Canfieldite

Canfieldite

Canfieldite
General
Category Sulfide minerals
Formula
(repeating unit)		 Ag8SnS6
Strunz classification 02.BA.70
Crystal system Orthorhombic
Identification
Color Steel gray with reddish tint
Fracture Irregular/ uneven, conchoidal
Tenacity Brittle
Mohs scale hardness 2½
Luster Metallic
Streak Greyish black
Diaphaneity Opaque
Density 6.2 - 6.3 g/cm3

Canfieldite is a rare silver tin sulfide mineral with formula: Ag8SnS6. The mineral typically contains variable amounts of germanium substitution in the tin site and tellurium in the sulfur site. There is a complete series between canfieldite and its germanium analogue, argyrodite. It forms black orthorhombic crystals which often appear to be cubic in form due to twinning. The most typical form is as botryoidal rounded grape-like masses. Its Mohs hardness is 2.5 and the specific gravity is 6.28. Canfieldite exhibits conchoidal fracturing and no cleavage.

Canfieldite was first described in 1893 from an occurrence in Colquechaca, Potosí Department, Bolivia. It was named for Frederick Alexander Canfield (1849–1926), an American mining engineer.

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References

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