Altenberg
Other Names:
District: Bogemian Massif
Commodities : Tin
Altenberg is located in Saxony, Germany, approximately 40 km south of Dresden, near the Czech border. Altenberg is the largest tin deposit in the Erzgebirge and as famous as Cinovec/Zinnwald. The richest ore shoots were mined early in its history, but known production and remaining resources are estimated to be ~50 Mt @ 0.3% Sn. 0.244% Rb, 0.185% Li, and 117 g/t Bi.Mining commenced with the discovery of alluvial cassiterite and higher grade tin veins in 1440, which were selectively mined. Large volume exploitation of the Zwitter greissen commenced shortly afterwards. It contained a dense stockwork of moderate- to low-grade quartz-cassiterite veinlets and disseminations and can, perhaps, lay claim to being the world's first 'bulk mined' orebody. In 1620 a major roof collapse in large, poorly supported stopes led to underground extraction of the fractured material, which thereafter continued to be the principal method of mining at Altenberg. The glory hole which developed, known locally as Pinge, still exists and was, until recently, a tourist attraction but has now been fenced, and is impossible to approach . The existing, relatively modern, mine was run at a loss under the German Democratic Republic. It closed in the 1990s and has been partly rehabilitated and developed as a tourist attraction.
Geologically, Altenberg consists of a suite of several epizonal stocks, cupolas, ring dykes and dykes of an increasingly evolved Late Carboniferous peraluminous granite which is related to the 'Erzgebirge' Granite. These intrusions, together with the older and less evolved Gebirge Granite, underlie much of the Erzgebirge. The intrusions were emplaced partly into subaerial rhyolites and porphyries of the Teplice Caldera, and partly into basement of Neoproterozoic gneiss-to-migmatite. The volatile-rich Altenberg Stock underwent significant autometasomatic Na-, K- and Li-alteration (albitisation, K-feldspathisation, and the formation of Li-micas) to form an apogranite with outer stockscheider (aplite/pegmatite marginal zone). It also produced a large greisen body of cassiterite-rich quartz, topaz and Li-biotite. The greisen body and adjacent zones were overprinted by lower-temperature, late stage, chlorite, hematite and kaolinite.
October 2003
