architectural elements of their country rocks

The Greenbushes pseudopegmatite was intruded as a series of linear dikes,varying from hundreds of meters to kilometers in length (Partington et al., 1995) (Fig. 47a).According to the authors, the pegmatite dikes and en echelon pods are clustered around an intrusive center located within a D2 high strain zone at the boundary between amphibolite and granofels units. The interpretatory cartoon added atop of Fig. 47a highlights where the maximum accommodation

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space has been created in the course of shearing and, consequently, the K-, Na- and Li zones were emplaced. Although the chemical and mineralogical compositions are different, in principal, pegmatites do not differ very much from shear veins giving host to base metal or gold ores and found across the globe in different setting running the gamut from deep syn-metamorphic through shallow unconformity related veins — see compilation for the Central European Variscides with references to individual examples in Dill et al. (2008b) as well as Dill (2015). The Greenbushes shear-zone hosted pseudopegmatite is kinematically equivalent to the fold-related metamorphogenic Ag-bearing Pb–Zn vein-type deposits Ramsbeck in the Rheinisches Schiefergebirge, Germany (Fig. 47b). Steep and � at-lying Pb – Zn veins are related to the folding of the Ramsbeck Quartzite in very-low grade metamorphic environment. Movements parallel the shear planes gave rise to the accommodation space for Pb–Zn accumulation (Fig. 47b). This thrustbound type-II base metal mineralization at shallow depth in a very-low grade metamorphic environment is kinematically analogous to the shear zone-hosted pseudopegmatite which formed under medium- to high-grade metamorphic conditions at depth — see also Section 6.3 about associated mineral deposits. Such a depth-related variation of kinematically analogous and chemical similar mineral deposits is known from many shear zone-related ore deposits. The most-striking example is the orogenic gold deposits forming a succession of ore deposits from Au –As deposits with skarns next to the intrusive rocks at approximately 20 km depth (e.g. Kolar) through to shear-zone hosted Hg–Sb deposits (e.g. New Almaden) at a depth of between 3 and 2 km. The recently investigated Whabouchi Li pegmatite, Quebec, Canada (2577 + 14 Ma) provides us with another example of a Li pegmatite synkinematically emplaced along a shear zone ( Bynoe, 2014). The pegmatite lies within a transpressional high-strain zone of a metamorphosed volcano-sedimentary belt. A subvertical transposition foliation and a subvertical stretching lineation are present in this zone. The main body of the Whabouchi pegmatite is parallel to the transposition foliation and branching veinlets from this body have been folded and boudinaged by shear zone deformation. The Whabouchi pegmatite is linked geochemically and geochronologically to a large pegmatite body yielding an age of 2595 + 14 Ma. The Whabouchi pegmatite was likely formed along with anatectic mobilization. The situation resembles to some extent the reactivated spodumene pegmatites in the Alpine Mountain Range which may be connected primarily to Paleozoic Li pegmatites in the Central European Variscides (Sections 4.7.1–4.7.2). AsfarasthecrustalderivationofrareelementssuchasLiinpegmatites is concerned some chemical investigation can be added to these considerations in structural geology (Cuney and Barbey, 2014). During granulite-facies metamorphism dominated by carbonic waves in a deep segment of the continental crust, these shear zones control, the percolation of F-, LILE-, rare metal-rich � uids liberated primarily by the breakdown of biotite; the enhancement of partial melting by F-rich � uids at intermediate crustal levels with the generation of F-, LILE-, rare metal-rich granitic melts; their transfer through the crust with protracted fractionation facilitated by their low viscosity due to high F –Li contents; and � nally their emplacement as rare metal intrusions at shallow crust levels. The side-by-side of granites enriched on one side and on, e.g., Li pegmatites on the other side, con �ned to shear zones � nds thereby support. 9. Genetic and economic conclusions and outlook

The present review of pegmatites and aplites is to be understood as a supplement in termsof genetic and applied economic geology to the numerous mineralogical and chemical studies, where often the three-dimensionally part of earth sciences is ignored for

whatever reasons. The most recent comprehensive petrologic publication on pegmatites shows the pegmatite mostly on a hand specimen scale or as an intergrowth of giant crystals added up with colorful cartoons depicting the models on how they are likely to have developed according to the author's ideas (London, 2014). There are countless cartoons and sketches designed by geoscientists to show the differentiation, internal zonation and mineralization. By contrast, not many possibilities are offered to consult in modern publications a longitudinal or cross section or a largescale geological map so as to get more information on the size and morphology of the pegmatite. Therefore some of the maps and cross sections were copied from the classical works done mainly in the USA by � eld geologists early during the last century (Fig. 46). An integration of aplites and pegmatites into the geodynamic setting is still missing at all and performed in the current study, using the elements, e.g., Nb, Ta, Li and minerals, e.g., nepheline, mica common to particular pegmatites and aplites as chemical and mineralogical links, respectively (Fig. 6). The chemical quali�ers (Sections 4.1 through 4.9) and the mineralogical quali�ers (Sections 4.10 through 4.17) of the CMS classi�cation scheme are the guidelines for the current study on pegmatitic rocks. It is to show that this simple and open access classi �cation scheme – Section 3.2 – can meet with the needs and wants of those taking a genetic approach (Section 4) when dealing with pegmatites as well as those economic geologists being directly involved in the extraction and processing of pegmatite-related commodities of high-unit value (gemstones) and of high-place value (feldspar) (Section 7). On principle,the proposedclassi�cation schemecan be takenas a secondsupplement to the “Chessboard classi�cation scheme of mineral deposits” (Dill, 2010). The �rst one of these supplements was prepared for gems and gemstones, placing emphasis on the distribution of gems and gemstones on the globeby country,by geology,and by geomorphology (Dill and Weber, 2013). Thereforeeach commodity (group) inSection 4 isaddedup withthe code used in the “Chessboard classi�cation scheme of mineral deposits” to ease a better correlation with other commodities that cannot be referred to in this text to avoid this paper of getting unfocused (Dill, 2010). It goes without saying that pegmatites are not a special type of stand-alone deposits as perhaps some might consider them, evolving independent from the rest of the “mineral kingdom” but theyare an integral part of the metamorphic and magmatic lithogenesis. Moreover these pegmatitic rocks are subjected to the rules of rock mechanics and structural geology as any other rock. It is hoped that by linking the pegmatitic deposit under consideration in a way like that with other ones an integration of the pegmatites into the overall metallogenesis can be achieved. It cannot be ignored that during this global review some of theitems essentialfor the CMSclassi�cation schemehad to be left blank upon categorizing the mineral deposits (Table 1). A new classi�cation scheme should not be build up on de �ciencies or a weak database, but uncover wherethede�ciencies are andwhere we have to �ll in theblanks.Geology of pegmatites is such a blank. For a �rst approximation the classi�cation used here may be suf �cient for a handling at an advanced level the database is currently still too weak. This is especially true for the symbol “S” in the classi�cation scheme, which means structure. Only a fewexamples were given inSection 8 to show where and how the tectonic setting of pegmatites has been investigated. Company reports, containing proprietary data, have not been considered in this assessment and therefore this point may be not up-to-date in all respects. There is a backlog in the 3-dimensional representation and structural geology of pegmatites that has increased in the last decades, because dealing with this subject matter is time-consuming. Understanding thestructural geology andthe morphology of pegmatite bodies in relation to the country and wall rocks is, however, a key element for a genetic and/or exploration model targeting upon pegmatite deposits.


