Canfieldite is a rare

silver Silver is a chemical element; it has Symbol (chemistry), symbol Ag () and atomic number 47. A soft, whitish-gray, lustrous transition metal, it exhibits the highest electrical conductivity, thermal conductivity, and reflectivity of any metal. ...

tin

sulfide Sulfide (also sulphide in British English) is an inorganic anion of sulfur with the chemical formula S2− or a compound containing one or more S2− ions. Solutions of sulfide salts are corrosive. ''Sulfide'' also refers to large families o ...

mineral with formula: Ag₈SnS₆. The mineral typically contains variable amounts of

germanium Germanium is a chemical element; it has Symbol (chemistry), symbol Ge and atomic number 32. It is lustrous, hard-brittle, grayish-white and similar in appearance to silicon. It is a metalloid or a nonmetal in the carbon group that is chemically ...

substitution in the tin site and

tellurium Tellurium is a chemical element; it has symbol Te and atomic number 52. It is a brittle, mildly toxic, rare, silver-white metalloid. Tellurium is chemically related to selenium and sulfur, all three of which are chalcogens. It is occasionally fou ...

in the sulfur site. There is a complete series between canfieldite and its germanium analogue,

argyrodite Argyrodite is an uncommon silver germanium sulfide mineral with formula Ag8GeS6. The color is iron-black with a purplish tinge, and the luster metallic. Discovered and named by Albin Weisbach in 1886, it is of interest as it was the material fro ...

. It forms black

orthorhombic In crystallography, the orthorhombic crystal system is one of the 7 crystal systems. Orthorhombic Lattice (group), lattices result from stretching a cubic crystal system, cubic lattice along two of its orthogonal pairs by two different factors, res ...

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 The Mohs scale ( ) of mineral hardness is a qualitative ordinal scale, from 1 to 10, characterizing scratch resistance of mineral In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid substance with a fair ...

is 2.5 and the

specific gravity Relative density, also called specific gravity, is a dimensionless quantity defined as the ratio of the density (mass of a unit volume) of a substance to the density of a given reference material. Specific gravity for solids and liquids is nea ...

is 6.28. Canfieldite exhibits conchoidal fracturing and no cleavage. Canfieldite was first described in 1893 from an occurrence in Colquechaca,

Potosí Potosí, known as Villa Imperial de Potosí in the colonial period, is the capital city and a municipality of the Potosí Department, Department of Potosí in Bolivia. It is one of the list of highest cities in the world, highest cities in the wo ...

Department,

Bolivia Bolivia, officially the Plurinational State of Bolivia, is a landlocked country located in central South America. The country features diverse geography, including vast Amazonian plains, tropical lowlands, mountains, the Gran Chaco Province, w ...

. It was named for Frederick Alexander Canfield (1849–1926), an American mining engineer.

References

Silver minerals Tin minerals Sulfide minerals Orthorhombic minerals Minerals in space group 33 {{Sulfide-mineral-stub

See also

References