Golden brown metallic microcrystals of the extremely rare tin sulphide mineral ottemannite from one of the few known localities worldwide: Forestville, Schuylkill County, Pennsylvania, United States of America. Outstanding and very rich specimen for size the quality. Ex Vandenbroucke Museum collection specimen, from Waregem, Belgium. — Photo: David Hospital · CC BY-SA 4.0
Ottemannite
Ottemannite is an IMA-recognized mineral species in the sulfide class, with the chemical formula Sn₂S₃.
It crystallizes in the orthorhombic crystal system (space group Pnma).
Key properties: Mohs hardness 2; specific gravity 4.87; Metallic luster.
IMA symbol Ott, IMA status: approved, named in 1966.
Found in zones of oxidation or secondary enrichment in hydrothermal tin deposits.
It is found associated with Stannite, cassiterite, herzenbergite, berndtite.
The mineral was named to honor Joachim Ottemann (1914–), German mineralogist, Heidelberg, Germany.