9.1. Genetic conclusions

The ore body and the ore composition of pegmatites sensu lato are inherent parts of the classi�cation scheme. Both tell us the story of the formation of pegmatites (Table 1). It may be subjected to a tripartite subdivision being focused on the geodynamic evolution of the host setting and by analogy to tripartite subdivision considering the mineral deposition in relation to the kinematic processes in the crust where the pegmatites eventually were emplaced. The entire process of pegmatization is connected with mobilization and emplacement of feldspar-, quartz- and mica-enriched in bodies within an ensialic orogen characterized by an abnormally thick crust (Variscan-type orogen). There are two environments of formation with a rather thick crust where pegmatites are either reactivated (Alpine-type) or “refueled” from the mantle (Rifttype); the more ensimatic these neighboring geodynamic settings are, the less likely the occurrence of � nding pegmatites in these environments (Fig. 6a).The three geodynamic environments arerepresentative of the three principal processes responsible of forming a pegmatitic ore body and controlling its ore composition: (1) intracrustal mobilization, (2) subcrustal mobilization, and (3) physico-chemical reactivation (Table 2). Pegmatitic ore may have originated by one of these processes or owing its structure and composition to all three processes. The complexity of a pegmatite is the mirror image of the involvement of these three processes by quantity and quality. The spectrum covers a wide range from simple unzoned feldspar –quartz pegmatoids in metamorphic rocks (migmatites) to dismembered zoned multi-element/multi-mineral pseudopegmatites along shear zones. A similar tripartite subdivision as performed for the geodynamic position of the host environment can also be done for the pegmatites themselves. They are part of the thrustbound and fold-related metamorphogenic deposits (type II), collision and intrusive-related deposits (type III) and deep-seated lineamentary remobilization (type V) see for types Section 6. The 1st order term or type of pegmatitic/aplitic rocks controls the temporal relationship between the pegmatitic rocks and the country rocks. The term “granitic pegmatites ” is downgraded to a type of pegmatite and no longer plays the key role as the father of all things. It has to share its compartment in the classi�cation scheme with “syenitic pegmatites ” and is hierarchically placed at the same level as metapegmatites or pegmatoids. Pegmatites and granites are two sides of the same coin, being related to a heat event in a crustal section, triggered either by crustal or subcrustal processes. It has to be noted that the role of the subcrustal sources in terms of heat and element input has been underrated for too long a time whereas the role of so-called parental granites for the generation of pegmatites has been overestimated during the past. The mantle may either by tapped by (sub)vertical deep-seated lineamentary fault zones or by (sub)horizontal thrust planes which along with a steepening of their planar element lead to a mantle detachment at depth. Such mantle slaps may be exposed as it is the case with the Lizard Complex juxtaposed to the Cornubian Sn –W Ore�eld or they may left concealed as shown for the NE Bavarian Basement in the cross section of Fig. 9f. The role of parental granites has been taken rather dogmatic but left untested in the � eld and other processes of mobilization have been denied. Pegmatites and granites may resemble each other, like two brothers, yet neither of them will become the other's father. Why is one of them successful and the other is not good at handling things?. Pegmatites, the successful off-springs, are (1) focused and guided by structures, (2) open to crustal and subcrustal sources, (3) smaller in size with their elements concentrated more intensively, and (4) open for interaction with their environment around (skarn, episyenites, albitites). The latter set of processes may be

539

present near granites too butis only restrictedto the contact of granites. The paramount factors making pegmatites so successful in concentrating rare elements are the geodynamic setting and the structural geology. The approach taken in this study to explain how the pegmatitesevolved through time closely resembles the approach taken by petroleum geologists who have been dealing with petroleum systems since decades. It involves a source rock which may gas prone or oil prone, it needs a migration pathway described at its best by structural geologists, and last but not least a trap and a seal (Magoon and Dow, 1990). Delineating a petroleum play/pegmatite � eld starts up with a “ basin analysis ” encompassing all kinds of applied geosciences from geology to geophysics conducted at the surface and in the underground. There are �ve “basins” or geodynamic settings, out of which only three are pegmatite-prone (Fig. 6a). The Variscan-, Alpine- and Rift types are the only geodynamic settings held to be pegmatite-prone, because they have “ source rocks” for elements which are going to be concentrated in pegmatites, they provide physical regimes to allow for an ascent and pathways such as deep-seated lineamentary rifts or shallow thrust and shear planes for felsic melts to migrate into the traps. Both planar architectural elements are used by A- and S-type granites, respectively, and by pegmatites as well. Pegmatites are concentrated as being trapped in a structure sealed off by metamorphic or magmatic roof rocks (Figs. 1, 4, 7, 8, 9, 23, 24, 46, and 47 ). It is the pegmatites s.str., plutonic pegmatites and pseudopegmatites that are found mobilized, and immigrating into an environment different from their birthplace. There are also “oil shows ” close the source rock, which � nd an analogue in the in-situ anatectic pegmatoids where the felsic mobilizates did not travel far off the place of mobilization (Figs. 21, 35, Table 1). And what about “oil and gas seeps”, where hydrocarbons enter the near-ambient environments? It is the various types of hydrothermal alteration whose textures and minerals can be found in some pegmatite systems. The deposit-conservative to enhancing types are described in Table 12, some destructive types, such as episyenites are depicted in Fig. 41. The change from the hypogene to the supergene stages can be gradational (Table 12) or can be marked by a hiatus. Granites and pegmatites are only two sides of the same coin; the granite is often a mirror image of diffusion and dissemination, the pegmatite of trapping and concentration. Dissemination of elements does not exclude the formation of an economic target, as exempli�ed by intragranitic low-grade-large-tonnage deposits of U (e.g. Rössing, Namibia), Ta –Nb – Li –W (e.g. Yichun, China), and REE –U –Nb (e.g. Aktiuz, Kyrgyzstan) which can, in places, be transitional into pegmatites or limited to the granite, proper, as it is the case with some intragranitic greisen deposits of Sn and W where the adjacent pegmatites are barren. To keep on emphasizing the similarities between rare-metal pegmatites and the petroleum system, the intragranitic rare-metal concentration with no seal can be compared with the so-called “ unconventional hydrocarbon” deposits, representatives of which are found in the Athabascan Basin, where oil sands are exploited in open pit mining operations. Sparking a discussion of pegmatites and granites in connection with a petroleum system may be held to be a bit provocative but it is intended to leave the beaten tracks of conventional �xed thinking which is too strongly entrenched in mineralogy. Opposed to the study by Dill (2015), in which mineralogy has an equal share besides geology and geophysics when it come s to account for the evolution of a pegmatite system, in the current study emphasis is placed upon the genetic and applied parts of ore geology. It is necessary, to look occasionally over the edge of a test tube or PC and leave the of �ce and take a look at the target area where pegmatites and granites developed embedded into the country of a particular geodynamic setting. Even if the P –T regime of the current object of study is different from that of a petroleum system a

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change from a �xed towards a more �exible mindset is necessary in the study of pegmatites and most adequately approximated through these natural processes well studied by petroleum geologists. The 2nd order term shape and structure enable us to � ne-tune the positioning of the pegmatitic rock. Its morphology, size and siting within the country rocks is of assistance for theattribution of the pegmatites to one of the aforementioned types II, III and V that were mentioned as reference deposits. A more detailed attribution and interpretation of the pegmatite can be achieved by disentangling the element association (3rd order term= chemical quali�er of rare metal pegmatitessensulato) andmineral assemblage (4th order term = mineralogical quali �er of industrial mineral pegmatites) (Fig. 6b, c, Table 2). For example, lithium pegmatites are characteristic of intracrustal processes as shown in Fig. 6b and Table 2. The presence of columbite-(Fe) in the pegmatite is indicative of a deep-seated structure which tapped a subcrustal source. Stable cratonic conditions with a persistent refueling from the mantle may pave the way from a pegmatitic rare element deposit eventually into a carbonatitic deposit (see Brazil, and Subsaharan Africa). The often quoted zonation of elements and minerals in pegmatites around a hypothetical parental granite is a remake of “Breithaupt's succession of element associations” claimed to be representative of a decrease in temperature (katathermal to telethermal) and the depth of formation: Au–Ag Cu sul �de Pb–Zn–Ag Ag–Bi –Co–Ni–U Sn–Ag–Bi–W Sb–Hg– As–Se oxidic Fe –Mn –Mg minerals non –metallic stage with B and F. Nobody will apply today such a rigid scheme of classi �cation anymore. The practical work in the � eld with pegmatites does not allow us pigeonholing these felsic rocks into a rigid scheme of classi�cation using marker minerals or typomorphic element associations pointing to a certain depth or physical–chemical regimearound a hypothetical granite. Thelarger thesize andthe more variegated the element spectrum of the pegmatites become the lesser the applicability of in �exible classi�cation schemes devoid of any outlet into the genetic and applied economic geology. ⇒

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9.2. Economic outlook

Pegmatites andtheirclastic aprons will be left unchallengedas far as the exploitation of colored gemstones is concerned (Fig. 49). The hardrock deposits will still have a say when the requirements for the raw material are very strict (ultra-high-purity quartz) and a shortage of electronic and strategic elements or nuclear energy is looming (Fig. 49). Exploitation of industrial minerals from hardrocks is competitive if no easy-to access deposits of similar quality are close-by and the labor costs are moderate. Low-grade large tonnage deposits are a challenge particularly for lithium. The pegmatites will maintain their position as a source for those elements which make up the lion share in the mineral association quartz and feldspar. Acknowledgments

