Purpurite is a manganese phosphate mineral with the formula MnPO4, with varying amounts of iron depending upon its source. It occurs in color ranges from brownish black via purple and violet to dark red.[3]
| Purpurite | |
|---|---|
Purpurite from Namibia
| |
| General | |
| Category | Phosphate minerals |
| Formula (repeating unit) | Mn3+PO4 |
| IMA symbol | Pur[1] |
| Strunz classification | 8.AB.10 |
| Crystal system | Orthorhombic |
| Crystal class | Dipyramidal (mmm) H-M symbol: (2/m 2/m 2/m) |
| Space group | Pnmb |
| Identification | |
| Formula mass | 149.91 g/mol |
| Color | Brownish black, violet, dark pink, dark red, reddish purple |
| Crystal habit | Massive to granular |
| Cleavage | [100] [001] perfect |
| Fracture | Uneven |
| Tenacity | Brittle |
| Mohs scale hardness | 4–5 |
| Luster | Earthy |
| Streak | red |
| Specific gravity | 3.2 – 3.4 |
| Optical properties | Biaxial (+) |
| Refractive index | nα = 1.850(2) nβ = 1.860(2) nγ = 1.920(2) |
| Birefringence | δ = 0.070 |
| 2V angle | 38° |
| References | [2][3][4] |
Purpurite forms a series with the iron-bearing endmember heterosite, FePO4.[4]
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