Polybasite | |
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Locality: Arizpe, Sonora, Mexico. Scale bar is one inch (2.5 cm.) |
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General | |
Category | Sulfosalt minerals |
Chemical formula | [(Ag,Cu)6(Sb,As)2S7][Ag9CuS4] |
Strunz classification | 02.GB.15 |
Identification | |
Colour | steel black |
Crystal system | monoclinic |
Cleavage | poor on (001) |
Fracture | uneven |
Mohs scale hardness | 1.5-2 |
Luster | metallic, adamantine or glimmering |
Streak | black with reddish tint |
Specific gravity | 6-6.2 |
References | [1][2][3][4] |
Polybasite is a sulfosalt mineral of silver, copper, antimony and arsenic. Its chemical formula is [(Ag,Cu)6(Sb,As)2S7][Ag9CuS4].
It forms black monoclinic crystals (thin, tabular, with six corners) which can show dark red internal reflections. It has a Mohs hardness of 2.5 to 3. It is found worldwide and is an ore of silver. The name comes from the number of base metals in the mineral.