I acknowledge with thanks the support of the following institutions and companies: Wasserwirtschaftsamt Weiden [Water authority] Weiden, Fa. Eder Brunnenbau Deutschland GmbH, Ingenieurbüro GolHo, Gottfried Feldspat GmbH, and Amberger Kaolinwerke AKW. I would like to extend my gratitude also to, R. Göd, S. Lahti for their hints to literature and photographs. A. Müller (Geological Survey of Norway) provided some photographs. H. Wotruba (RWTH Aachen — Department of Mineral Processing) provided some helpful information as to the processing of some rare metals in pegmatites. I extend my gratitude also to Rio Tinto

Rössing UraniumLimited (Swakopmund, Namibia)for kindly providing photographs of its mining operation. I would like to express my thanks to R. Thomas and an anonymous reviewer for their comments made to this paper. I would like extendmy gratitude also to theeditor-in-chief F. Pirajno for his editorial handling of this paper for ORE GEOLOGY REVIEWS and to T.J. Horscroft for initiating this invited review. I would like to thank also H. Moorthy and her team for their technical support. S. Glück.and C. Vinnemann redraftedthe digital maps on gemstones in pegmatites. H.J. Sturm made some colored drawings. References Achstetter, M., 2007. Aus Hornberg im Schwarzwald:Aquamarin in Edelsteinqualität und weitere Neufunde. Lapis 32, 13–21. Ackerman, L., Zachariáš, J., Pudilová, M., 2007. P–T and �uid evolution of barren and lithium pegmatites from Vlastě jovice, Bohemian Massif, Czech Republic. Int. J. Earth Sci. 96, 623–638. Ackermand, D., Windley, B.F., Raza�niparany, A., 1989. 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geography at Würzburg, Erlangen and Aachen universities. He was awarded a Diploma/M.Sc (geology), Dr. (mineralogy), Dr. habil. (applied geology/economic geology) and a Dr. honoris causa while he was appointed Assoc. Prof. and awarded honorary professor and professor invitado. During more than 35 years, working as junior researcher in soil sciences (Bayreuth University), senior researcher (economic geology, applied sedimentology, technical mineralogy) at the Federal Institute of Geosciences and Natural Resources (Hannover) and in a management position with the German Continental Deep Drilling Program he gathered practical experience in about 87 regions/countries on 6 continents. In addition, he teaches/taught at 4 German universities and 20 abroad. His "paperwork" consists of 326 publications (219 reviewed, 289 senior-authored), 101 abstracts and 1 patent and led to 5 discoveries of mineral occurences and 1 oil show. He is an Assoc. Editor of OGR. He was awarded the Quintino-Sella Prize at the 32nd Geological Congress, Florence and a scholar of the German National Merit Foundation. From 1969 to 2006 he was as volunteer and part-time soldier with the artillery and MilGeoService holding a � nal rank of a colonel of the German Army Reserve. Riding the hobbyhorse means for him archeometallury, history, aerial warfare/aviation and collecting postal letters. In 2014 he retired from of �ce.

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H.G. Dill / Ore Geology Reviews 69 (2015) 417 –561 Table x

index of sites. Site

Country

CMS classi�cation (Short version)

Status

Page

Adun-Tschilon Mountain Aksoran Alba Albera Region Almendra Altai Altenberg Alto Ligonha Alvarrões Pegmatite Amarante Ambatoabo Ambatofotsikely Ambatohasana Ambatondrazaka Ambatovita Amorican Massif Ampangabe An Phu Analalava District Andapa District Andilamena Andranondambo Andravory District Angerkristallin Anjahamiary Anjanabonoina Ankazobe-Vohambohitra Antananarivo Antandrokomby Antsirabe Antsongombato Apaligun Aquarius Range Aracuai Arga Aries Assunção Mine Aukas Azad Baja California Bakamuna Bancroft Baragoi District Barauta Barra De Salinas Rubelita Barroso-Alvão pegmatite � eld Barruecopardo Bayan nuur Bayerischer Wald Beauvoir Bendada Benson No. 3 Bernic Lake (Lac-du-Bonnet) Tanco Betafo-Antisabe Bikita Birkhöhe Black Hills Black Mountain Dunton Mine Black Range/New Mexikco Bližná I Blötz

Russia Kazakhstan Spain France Portugal Russia Germany Mozambique Portugal Portugal Madagascar Madagascar Madagascar Madagascar Madagascar France Madagascar Vietnam Madagascar Madagascar Madagascar Madagascar Madagascar Austria Madagascar Madagascar Madagascar Madagascar Madagascar Madagascar Madagascar Pakistan USA Brazil Portugal Zambia Portugal Namibia Kashmir (India–Pakistan) Mexico Sri Lanka Canada Kenya Zimbabwe Brazil Portugal Spain Mongolia Germany France Portugal Zimbabwe Canada Madagascar Zimbabwe Germany USA USA USA Czech Republic Germany

Gem site Deposit Gem site Deposit

448 514 469 469 484 463 435,445,447,448,480,514 448,463,470,473,506 477,484 450,545 523 475 475 470 519 463 475 516 439 448 448,535 521 448 520 516 463 448 479,547 448 541 448 448 471,548 429,463 513 469 484 463 521 463 521 476,500,518 448 522 448 484 450 515 522 477 485,512 508 485 448 448,470,481,484,495,496 487,502 451 463 517 472,490,525 487,502,521

Bodmin (Cornwall) Bogala Bogd uul Böhmer Wald Boise Bokan Mountain Bom Futuro Boqueirão Boroborema Province Borborema Bortschowotschnom Botogol

Great Britain Sri Lanka Mongolia Germany USA USA Brazil Brazil Brazil Russia Russia

Be-aquamarine Feldspar Si-quartz (Nb/Ta–U)–Be–Li–P Li–F–P F–B–Si–tourmaline–amethyst–topaz Mo–W–Sn Li–Nb/Ta–Be–B–beryl–tourmaline Li–F–P Sn–W feldspar–mica (Be)–Nb/Ta–U–Th (Be)–Nb/Ta–U–Th B–Be Cs–Li–zeolite Be (Be)–Nb/Ta–U–Th feldspar (amazonite) Be–beryl Be–beryl Be–beryl Al–sapphire Be–beryl kyanite–staurolite Li–B–feldspar (amazonite) B–tourmaline Be-beryl (F–REE–Bi–Li)–Nb/Ta–Be–B Be–rhodizite Si–quartz Be–rhodizite Be–aquamarine REE F–Be–B–aquamarine –topaz Zn–Be Si–amethyst (F–Mo–Bi–Cu–W–Sn–B)–Li–U–Nb/Ta–Be–P B–tourmaline Al–ruby–sapphire–spinel F–B–Si–tourmaline–quartz–topaz Be–W–Al–ruby–spinel Th–U–nepheline Be–aquamarine Al–sapphire Be–aquamarine (U–Zn–Be–REE)–Sn–Nb/Ta–Li–P Sn–W feldspar B–P F (Sn–Nb/Ta–Be–As–Li)–U–P (Be–F–REE–Sn–P)–Li–Nb/Ta–beryl Be–B–P–Sn–Li–Ta Be-beryl Cs–(Rb)–Be–Li–Nb/Ta B–Nb/Ta–P Nb/Ta–Be–Li–Sn–Si–quartz B-tourmaline feldspar (moonstone) (Li–P–W–Nb/Ta)–B–REE REE–Nb–P–B corundum– garnet–andalusite–cordierite Si–smoky quartz graphite Sn–W–As–Pb–Zn–Cu As–Sc–U–Li–Be–B–F–REE–Nb–P Be–aquamarine U–REE–Nb–Zr Li–F–W–Sn (Be–F–U–Bi–Pb–Zn–Cu–B–Sn)–Li–Nb/Ta–P Be–B–kaolin B –tourmaline graphite

Gem site Deposit Deposit Deposit Deposit Deposit Deposit Deposit Deposit Deposit Gem site Gem site Gem site Deposit Gem site Deposit Gem site Gem site Deposit Gem site Gem site Gem site Gem site Deposit Gem site Gem site Deposit Gem site Gem site Deposit Deposit Gem site Deposit Gem site Deposit Deposit Deposit Deposit Deposit Gem site Deposit Deposit Gem site

Gem site Deposit Deposits Gem site Deposit Deposit Deposit Gem site Gem site Deposit

469 506,523 471 481,487,502,506,520,521 448 462,476,532 452,478 487 448,478,487,507,534,533,536 463 523 on next next page) page ) (continued on (continued

