Sicherite

sicherite

hutchinsonite

hatchite

jentschite

Images

Formula: TlAg2(As,Sb)3S6
Sulphosalt, thallium-, silver-, arsenic- and antimony- bearing mineral
Crystal System: Orthorhombic
Specific gravity: 5.26 calculated
Hardness: 3
Streak: Dark brown-red
Colour: Dark grey, black
Environments

Metamorphic environments
Hydrothermal environments

Localities

At the type locality, the Lengenbach Quarry, Fäld, Binn, Goms, Valais, Switzerland, sicherite occurs in small cavities in a dolomitic rock, associated with abundant realgar and various other sulphosalts, mainly thallium-bearing species such as hutchinsonite, hatchite and jentschite.
Individual crystals of sicherite reach approximately 0.4 mm, but aggregates may exceed 1–2 mm. Sicherite, as well as the other thallium minerals in Lengenbach, presumably represent products of a late stage activity of thallium- and arsenic- bearing hydrothermal solutions during metamorphism (AM 86.1087-1093).
Gabrielite is another thallium-bearing mineral found at this locality, visually indistinguishable from sicherite (CM 44.135-140).

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