Alloclasite
Sulfosalt mineral
From Wikipedia, the free encyclopedia
Alloclasite, or (Co,Fe)AsS, is a sulfosalt mineral (IMA symbol: Acl).[1] It is a member of the arsenopyrite group. Alloclasite crystallizes in the monoclinic system and typically forms as columnar to radiating acicular prismatic clusters. It is an opaque steel-gray to silver-white, with a metallic luster and a black streak. It is brittle with perfect cleavage, a Mohs hardness of 5 and a specific gravity of 5.91–5.95.[2]
| Alloclasite | |
|---|---|
| General | |
| Category | Minerals |
| Formula | (Co,Fe)AsS |
| IMA symbol | All |
| Identification | |
| Color | Steel gray to silver |
| Fracture | Irregular/Uneven, Sub-Conchoidal |
| Mohs scale hardness | 5 |
| Luster | Metallic |
| Streak | Nearly black |
| Diaphaneity | Opaque |
| Specific gravity | 5.95 |
It was first described in 1866 for an occurrence in Romania.[3] Its name is derived from Greek for "other" and "to break," in reference to its distinct cleavage which distinguished it from the similar appearing mineral marcasite.[4][2]
The mineral is monoclinic in the P21 space group.[5]