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Country


Branchville Brandberg Broken Hill Bulache (Gilgit) Bupo Burmado Cachoeira Cairngorm Campbell Island Cañada Cannington Cap de Creus Carnaiba Region Carrara Near Harar Casa Ventura Castelinho Caxias Chamachhu Chibina Tundra (Khibiny) Chipata Chitral Cínovec Coimbatore Comechingones Connecticut Conselheiro Pena Cooma Cornubian Coronel Murta Corrego Frio Criollo Crystal Mountain Dac Lac Danba Danie Darra-I-Pech Dartmoor Dillenberg (Tillenberg)/Waldsassen Ditró (Ditrău) Doce Doko-Balistan-Gilgt Dolní Bory Don Duong Drachselrieth Dunton pegmatite Dusi (Garba Tula) Dusserud Dusso (Balistan-Gilgit) Dusso Nyit Bruk Egbe area Ehrenfriedersdorf Embu-Meru Erling near Spittal Erongo Mountain Espirito Santo Etiro Eurajoki Evje-Iveland Fianarantsoa Fichtelgebirge Flint Ridge Foote Lithium Kings Mts. Forrestania Franciscopolis North Froland Fugong Fuji-San Gascoyne Glen Buchat Godarpur Golpejas Gonçalo Gone — Shirgar Valley Gongshan Goriko Zuun Bayan

USA Namibia Australia Pakistan Ethiopia Brazil, Bahia Brazil Great Britain Canada Spain Australia Spain Brazil Ethiopia Zimbabwe Brazil Brazil Pakistan Russia Zambia Afghanistan Czech Republic India Argentina USA Brazil Australia Great Britain Brazil Brazil Argentina USA Vietnam China South Africa Afghanistan Great Britain Germany Romania Brazil Pakistan Czech Republic Vietnam Germany USA Kenya Sweden Pakistan Pakistan Nigeria Germany Kenya Austria Namibia Brazil Namibia Finland Norway Madagascar Germany USA USA Australia–Western Australia Brazil Norway China Japan Australia–Western Australia Great Britain Pakistan Spain Portugal Pakistan China Mongolia

(F–REE–Zn–Bi–Nb/Ta)–Li–U–P B–tourmaline feldspar (amazonite) Be–beryl Be–Nb/Ta–Li–P Be–B–beryl (Sn–Be–P–Nb/Ta)–Li Si–smoky quartz Th–U (U–REE–Sn)–Nb/Ta–B–Li–P garnet (U–Sn–F–Nb/Ta–Li–Zn)–Be–B–P Be–chrysoberyl Be–beryl Be–P–Li–Nb/Ta Be–chrysoberyl F–topaz Be–aquamarine Zr–REE–nepheline B–F–tourmaline–topaz Be–beryl Rb–Cs–Li–Sn Be–beryl Be–Nb–Ta–P–U Be–P–feldspar–mica (Be–P–Sn–REE) –Nb/Ta–Li–B cordierite B–Sn–W B (Be–B)–U–P (Zn–Bi–Mo–Cu–F)–Be–Nb/Ta–U–P Sc–Be–F Al–corundum Be–beryl Be–beryl Be–aquamarine Si–amethyst andalusite Ti–Zr–REE–sodalite Be–aquamarine Be–aquamarine sekaninaite–feldspar Si–amethyst Nb–P garnet–andalusite (Sn–As–Nb–Ta–Li)–B–Be–U–P Al–sapphire REE–Nb/Ta Be–beryl F–topaz Sn–Nb–Ta (Mo–Zn–Bi–U–F–As)–B–Be–Li–P–Sn–W Be–beryl P–Be–Be Be –aquamarine Be–aquamarine (Cs–REE–Bi–B–Li–Nb/Ta) –P Sn–Be–W–Zn Sc–quartz B–tourmaline Sn Si–quartz U–Nb/Ta–Sn–Be–Li–P B–tourmaline B–tourmaline Si–quartz B–tourmaline Si–quartz Be–beryl Si–smoky quartz Be–beryl As–Sn–W F F–topaz B–tourmaline F–topaz

Status

Gem site Gem site Deposit Gem site Deposit Gem site Deposit Gem site Gem site Deposit Gem site Gem site Gem site Deposit Gem site Gem site Large deposit Gem site Deposit Deposit

Deposit Gem site Gem site Gem site Gem site Deposit Gem site Gem site Deposit Gem site Deposit Gem site Gem site Deposit Deposit Gem site Deposit Gem site Gem site Deposit Deposit Deposit Gem site Gem site Deposit Gem site Gem site Deposit Gem site Gem site Gem site Gem site Gem site Deposit Gem site Gem site Gem site

Page 512 463 516 448 470 448,463 484,496 469 476 450,484 522 477 448 448 508 448 463 448 518 463,479 448 440,447,461 32 476 485,512 473 520 445,449,460,461,477,480,537,539 459,478 487 513 509,513,537 501,521 448 448 448 469 519 500,518 448 448 501,520 469 521 512 521 426,472 448 478 454 435,445,449 448 441 448 448 473 459 86,500,517 463 447,449,461,477,480,481,519,520 469 498 463 463 517 463 469 448 469 448 435,450 477 463 463 463

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H.G. Dill / Ore Geology Reviews 69 (2015) 417 –561 Table x (continued)

Site

Country


Gouesnach Governador Valadares Greenbushes

France Brazil Australia

Be–B Be–B–aquamarine–tourmaline (U–REE)–Sn–Be–P–B–Cs–Li–Nb–Ta

Groote Spitzkopje Guangdong Guangxi Guarda-Belmonte area Gur-Salak Konar Province Gwantu Hackman Valley, Mt. Yukspor Haddam Hagendorf

Namibia China China Portugal Afghanistan Nigeria Russia USA Germany

F F–topaz F–topaz F Be–aquamarine Be–emerald graphite Be–beryl Be–Nb–Li–P

Hagendorf –Pleystein Province Haliburton-Bancroft Haramosh Harris Helikon Hematita Hitterö Hoh, Braldu Valley Holene Homestead Hornachuelos, Córdoba Hühnerkobel Hunt Hunza Hunza Valley Nagar Hushe Hyakule Ijero area Ikalamavony Ilimaussaq Ilmeny Gory Imbert pegmatite at Montbrison Irondro Isahara Itabira Itaguau Itrongay Iveland Ivigtut Izumrudnye Kopi area, Ekaterinburg Jaguaribe Area Jegdalek Jequitinhonha Province Johan Beetz John Saul ruby mine Jonas Mine (João Pinto mine) Jos Plateau Kafubu Area Kamativi Kantiwa-Ye·lya Kapiri Mposhi Kapirikamodzi Hill Karibib District Karlowa Karoi-Miami Kashmir Katlang Ghundao Hill Kef � Kekertausak, Narsarsuk Kenticha Kerala Khaltaro-Gilgit Khumbu Kigesi Kings Mountains Kishangarh Klein–Spitzkopje Knoydar Kobokobo Koktokay

Germany Canada Pakistan Great Britain Namibia Brazil Norway Pakistan Norway Namibia Spain Germany Canada Pakistan Pakistan Pakistan Nepal Nigeria Madagascar Greenland Russia France Madagascar Madagascar Brazil Brazil Madagascar Norway Greenland Russia Brazil Afghanistan Brazil Canada Kenya Brazil Nigeria Zambia Zimbabwe Pakistan Zambia Malawi Namibia Namibia Zimbabwe India Pakistan Nigeria Greenland Ethiopia India Pakistan Nepal Uganda USA India Namibia Great Britain DR Congo China

(Sc–As–Be–Zn)–Li–Nb–P Al –sapphire F Be–beryl (Cs–P–B)–Nb/Ta–Be–Li Be–chrysoberyl quartz–feldspar–mica B–tourmaline quartz–feldspar–mica (Bi)–Be–Nb–Ta–Li–P (B–F)–Be–Nb/Ta–REE–U–P (Sn–As–F–U)–Be–Nb–P (Re)–Mo Al–ruby–spinel Be–aquamarine F–topaz B–F–tourmaline Sn–Nb–Ta (W–REE–Bi)–Be–P–Li–Nb/Ta Ti–U–Y –REE–Zr–Nb Al–sapphire P–B Be–emerald B–F–Be Be–chrysoberyl Be–chrysoberyl feldspar (orthoclase) Be–aquamarine Al–cryolite (P–Li–B–Bi–Mo–Nb–Ta–F)–Be Be–aquamarine Al–ruby–spinel B–tourmaline– U–Th Al–ruby/sapphire (Be–P–Sn–REE)–Nb/Ta–Li–B F–Nb/Ta–W–Sn–topaz (F–Zn–P)–REE–B–Nb–Ta–Be (B–REE–W–P)–Nb/Ta–Sn–Li B–tourmaline Be–beryl Quartz–feldspar–mica (Bi)–B–Nb–Ta–Sn–Be–Li–P–tourmaline Nb/Ta–Sn–Li Be–beryl B–tourmaline F–topaz B–tourmaline Nepheline–zeolite–sodalite (Sn)–Be–Li–Ta graphite Be–emerald B–tourmaline Au–Bi–Sn–W Sn–Li Al–corundum–nepheline B–tourmaline Be–beryl (B –Sn–REE–Li–As–Th)–P–U–Be–Nb B–tourmaline

