Spherocobaltite
Spherocobaltite or sphaerocobaltite is a cobalt carbonate mineral with chemical composition CoCO3. In its (rare) pure form, it is typically a rose-red color, but impure specimens can be shades of pink to pale brown. It crystallizes in the trigonal crystal system.
| Spherocobaltite | |
|---|---|
| General | |
| Category | Carbonate mineral |
| Formula (repeating unit) | CoCO3 |
| IMA symbol | Scbt |
| Strunz classification | 5.AB.05 |
| Crystal system | Trigonal |
| Crystal class | Hexagonal scalenohedral (3m) H-M symbol: (3 2/m) |
| Space group | R3c |
| Unit cell | a = 4.65, c = 14.95 [Å]; Z = 6 |
| Identification | |
| Formula mass | 118.94 g/mol |
| Color | Most commonly dark magenta red; pink to red, brown, brownish red, grey, greyish red, velvet-black (due to surface alteration) |
| Crystal habit | Encrustations - forms crust-like aggregates on matrix, crystals uncommon: rhombohedral to discoidal |
| Cleavage | Perfect rhomboidal cleavage |
| Mohs scale hardness | 4 |
| Luster | Vitreous |
| Streak | Pink |
| Diaphaneity | Transparent to translucent |
| Specific gravity | 4.13 |
| Optical properties | Uniaxial (–) |
| Refractive index | nε = 1.600, nω = 1.885 |
| Birefringence | 0.285 |
| Pleochroism | Dichroic: O = violet-red; E = rose-red |
| References | |
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