Polydymite
Polydymite, Ni2+Ni23+S4, is a supergene thiospinel sulfide mineral associated with the weathering of primary pentlandite nickel sulfide.
| Polydymite | |
|---|---|
| General | |
| Category | Sulfide mineral Thiospinel group Spinel structural group |
| Formula (repeating unit) | Ni3S4 |
| IMA symbol | Pld |
| Strunz classification | 2.DA.05 |
| Crystal system | Cubic |
| Crystal class | Hexoctahedral (m3m) H-M symbol: (4/m 3 2/m) |
| Space group | Fd3m |
| Unit cell | a = 9.48 Å; Z = 8 |
| Identification | |
| Color | Pale to steel-gray |
| Crystal habit | As octahedral crystals, massive, granular to compact |
| Twinning | Twinning on {111} |
| Cleavage | Indistinct on {001} |
| Fracture | Conchoidal to uneven |
| Mohs scale hardness | 4.5 – 5.5 |
| Luster | Metallic |
| Streak | Black gray |
| Diaphaneity | Opaque |
| Specific gravity | 4.5 – 4.8 |
| Alters to | Tarnishes to copper-red |
| References | |
Polydymite crystallises in the isometric system, with a hardness of 4.5 to 5.5 and a specific gravity of about 4, is dark violet gray to copper-red, often with verdigris and patina from associated copper and arsenic sulfides, and is typically in amorphous to massive infill of lower saprolite ultramafic lithologies.
Polydymite is the nickel equivalent of violarite and in many cases these two minerals are formed together, potentially in solid solution.
Common contaminants of polydymite are cobalt and iron. Polydymite forms a series with linnaeite, Co+2Co+32S4.
This article is issued from Wikipedia. The text is licensed under Creative Commons - Attribution - Sharealike. Additional terms may apply for the media files.