Status

Gem site Deposit Gem site Gem site Gem site Gem site Deposit Gem site Deposit Deposit Gem site Deposit Gem site Deposit Gem site Deposit Deposit Deposit Deposit Deposit Gem site Gem site Gem site Deposit Deposit Giant deposit Deposit Gem site Deposit Gem site Gem site Deposit Gem site Deposit Deposit Gem site Deposit Gem site Prospect Deposit Deposit Deposit Deposit Deposit Gem site Gem site Deposit Deposit Deposit Gem site Gem site Gem site Gem site Deposit Deposit Gem site Gem site Deposit Deposit Gem site Gem site Gem site DepositGem site

Page 463 448,463 435,470,476,484,494,510,526,531, 534,537 478 463 463 477 448 448 523 448 431,487,502,506,511,512,521,522, 524,525,535 485,498,525 521 478 448 506 448 504,522 463 504,522 508 485 487,502,521 514 448,521 448 463 463,479 454 473 473,474,476,531,532 521 463 448 470 448 448 517,523 448,461,485 477,533 471 448 521 463 476 121 479 488,506,507 470 428,439,451,488,499,507,508 463 448 523 473 452 448 463,521,522 463 463 518 470 523 448 463 513 498,513,537 518 463 448 448,473,486 463 (continued on next next page) page ) (continued on

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Status

Koktokay No. 3 (Altay No. 3) Kol'Skiy Poluostrov Königshain Koralpe Korgal Kotokay Kožichovice II Kragerö Kuangding Kukurt Kumkol Kunar Kunar Province Kuortane Kuru Úrte Ky Son La Canalita La Madera Lac Alaotra Lagham Province Laghman Lake Alaotra District Lalín Lana Mine, Ouro Preto, Minas Gerais Lands End Las Palomas–San Luis Leeuw Kop Leeuwspruit Letitia Lake–Two Tom Limoeiro Little Three Mine, Ramona Ljosland Loc Tan Los Andes Lovozero

China Russia Germany Austria Afghanistan China Czech Republic Norway China Tajikistan Kazakhstan Afghanistan Afghanistan Finland China Vietnam Spain Argentina Madagascar Afghanistan Afghanistan Madagascar Spain Brazil Great Britain Argentina South Africa South Africa Canada Brazil USA Norway Vietnam Chile Russia

(REE) –Be–B–Cs–Nb/Ta Li–mica Si–quartz P–U–F–Ag–Li–Sn–W–Pb)–Bi–Nb/Ta–Be–REE B–Nb/Ta–Be–Li–P–tourmaline Cs–Sn–B–Nb/Ta–Li–Be–tourmaline Be–aquamarine Be quartz–feldspar–mica Be–aquamarine Be–aquamarine Si–amethyst Be–aquamarine B –tourmaline B–tourmaline B–tourmaline Si–smoky quartz Sn–W zeolite Si–amethyst B–tourmaline Be–Li–garnet (kunzite) Be–chrysoberyl Sn–Li–Be–P F–topaz Si–amethyst Be–aquamarine Be–chrysoberyl Be–beryl Y–Th –REE–Nb–Zr–Be F–topaz Be–beryl garnet F–topaz Si–quartz Ti–Zr–REE–Ta–Nb

Deposit Gem site

Luc Yen Lukusuzi Lun Lundazi Area Luumõki Lyangar Madeira Mahajamba Mahenge Maine Province Majayahan Makanjior Malakialina Malkhan Man Shield Mananjary Mangare area Mangualde Manjaka Manono-Kitolo Marambaia Marchaney Mariupol Markocice Marropino Maršíkov I–III Masino-Bregaglia Mavusi Mawi Mazán Mboro McKay Head Menez–Goaillou–en–Coray Menzelhof Miass Middletown Mid-German Crystalline Rise Miesbrunn Modot

Vietnam Zambia Mongolia Zambia Finland Uzbekistan Brazil Madagascar Tanzania USA Somalia Tanzania Madagascar Russia Sierra Leone Madagascar Kenya Portugal Madagascar DR Congo Brazil Germany Ukraine Poland Mozambique Czech Republic Italy Mozambique Afghanistan Argentina Madagascar Canada France Germany Russia USA Germany Germany Mongolia

Page

496 469 468,472,508 Deposit 426,435,440,469,481,483,492,494,510 Deposit 463,479 Gem site 448,518 470 Deposit 504,522 Gem site 448 Gem site 448,518 Gem site 469 Gem site 448 Gem site 463 Gem site 463 Gem site 463 Gem site 469 Deposit 450 519 Gem site 469 Gem site 463 463,522 Gem site 448 Deposit 450 Gem site 463 Gem site 469 Gem site 448 Gem site 448 Gem site 448 Medium deposit 531 Gem site 463 Gem site 448 522 Gem site 463 Gem site 469 Super giant 473,531 deposit B–tourmaline Gem site 454,463,516 B–tourmaline Gem site 47 feldspar Deposit 515 Be–B–beryl Gem site 448 Be–beryl Gem site 448 feldspar Deposit 514 Nb/Ta–Y –REE–Li–Zr–U–Th–Sn Deposit 473 Si–quartz Gem site 469 Al–ruby Deposit 522 Be–P–feldspar–mica Deposit 513 Sn–Li–Ta Deposit 508 Be–beryl Gem site 448 Be–beryl Gem site 448 B 479 Sn–Nb/Ta Deposit 508 (F–B–P–Mo)–Be Deposit 470 B–kyanite–ruby Deposit 479,521 (F–B–Zn–Pb–Mo–As–Cu)–Be–Li–U–P 484 Li Deposit 495 (Cs –Pb)–Nb/Ta–Li–Sn Deposit 23,35,83,115 F–topaz Gem site 463 B–dumortierite 520 Zr–nepheline–sodalite 518 REE–U–Th 475 Deposit (REE –Bi)–Li–F–Be–Nb/Ta 473 (Zn)–REE–Nb/Ta–Be 472 Nb/Ta–Y –U–REE 472 REE–U Deposit 473 Cs–Sn–Nb/Ta–Li–Be–B–aquamarine–tourmaline Deposit 448,463,479 Al–corundum –andalusite 521 (B)–Bi–REE–Nb/Ta Deposit 473 scapolite 518 (P–As–Cu)–Sn–Be 463 feldspar Deposit 516 Be–F–Si–beryl–quartz–topaz Gem site 448,463 512 (W–As–Bi–Cu–Mo–F–REE) –B–Nb/Ta–Li–Be–P (B–Li–Be–P)–REE–U 483 Zr–Nb–B–P 511,522 Sn–W–As–Pb–Zn–Cu 435,471

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Moldanubian Zone

Germany

B–Be–As–B–Zr–Nb–F–P

Deposits

Moneragala Mont Saint-Hilaire Montebras Monts d'Ambazac Morondava Moss Motzfeldt Sø Mount Auburn Mount Cattlin Lithium Mine, Ravensthorpe Mount Mica Mount Mica Mphungu Muiane Münchberg Gneiss Complex Mursinska District Mursinska Mts Murupane Murrua Mwani Baboon Hill Mwanza Nacala Naegi Namecuna Nassarawa Näverån Nilaw Nilaw Niyit-Bruk Ntebeni Nui Phao–Tam Dao District Nuristan Nyet Odegi Oedental Okkampiitya Olary Province Older Granite Suite Orissa Orivesi Orlovka Oslavice Otov Ouro Preto Pabrok Pala Palermo

Sri Lanka Canada France France Madagascar Canada Greenland USA Australia

Al–sapphire Zr Li–P–F–Sn–Nb/Ta–mica–kaolin Be Si–amethyst Mo Zr–Be–REE–Nb–Ta B–tourmaline (F–Be–Sn)–Nb/Ta–Li

Deposit

425,447,454,462,468,470,477,480, 481,482,483,484,485,489,490,494, 496,499,502,506,513,515,518,519, 520,521,531 522 473 108 463 469 514 56 463 494

USA USA Malawi Mozambique Germany Russia Russia Mozambique Zimbabwe Malawi Mozambique Japan Mozambique Nigeria Sweden Pakistan Afghanistan Pakistan Zimbabwe Vietnam Afghanistan Pakistan Nigeria Germany Sri Lanka Australia Nigeria India India Russia Czech Republic Czech Republic Brazil Afghanistan USA (California) USA

