Mineralogy and Petrology (1998) 63:199-222 Mineralogy RFIO Petrology © Springer-Verlag 1998 Printed in Austria Tantalum mineralization in the apical part of the Cinovec (Zinnwald) granite stock A. K. Rub ~, M. Stemprok 2, and M. G. Rub 3 1VIMS (All Russia Scientific Institute of Mineral Resources), Moscow, Russia 2 Faculty of Science, Charles University, Prague, Czech Republic 3 IGEM (Institute of the Geology of Ore Deposits, Petrology, Mineralogy and Geochemistry), Academy of Sciences, Moscow, Russia With 11 Figures Received September 10, 1996; revised version accepted April 27, 1998 Summary Granite-hosted tantalum mineralization was studied in the apical part of the C~novec (Zinnwald) granite stock (eastern Kru~n~ hory, Czech Republic). Samples of granite and greisen from drill hole CS-1 (1596m deep), situated in the centre of the granite body were analysed chemically and examined by electron microprobe. The apical, mainly lepidolite granite with 24 to 212ppm Ta contains Ta-rich Mn columbite, uranmicrolite and strneverite (tantalian rutile). During greisenization the contents of Ta decreased or remained the same, but the newly formed cassiterite has elevated contents of Ta, probably due to remobilization from albitized granites. Niobium and tantalum mineralization can be linked with both magmatic and postmagmatic stages of granite evolution. Ta-rich columbite formed as a result of albitization dominant at the top of the granite cupola, whereas magmatic Nb-rich columbite is present throughout the entire profile of the granite stock. The Cinovec granite stock is similar to some Palaeozoic Ta-bearing granite stocks in the Far East of Russia (Vosnesenka, Pogranichnyi) which are characterized by a vertical sequence of lepidolite, zinnwaldite and protolithionite granites. It shows minor similarities with Mesozoic amazonite-bearing granites in Transbaikalia (Etyka, Orlovka) and differs petrologically and mineralogically from the Palaeozoic lepidolite granite of Beauvoir (Echassieres) in France. Zusammenfassung Tantalvererzung im oberen TeiI des Cfnovec (Zinnwalder) Granitstocks Eine granitgebundene Tantalvererzung wurde im oberen Teil des Cfnovec (Zinnwalder) Granitstocks (6stliches Erzgebirge, Tschechische Republik) untersucht. Granit- und