Sadisdorf, Schmiedeberg, Erzgebirge, Saxony, Germany

Breccia-pipe related porphyry tin mineralization within a caldera setting (Teplice-Altenberg caldera). The deposit is related to a structurally-complicated cataclasite and sub-volcanic complex, located within Proterozoic gneisses at the intersection of a NNW-trending cataclasis zone and a NE-trending brittle fracture zone. The centre is formed by a multiple intrusion of tin granite into a large fluid explosive breccia. The polymict cataclasite forms a large central body, and also occurs along granite contacts (in the form of mantle breccia) and as a small stock-like breccia body. It contains angular fragments and blocks of various gneisses, remobilized quartz, metagneiss greisen, and gneisses greisenized by multi-stage veinlets and veins. The formation of the cataclasite preceded the sub-volcanic intrusives, but the emplacement of both was connected with multiple metasomatic processes. As a consequence, a large number of different metasomatic and mineralization types occurred in the deposit.

Mining in the area started before 1500 and continued intermittently until 1954. The deposit was first worked for tin and copper, later also for tungsten, molybdenum and bismuth. Intensive ancient mining activities are evident from numerous dumps, pits and subsidences ("Pingen"). The most important outcrop is the "Kupfergrübner Pinge", which was formed in the 17th/18th century by the collapse of sub-surface cavities in the area of a high-grade ore body.

References:
- Palache, C., Berman, H., & Frondel, C. (1951), The System of Mineralogy of James Dwight Dana and Edward Salisbury Dana, Yale University 1837-1892, Volume II: 1016.
- Kolitsch, U., T. Witzke & S. Weiß (1997): Die Mineralien von Sadisdorf, Sächsisches Erzgebirge, Lapis 22(2), 13-32; 54. (in German)
- Breiter, K., Förster, H.-J., and Seltmann, R. (1999): Variscan silicic magmatism and related tin-tungsten mineralization in the Erzgebirge-Slavkovský les metallogenic province. Mineralium Deposita 34, 505-521.