Pampean Pegmatitic Province Panasqueira Paprok Paraiba Paredes da Beira Pattalai Pechtelsgrün Phakuwa Pikes Peak Pingwu Pleystein

Argentina Portugal Pakistan Brazil Portugal India Germany Nepal USA China Germany

B–tourmaline (Sn–As–Zn–Zr)–Tb/Nb–U–B–Be–P Mica–quartz –feldspar B–tourmaline (kyanite)–feldspar sodium Be–beryl–aquamarine B B–tourmaline Be–aquamarine Zr B–tourmaline F–�uorite B–tourmaline Be–emerald Th–(U)–REE B–Be–beryl Cs–Sn–Nb/Ta–Li–Be–B–tourmaline–beryl F–topaz (Zr)–U–Th Sn–Mo–Bi–Be–F–W B–tourmaline F–topaz (Th–Sn–Nb/Ta)–REE feldspar Al–sapphire Be–REE–Li–P–Nb/Ta Nb/Ta–Sn Be–aquamarine F–topaz Nb/Ta–amazonite Nb/Ta–Be–REE Nb/Ta–feldspar F B–tourmaline B–tourmaline (REE–B–Bi–As–Nb/Ta–Cu–Zn–Li–U)– P–feldspar–mica Bi–Nb/Ta–Li–Be Sn–W B–tourmaline B–tourmaline F Be–aquamarine W–Sn B–F–tourmaline–topaz Be–aquamarine Be–beryl Be–Li–Nb–P

Plössberg Ponte Segade Prašivá Püllersreuth Quebec Ramona Rangkul (Kukurtskoe) Reinhardsrieth Reitenberg–Kaitersberg Ribaue Rinchnach

Germany Spain Slovakia Germany Canada USA Tajikistan Germany Germany Mozambique Germany

Zr–As–Nb–Be–P–B Sn–W Be Be–Nb graphite B–tourmaline Li–B–F–Be–scapolite Nb/Ta–P U–B B–tourmaline zeolite

Deposit Gem site Deposit Giant deposit Gem site Deposit Gem site Deposit Gem site Deposit Gem site Gem site Gem site Gem site Gem site Gem site Gem site Prospect Gem site Deposit Gem site Deposit Large deposit Gem site Gem site Deposit Deposit Deposits Gem site Gem site Deposit

Gem site Gem site Deposit Deposit Deposit Gem site Gem site Gem site Deposit Gem site Gem site Gem site

Deposit Deposit Gem site Deposit Deposit Gem site

463,474,512 463,474,512 491,515 463 426,481,482,483,515,519,520 448 479 463 448 473 463 463 463 448 472 448,463,479 448,463,479 463 475 431 463,479,522 463 473 516 522 494 443 448 463 516 472 487,494,502,516 463,478 463 463 485,512,513 476 440,450,460,461 463 426,454,459,463,477,479,524,518,533 477 448 435,447 463,479 448 448 431,453,475,477,480,487,489,495,502, 503,506,507,517,518,522,523,524,525 469 450 470 426,487,502 476,517,532,537 463 518 487,502 521 463 519 (continued on next next page) page ) (continued on

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Status

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Rio Doce Province Rio Grande Do Norte Rocky Mountains Roncadeira Borborema province Rondônia Province Rössing Rothau Rožná Rubikon Ruda nad Moravou Ruggles Mine, Grafton Sadisdorf Sahatany District Salgadinho Salpond Sambesi Graben San Diego County San Luis Sandamap Santa Leopoldina Santa Tereza Satzung–Erzgebirge Saxo–Thuringian Scaër–Langonnet Scheibengraben Schneckenstein Schöllnach–Tittling Schoonmaker Mine Strickland pegmatite Schwarzeck Segura Seiland Island Separation Lake Serra Da Mesa Serro Shagait-uul Shengus Sherlovaya Gora Shigar Valley Shingus Shingus–Dusso Shizhouyuan Sibweza Sichuan Sierra De Ancasti Sierra De Cordoba Sierra De San Luis Sierra Morena Sierra Velazco Silbergrube Sinceni Skalna Brama Socoto South Platte Area Spittal a.d. Drau Spitzkopje Spruce Pine Spruce Pine Chalk Ray Mica Mine Spruce Pine McHone Mine St. Ann's Hurungwe District St. Austell Moor St. Radegund Stak–Nala Störnstein Strange Lake Strathmore Suishoyoma Szklarska Poręba Szklary Takob Talate Taquaral Tchenzema–Uluguru Mts. Teo�lo Otoni Terra Branca Minas Gerais

Brazil Brazil Canada Brazil Brazil Namibia France Czech Republic Namibia Czech Republic USA Germany Madagascar Brazil Ghana Zambia USA Argentina Namibia Brazil Brazil Germany Germany France Czech Republic Germany Germany USA

B–tourmaline B–Be–aquamarine–tourmaline Si–quartz (Zn –Be)–Sn–Nb/Ta P –Li–F–Nb/Ta–Sn–W (F–P–As–Mo–W)–Th–REE–U (Sn–P)–B–Be Sn–Be–Nb/Ta–F–B–P–Li Nb/Ta (P–Zr–U–Th)–Nb/Ta–REE (REE–B–Bi–As–Nb/Ta–Cu–Zn–Li–U)–P W–Sn B–tourmaline B kaolin Be–beryl B–tourmaline Si–quartz (B–Nb/Ta) –Sn–Li–P Be–chrysoberyl Be–chrysoberyl sekaninaite B–Be–F–Li–Sn–U–P–As Be–B Be–Nb F–topaz (Sc–Li–Nb–F–B–U)–REE–Be–P–zeolite (Zn–REE–F–U)–Be–P–B–Li

Gem site Gem site Gem site Deposit Deposits Deposit

463 448,463 537 488 452 453,462,475,476,488,528,533,539,540 520 491 488,506 472 512 434,445,31,32,64,510 463 479 507,524 448 463 452 486 448 448 520 445,469,477,480,481 463 504,506,468 489,463 509,519,544 512

Germany Portugal Norway Canada Brazil Brazil Mongolia Pakistan Russia Pakistan Pakistan Kashmir–Pak China Tanzania China Argentina Argentina Argentina Spain Argentina Germany Swaziland Poland Brazil USA Austria Namibia USA USA USA Zimbabwe Great Britain Austria Pakistan Germany Canada Namibia Japan Poland Poland Tajikistan China Brazil Tanzania Brazil Brazil

P–F–B corundum–andalusite–garnet F Zr–sodalite (P–REE–Be)–B–Sn–Nb/Ta–Li Si–quartz F–topaz feldspar F–topaz Be–beryl Be–aquamarine F Be–beryl (Pb–Zn–Ag)–Sn–Mo–Bi–Be–W Be–beryl Be–beryl Be–beryl Be–beryl Be–beryl F Be–beryl Nb–P Be–REE–Th–B–Li–Nb/Ta–Sn As–Nb/Ta–U–REE Be–chrysoberyl REE P–Be–B Be–F–Si–beryl–quartz–topaz feldspar–kaolin (W–Li)–REE–Be–Nb/Ta–mica (B–Be–F–Li) F–topaz Si–amethyst B–Li–Be Be–F–aquamarine feldspar (Li–Zn–Th–F–Nb–Ta)–Be–REE–Zr Nb/Ta–Sn–Li F–�uorite REE–Nb–Ta–Be–B–Sc–F–W P–U–REE–Be–Nb/Ta feldspar B–tourmaline B Si–rock crystal Be–aquamarine–beryl Be–aquamarine

Deposit Deposit Deposit Gem site Deposit Gem site Gem site Gem site Gem site Gem site

Gem site

Deposit Gem site Gem site Deposit Gem site Gem site Gem site Gem site Giant deposit Gem site Gem site Gem site Gem site Gem site Gem site Deposit Deposit Gem site Deposit Deposit Gem site Deposit Deposit Deposit Gem site Gem site Deposit Gem site Deposit Deposit Gem site Deposit Gem site Gem site Gem site Gem site

487,502,521 477 452,473 499 469 463 491,515 463 448 448 478,448 448 545 448 448 448 448 448 478,543 448 535,431 462 472,549 448 472 443 478,448,463 501,498,514,536 498 498 463 469 441,492,520,540 448,47 516 472,473,532 452 47 421 47 514 463,500 459,478 469 448 448

