Stangersite, a new tin germanium sulfide, from the Kateřina mine, Radvanice near Trutnov, Czech Republic

The new mineral stangersite was found in the burning waste dump of abandoned Kateřina coal mine at Radvanice near Trutnov, northern Bohemia, Czech Republic. The new mineral occurs as well-formed, flattened, acicular crystals with a cross-section of 2–5 × 20–40 μm and up to 1 cm in length. They constitute random or fan-shaped clusters on rock fragments and on crumbly black ash in association with greenockite, herzenbergite, unnamed GeS 2 and GeAsS. Stangersite was also observed as irregular grains, up to 100 μm in size, in the multicomponent aggregates on which the above-described crystals grow. These aggregates are formed, beside stangersite, by minerals of Bi–Sb, Bi 2 S 3 –Sb 2 S 3 and Bi 2 S 3 –Bi 2 Se 3 solid solutions, Bi 3 S 2 , Bi-sulfo/seleno/tellurides, tellurium, unnamed PbGeS 3 , Cd 4 GeS 6 , GeAsS, GeS 2 , Sn 5 Sb 3 S 7 , greenockite, cadmoindite, herzenbergite, teallite and Sn- and/or Se-bearing galena. Stangersite formed under reducing conditions by direct crystallization from hot gasses (250–350 °C) containing Cl and F, at a depth of 30–60 cm under the surface of the (100) layers of Sn 2+ S 5 coordination pyramids and with interspaces filled by lone electron pairs of Sn 2+ and [001] chains of Ge 4+ S 4 coordination tetrahedra. The Raman spectrum of stangersite with tentative band assignments is given. We named the mineral after its chemical constituents: Sn ( stan num), Ge ( ger manium) and S ( s ulphur).