Algodonite: Mohawk Mine, Keweenaw Peninsula, Michigan (each – 1 inch across). Photo © Joel E. Arem, PhD, FGA. Used with permission.
Cabochons of these arsenides are bright, silvery, and metallic and are both attractive and unusual. However, they tarnish rather quickly and the surfaces turn a drab brown and lose their luster. Cut stones are rarely seen even in collections, although they are strikingly beautiful when cut and polished to a high luster. They must be sprayed with lacquer to prevent tarnishing. Algodonite and domeykite are heat sensitive, and care must be exercised in cutting.
Algodonite Value
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Algodonite Information
| Data | Value |
| Name | Algodonite |
| Crystallography | Hexagonal crystals rare; usually massive, granular, reniforn. Domeykite is isometric. |
| Colors | Silver white to steel gray; tarnishes rapidly to a dull brown. |
| Luster | Metallic; opaque. |
| Hardness | 3-4 (Domeykite: 3-3.5). |
| Density | 8.38 (Domeykite: 7.92-8.10). |
| Cleavage | None. Fracture uneven in domeykite, subconchoidal in algodonite. |
| Stone Sizes | Cabochons could be cut to almost any size, depending on the availability of large masses of metallic rough. |
| Formula | Cu6As (Domeykite = Cu3As). |
Occurrence: Localities that produce copper arsenide minerals.
Algodonite from Painsdale, Michigan, in fine crystals. In masses from the Algodones Mines, Coquimbo, Chile, and Cerro de Los Aeguas, Rancagua, Chile.
Mohawkite is a mixture of algodonite and other copper arsenides, from the Mohawk Mine, Keweenaw Peninsula, Michigan.
Domeykite is from the Mohawk Mine, Michigan; Lake Superior district, Ontario, Canada: Guererro, Mexico; also from Chile, Germany, Sweden, and from Cornwall, England. Related minerals are found at Beloves, Czechoslovakia, and Mesanki, Iran.
Comments: Cabochons of these arsenides are bright, silvery, and metallic and are both attractive and unusual. However, they tarnish rather quickly and the surfaces turn a drab brown and lose their luster. Cut stones are rarely seen even in collections, although they are strikingly beautiful when cut and polished to a high luster. They must be sprayed with lacquer to prevent tarnishing. Algodonite and domeykite are heat sensitive, and care must be exercised in cutting.
Name: After he Algodones Mines, Coquimbo, Chile.