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Thach Khoan Thambani Thomas Range Tisgtung Topsham Třebíč Tres Tetas Triberg Triunfo Trutzhofmühle Tsagaan davaa Tsaratanana 2 Uis Uluguru Mts. Ural Mts. Usakos Valadares Varuträsk V ěžná Vidago Vieux Mayres (Le Château pegmatite) Viitaniemi Virgem Da Lapa Vlastě jovice Vohemar Voi–Taveta Voi–Taveta Volta Grande Vorondolo Wah Wah Wah–Wah Mountains Wäldel–Mähring Waldheim Warriedar Tourmaline Weissenstadt Weissenstein Wendersreuth Whabouchi Wiborg Wildbachgraben Wildenreuth Willie Wimhof –Vilshofen Winnipeng River Wodgina Wolfe/Ontario Wolodarsk Wonder Well–Menzies Xilin Qagan Obo Xuan Le Area Yekaterinburg Yosemite Yuanyang Yunnan Zakhiin–tsohio Zambue Zholtye Vody Zinnwald Zone of Erbendorf Vohenstrauß

Vietnam Malawi USA Pakistan USA Czech Republic Argentina Germany Brazil Germany Mongolia Madagascar Namibia Tanzania Russia Namibia Brazil Sweden Czech Republic Portugal France Finland Brazil Czech Republic Madagascar Kenya Kenya Brazil Madagascar USA USA Germany Germany Australia–Western Australia Germany Germany Germany Canada Finland Austria Germany South Africa Germany Canada Australia Canada Ukraine Australia–Western Australia China Vietnam Russia USA China China Mongolia Mozambique Ukraine Germany Germany

Be –Si–beryl–smoky quartz–amazonite Al–corundum –nepheline Be–beryl Be–aquamarine Be–aquamarine (W–Sn–F–Li)–Be–Nb/Ta–REE (U–B)–Be–Bi–Li–P (Sn–U–As)–B–Be Be–chrysoberyl Sc–Nb/Ta–P Sn–W–As–Pb–Zn–Cu Be–beryl Nb/Ta–Sn–Li (U–Be–B)–mica Be–emerald–kaolin B–tourmaline Be–aquamarine Cs–Li Cs–Nb–Be–W–B–Li–REE F P–B–Be Nb–Be–Li–P F–topaz (F–P–As–Sn–U)–Nb/Ta–B–REE Si–amethyst F–topaz B (U–B–F–Be)–Ta/Nb–Sn–Li Si–rose quartz Be–beryl B–tourmaline graphite B–corundum–prismatine B–tourmaline As–Sn Si–quartz feldspar Li Be–Nb/Ta–B–F–REE Nb/Ta–Be–Li feldspar Be–beryl (Ti–Fe)–B–Be–P Si–quartz ((REE–W)–Be–P–Li–Nb–Ta) nepheline Be–aquamarine Be–emerald F–topaz Be–Si–aquamarine–smoky quartz Si–quartz –amethyst Al–corundum–andalusite Be–beryl F–topaz Feldspar Be–aquamarine Sc–U–REE Rb–Cs–Li–Sn Be –Nb–P–feldspar sodium

Gem site Deposit Gem site Gem site Gem site

448,216 518 448 448 448 470 487 468,520 448 58,487,502,508,509,522 471 448 448,452 522 471 463 448 484,498,547 461,485,491,509,525,526 477 47 498 463 472 469 463,479 463,479 478 469 463 448 523 104 463 435,447 491,5147,518 426,512,516 537,538 472 492 516 448 517,519,521 469 494 519,541 448 448 463 448 469 521 448 463 515 448 525,526,531 440 440,464,481,482,483,515

Deposit Gem site Gem site Deposit Deposit Gem site Gem site Deposit

Deposit Gem site Gem site Gem site Deposit Gem site Gem site Gem site Gem site Deposit Prospect Deposit Deposit Deposit Gem site Gem site Deposit Gem site Gem site Gem site Gem site Gem site Gem site Gem site Deposit Gem site Deposit Large deposit

558

H.G. Dill / Ore Geology Reviews 69 (2015) 417 –561 Table xx (continued)

Table xx

index of terms.

Term

Term

Page

Achaean Achroite Aegirite Aeschynite Agpaitic Alaskite Albite Albitization Albitite Alexandrite Alkaline Allanite Alleghanian Alluaudite “huhnerkobelite” Alpine-type Alumosilicate Amazonite Amblygonite Analcite Anatase Andalusite Andean-type Andradite Apatite Aquamarine Arfvedsonite Arrojadite Arsenic Arsenopyrite Arthurite Asphaltite A-type Audio-magnetotelluric (AMT) Autunite Aventurine Baltica Barbosalite Barite Bassetite Bastnaesite-(Ce) Bastnaesite-(La) Bavenite Bazzite Behoite Benyacarite Beraunite Bermanite Berthierine Bertrandite Beryl Beryllium Beta�te Beudandite Bikitaite Biotite Bismite Bismuth Bismuthinite Bismutomicrolite Bismutotantalite Bityite Bixbite Black shale Bobierrite Boron Boudinage Brasiliano Brazilianite Brochantite Bromellite Brookite Cacoxenite Calcioferrite Calcite

536 473,893 473,524 471 473 475 476 433,449,462,471,472,473,477,502,525,527,541,547 109 532 532 471 485 466 499 520 516 533 518 517 517 445 475 475 469 452 467 510 510 466 523 525 461 453 517 468 466 529 467 473 473 468 468 470 558 520 558 558 463,468,470,492,532 426,431,432,444,448,451 444,448-450,462,463,469 475,476,503 558 519 426,448,460,461,475,476 558 450,489,510-514,534 479,511,513 513 513 468 462,532 529 558 441,455,462,463,476-490,483 46,68,82,120 473,478,537 487,117 558 470 558 558 518 471,476,518,524,525,532

Page

Cancrinite 518 Carbonatite 532,534,536 Carlhintzeite 478 Cassiterite 435,445,447-451,453,454 Cerianite 471,473 Cerianite-(Ce) 473 Cerite 558 Cerussite 558 Cesium 431,441,488,519,534 Chabazite 519 Chalcanthite 558 Chalcedony 517 Chalcocite 558 Chalcophanite 558 Chalcopyrite 558 Chalcosiderite 558 Chamosite 558 Cheralite 475 Chernikovite 558 Chiavennite 519 Chibinite 518 Childrenite 558 Chlorite group 558 Christophite 511 Chrysoberyl 501,532,535 Chrysocolla 562 Churchite-(y) 558 Cleavelandite 470,517,518 Clinopyroxene 514,524 Cof �nite 474 Collinsite 558 COLTAN 506,510,532,534 Columbite-(Fe) 453,475,485,486,502-504,539 Connellite 558 Controlled source audio magnetotelluric (CSAMT) 461 Copper 479,534 Cordierite 461,468,471,475,477,478,501,519 Corundum 519-522,524,535 Corundum (sapphire) 518 Covellite 558 Crandallite 558 Cryolite 473,477,478,530,533 Cryptomelane 524 Cubanite 558 Cuprite 558 Cuprobismutite 558 Cyrilovite 460 Danburite 462,479,480 Davidite 473,474 Davidite-(La) 473 Dessauite 474 Devilline 558 Dewindtite 558 Diadochite 558 Diaspore 521 Dickinsonite 558 Dickite 448,523 Dickite 448,523 Digenite 558 Diopside 475,503,517,523-525 Diopside–hedenbergite 475,525 Diorite 472,479,496,503,521 Djurleite 558 Dravite 38,46,61,62 Dufrénite 558 Dumortierite 462,479,520,554 Durbachite 472 Earlshannonite 558 Eclogite 482,491,515,519 Edingtonite 519 Elbaite 426,454,462,470,477,479,490,491,494 Elpidite 473 Emerald 448,449,462,470-472 Emplectite 558 Endoskarn 449,514 Ensialic 417,424,427,442,443,445,462,463,474

559

H.G. Dill / Ore Geology Reviews 69 (2015) 417 –561 Table xx (continued)

Table xx (continued)

Term

Page

Term

Page

Ensimatic Eosphorite Epidote Epistolite Episyenite Ernstite Euclase Eudialyte Exoskarn Fair�eldite Feldspar Fergusonite Ferriallanite Ferrisicklerite Ferristrunzite Ferrolaueite Ferrostrunzite Florencite Fluellite Fluocerite-(Ce) Fluorellestadite Fluorine Fluoroapatite Foyaite Frondelite Gabbro Gagarinite-(Y) Gahnite Galena Garnet Genthelvite Gibbsite Glass Goethite Gondwana Gorceixite Gordonite Gormanite Goshenite Goyazite Graftonite Grandidierite Granite

