Outstanding shiny single crystal of the very rare mineral sulphotsumoite. From Ergelyakh Deposit, Indigirka River Basin, Sakha Republic, Russian Federation. Ex Vandenbroucke Museum collection from Waregem, Belgium. — Photo: David Hospital · CC BY-SA 4.0
Sulphotsumoite
Sulphotsumoite is an IMA-recognized mineral species in the sulfide class, with the chemical formula Bi₃Te₂S.
It crystallizes in the hexagonal crystal system (space group P-3m1). It is a member of the Tetradymite structural group.
Key properties: specific gravity 8.13; Metallic. R1 –R2: (400) —, (420) 51.8–53.8, (440) 51.8–54.1, (460) 52.0–54.7, (480) 52.3–55.3, (500) 52.7–56.0 luster.
IMA symbol Stsm, IMA status: approved, named in 1980.
Of hydrothermal origin, with other bismuth tellurides.
It is found associated with Tsumoite, joséite-B.
In allusion to the chemical relation to tsumoite.