Polybasite
| Polybasite | |
|---|---|
|
| |
| General | |
| Category | Sulfosalt minerals |
| Formula (repeating unit) | [(Ag,Cu)6(Sb,As)2S7][Ag9CuS4] |
| Strunz classification | 2.GB.15 |
| Crystal system | Monoclinic and trigonal polytypes |
| Crystal class |
Prismatic (2/m) (same H-M symbol) |
| Space group | C2/c |
| Identification | |
| Colour | steel black |
| Cleavage | poor on (001) |
| Fracture | uneven |
| Mohs scale hardness | 1.5-2 |
| Lustre | 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.
References
- ↑ Polybasite: mindat.org
- ↑ Webmineral.com
- ↑ Handbook of Mineralogy
- ↑ Rudolf Dǔd'a and Luboš Rejl (1990). Minerals of the World. Arch Cape Press. p. 40. ISBN 0-517-68030-0.
Unusual polybasite specimen from Mayo Mining District, Yukon Territory, Canada. Size 3.0 x 2.2 x 1.3 cm.
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