Variscite
Variscite is a hydrated aluminium phosphate mineral (AlPO4·2H2O). It is a relatively rare phosphate mineral. It is sometimes confused with turquoise; however, variscite is usually greener in color. The green color results from the presence of small amounts of trivalent chromium (Cr3+
).
| Variscite | |
|---|---|
| General | |
| Category | Phosphate minerals |
| Formula (repeating unit) | AlPO4·2H2O |
| IMA symbol | Var |
| Strunz classification | 8.CD.10 |
| Crystal system | Orthorhombic |
| Crystal class | Dipyramidal (mmm) H-M symbol: (2/m 2/m 2/m) |
| Space group | Pbca |
| Identification | |
| Color | Pale to emerald-green (pale green in transmitted light), green, blue green, yellow green, pale shades of brown or yellow, rarely red and colourless to white |
| Crystal habit | Encrustations and reniform masses |
| Cleavage | [010] perfect |
| Fracture | Conchoidal to splintery |
| Mohs scale hardness | 4.5 |
| Luster | Vitreous to waxy |
| Streak | White |
| Diaphaneity | Transparent to translucent |
| Specific gravity | 2.57 to 2.61 |
| Optical properties | Biaxial (−) |
| Refractive index | nα = 1.563 nβ = 1.588 nγ = 1.594 |
| Birefringence | δ = 0.031 |
| References | |
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