Brushite
Brushite is a phosphate mineral with the chemical formula CaHPO4·2H2O. Crystals of the pure compound belong to the monoclinic space group C2/c and are colorless. It is the phosphate analogue of the arsenate pharmacolite.
| Brushite | |
|---|---|
Brushite (white) on montmorillonite | |
| General | |
| Category | Phosphate mineral |
| Formula (repeating unit) | CaHPO4 · 2 H2O |
| IMA symbol | Bsh |
| Strunz classification | 8.CJ.50 |
| Crystal system | Monoclinic |
| Space group | Ia (no. 9) |
| Unit cell | a = 6.265 Å, b = 15.19 Å, c = 5.814 Å; β = 116.47°; Z = 4 |
| Identification | |
| Color | Colorless to pale or ivory-yellow |
| Crystal habit | Prismatic to tabular acicular crystals; typically powdery or earthy |
| Cleavage | Perfect on {010} and {001} |
| Tenacity | Brittle |
| Mohs scale hardness | 2.5 |
| Luster | Vitreous, pearly on cleavages |
| Diaphaneity | Transparent to translucent |
| Specific gravity | 2.328 |
| Optical properties | Biaxial (+) |
| Refractive index | nα = 1.539 – 1.540 nβ = 1.544 – 1.546 nγ = 1.551 – 1.552 |
| Birefringence | δ = 0.012 |
| 2V angle | Measured: 59 to 87° |
| Solubility | Readily in HCl |
| Other characteristics | Piezoelectric |
| References | |
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