509,510,528,529,538 559 518,524 474 418,509,525,539 559 462,470,509 474 449,514 559 102,103,106-110,113,114 426,471,472 559 481,484,485,490 559 559 559 471 559 473 559 533,449,452,463,471,476-480,489 559 474,518 559 435,473,475,476,496,498,500,503 473 432,511,513 451,485,511 478,485,487,488,490,494,502-504 513 559 102,103,115,116,117,118,119 101 425,427,428,468,470,473,478,482,485,487,488,514 559 559 559 462,532,533,559 559 559 559 417,418,420,421-423,431,432,435,437,440-443,445, 447-452,459-463 468,472,477,496,498,519,521,530 420,426,448,491,509,515,525 420,426,448 417,443,506,523,529,536 475 435,440,442,445,447-449,451-453,460,461,463,476 475,525,536 460 525 535 462,532 468 473,476,517,518,533 511 466 469,479 466 519,525 475 474 426,440,470,478,481,485,488,492,494 468 470 467 475 521 469 519 451,473,474,476,502,517,518 523 477 511,513

Isokite Ixiolite Jadeite Jahnsite Jeremejevite Jungite Kaolin Kaolinite Kastningite Keckite Kidwellite Kingsmountite Klippen Knopite Kolbeckite Kornerupine Kosnarite Kryzhanovskite Kunzite Kyanite Lamprophyre Landesite Lapis lazuli Lascas Laueite Laumontite Laurussia Lazulite LCT Lehnerite Lepidolite Leucogranite Leucophosphite Leucosome Lherzolite Libethenite Lipscombite Lithiophilite Lithium

465 500 521 466 462,479 468 507,523,524,536,551 448,507,524 465 466 466 498 461,510,516,519 471 510 462,475 474 466 479,522 492,501,519-521,535 468,469,474 467 535 535 466 519 427,468,482,487 520,533 430-432,441,509,522 467 454,489-491,495,496,516,518,519,533 463 466 515 491 465 466 467 470,481,483-486,488-492,494-496,498,499,510, 522,533 449,451,510 474 474 474 466 474,518 470,474,517 461 465 465 468,475,476,479,490,509,514,517-519,521,522,525 521 518 489,511 521,522 465 461

Granodiorite Graphic Graphic intergrowth Graphite Grayite Greisen Grossularite Hagendor�te Harzburgite Hauyne Heliodor Helvine Hematite Hemimorphite Hentschelite Herderite Heterosite Heulandite Hibonite Hiortdahlite Holmquistite Hopeite Hornblendite Hureaulite Huttonite Hydrogrossular Hydroxyl-herderite Ijolitic Ilmenite Impsonite Indigolite Indium

Loellingite Lomonosovite Loparite Lorenzenite Ludlamite Lujavrite Magnetite Magnetotellurics (MT) Malachite Mangangordonite Marble Margarite Marialite Marmatite Marundite Matulaite Medium-magnetotelluric (MMT) Mejonite Melanosome Messelite Metaautunite Metagraywacke Metallotect Metapegmatite Metasabkha Metaswitzerite Metatorbernite Metavivianite Meurigite-k Miaskitic Mica Mica schist Microcline

518 515 465 467 459,477,479 418,419,445,451,462,469,470,472,473,475,477,478, 479,480,486,487,488,492,494,500,506,512,529 418,420,426,427,434,435,442,443,472,480,487,494, 499,501,502 518 467 467 520 466 473,474 500,501,503,504,506-508,514-516,518,522,523,525 448,468,479,485,490,492,507,523 451,496,514,516,518

560




Term

Page

Term

Page

Microlite Migmatite Milky quartz Mitridatite Moldanubian Molybdenite Molybdenum Monazite Montebrasite Montgomeryite Moonstone Morganite Morinite Mosandrite Mrázekite Mullite Murmanite Muscovite

426,478,500,513,534 418,426,461,472,473,479,501,515,518,520,523,538 495,517 465 518-521,531 426,448,489,511,514 510,512,514,518,529,534 543,471-476,482,516,532 479,481,484,485,488,490,491,494,496,533 465 517 444,462,471,518,532 465 474 465 535 474 475,477-479,481-483,486,490,496,502,504, 507,514-516 523 465

Pyromorphite Pyrrhotite Quartz Quartzite Rapakivi granite Reactivation

467 468,503,514,529,530 496,498,503,504,506,507,509,514-518,520-526,529 426,451,459,479,518,520,521,526,537 452,472 424,442,443,445,469,483,485,499,510,512,530, 531,538 467 417,418,426,431,433,434,439,442,443,451,452,453, 468,470,471,472,473,474,475,476,477,479,480,494, 496,499,500,501,502,509,510,513,514,519,521,522, 525,527,530,532,533,534,539,541,542,543,544,545, 547,548,552,553,554,555,556,557 477,481,529 442,452,460,478,517 462,476 417,442,443,470,471,473,481,482,496,514,530, 538,539 417,445,462,470,514,530 474 467 467 520 469 443 462 462,477,478,479,495 488 488,495,533,534 451,492,502,503,510,517,518 467 467 473,509 473 518 475 466 445,469,477,480-482,484,485,489,490,496,499, 501,502,509 500,508-510,526,534 514,517,518,521,523,524,535 435,445,448,449,461,462,475,492,521,525,530-532 426,436,449,485,515,518,519,527 468 468 454,459,461,477-479,485,503,520 510,511 533 465 501,519,520 481,484,485,490,494 460,529 426,431,436,449,468,475,477,480,501,512, 513,519,520 529 521-525,529-531,535-537,539 500,518,535 466 426,481,483,485,503,522,536 432,468,477,485,489,503,511,513,514,525 473,474,517 475,511,513,521,535 420,426,439,440,443,451,462,469,470,473,478, 479,481,484 466 453,531, 511,513,519,520,521, 474 519 466 511,529 519 435,445,448,477,478,527 466 466 417,431,443,449,451,462,480,488,539

Nacrite Natrodufrenite (+dufrenite) Natrolite Nepheline Nepheline syenite Neptunite Nigrine Ningyoite Niobium Nordgauite NYF Ongonite Opal Orthite Orthoclase Oxiberaunite Pachnolite Pan-African Parahopeite Paraiba tourmaline Parascholzite Paravauxite Parsonsite Paulkerrite Pegmatoid Peralkaline Perlof �te Perovskite Petalite Phenakite Phillipsite Phlogopite Phosphoferrite Phosphophyllite Phosphorite Phosphoscorodite Phosphosiderite Placer Plumasite Pollucite Porphyry Post-kinematic Pre-kinematic Proterozoic Protolithionite Protore Pseudolaueite Pseudomalachite Pseudopegmatite Purpurite Pyrite Pyrobitumen Pyrochlore

519,523 519,523,530,535,538 452,472,473,474,500,518,530,535 474 468,487,502-504,506,507,513,517,518 471,475 443,450,474,500,509,517,518,534 465 430-432,470,509,522 460 503,517 474,515 486,514-516,517,523 466 478 428,473,475,476,478,479,486,487,506,523 468 426,454,459,477,479,524,528,533 468 466 468 467 417,418,420,426,427,434-436,442,443,441, 477-479,482, 483,485 462,473,474,476,506,530 466 474,530 451,495,496,533,534 468,470,492 519 443,470,475,514,517,523,536 466 533 477,488,533 511 466 418,473,487,503,504,522,531,532,534-536 521,522 443,482,488,495,496,519 448,514,517,529,534 472,486,502 420,435 506,518,521,522 448 476,531 466 465 417,418,420,426,435,438,440,442,483-485,492,494, 537-539 467 435,448,4489,451,453,472,489,510,511,529,530 523 468,473-476,485,500,503,504,513,530,533,534

Reddingite REE/ rare earth elements

Rhenohercynian Rhyolite Riebeckite Rift Rift-type Rinkite Rittmannite Robertsite Rockbridgeite Roscherite Rose quartz Rosterite Rubellite Rubicline Rubidium Rutile Sabugalite Saleeite Samarskite Samarskite-(Y) Santabarbaraite Sapphirine Sarcopside Saxo-Thuringian Scandium Scapolite Scheelite Schlieren Scholzite Schoonerite Schorl Scorodite Scorzalite Segelerite Sekaninaite Sicklerite Siderite Sillimanite Silver Skarn Sodalite Souzalite Spessartite Sphalerite Sphene Spinel Spodumene Stanĕkite Stannite Staurolite Steenstrupin Stellerite Stewartite Stibnite Stilbite Stockscheider Strengite Strunzite S-type

Dill, (2015) - Pegmatites y Aplites

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