Canfieldite is a rare

silver Silver is a chemical element with the Symbol (chemistry), symbol Ag (from the Latin ', derived from the Proto-Indo-European wikt:Reconstruction:Proto-Indo-European/h₂erǵ-, ''h₂erǵ'': "shiny" or "white") and atomic number 47. A soft, whi ...

tin Tin is a chemical element with the symbol Sn (from la, stannum) and atomic number 50. Tin is a silvery-coloured metal. Tin is soft enough to be cut with little force and a bar of tin can be bent by hand with little effort. When bent, t ...

sulfide Sulfide (British English also sulphide) 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 chemical compounds lar ...

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

germanium Germanium is a chemical element with the symbol Ge and atomic number 32. It is lustrous, hard-brittle, grayish-white and similar in appearance to silicon. It is a metalloid in the carbon group that is chemically similar to its group neighbors s ...

substitution in the tin site and

tellurium Tellurium is a chemical element with the 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 by Clemens Winkler in 1886, it is of interest as it was described shortly after t ...

. 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 The Mohs scale of mineral hardness () is a qualitative ordinal scale, from 1 to 10, characterizing scratch resistance of various minerals through the ability of harder material to scratch softer material. The scale was introduced in 1812 by th ...

is 2.5 and the

specific gravity Relative density, or specific gravity, is the ratio of the density (mass of a unit volume) of a substance to the density of a given reference material. Specific gravity for liquids is nearly always measured with respect to water (molecule), wa ...

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 Department of Potosí in Bolivia. It is one of the highest cities in the world at a nominal . For centuries, it was the location o ...

Department,

Bolivia , image_flag = Bandera de Bolivia (Estado).svg , flag_alt = Horizontal tricolor (red, yellow, and green from top to bottom) with the coat of arms of Bolivia in the center , flag_alt2 = 7 × 7 square p ...

. It was named for

Frederick Alexander Canfield Frederick may refer to: People * Frederick (given name), the name Nobility Anhalt-Harzgerode *Frederick, Prince of Anhalt-Harzgerode (1613–1670) Austria * Frederick I, Duke of Austria (Babenberg), Duke of Austria from 1195 to 1198 * Frederi ...

(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