Nickeline
| Nickeline | |
|---|---|
| General | |
| Category | Arsenide mineral |
| Formula | nickel arsenide (NiAs) |
| IMA symbol | Nc |
| Strunz classification | 2.CC.05 |
| Crystal system | Hexagonal |
| Crystal class | Dihexagonal dipyramidal (6/mmm) H-M symbol: (6/m 2/m 2/m) |
| Space group | P63/mmc |
| Unit cell | a = 3.602 Å, c = 5.009 Å; Z = 2 |
| Identification | |
| Color | Pale copper red with blackish tarnish. white with strong yellowish pink hue on polished section strongly anisotropic |
| Crystal habit | Massive columnar to reniform, rarely as distorted, horizontally striated, {1011} terminated crystals |
| Twinning | On {1011} producing fourlings |
| Cleavage | {1010} Imperfect, {0001} Imperfect |
| Fracture | Conchoidal |
| Tenacity | Brittle |
| Mohs scale hardness | 5 – 5.5 |
| Luster | metallic |
| Streak | brownish black |
| Diaphaneity | Opaque |
| Specific gravity | 7.8 |
| Pleochroism | Strong (reflected light) |
| Fusibility | 2 |
| Other characteristics | garlic odor on heating |
| References | |
Nickeline or niccolite is the mineral form of nickel arsenide. The naturally-occurring mineral contains roughly 43.9% nickel and 56.1% arsenic by mass, but composition of the mineral may vary slightly.
Small quantities of sulfur, iron and cobalt are usually present, and sometimes the arsenic is largely replaced by antimony. This last forms an isomorphous series with breithauptite (nickel antimonide).