Tarbuttite
| Tarbuttite | |
|---|---|
Tarbuttite from Broken Hill mine (Kabwe mine) in Central Province, Zambia | |
| General | |
| Category | Phosphate minerals |
| Formula | Zn2(PO4)(OH) |
| IMA symbol | Tbt |
| Strunz classification | 8.BB.35 |
| Dana classification | 41.6.7.1 |
| Crystal system | Triclinic |
| Crystal class | Pinacoidal (1) (same H-M symbol) |
| Space group | P1 |
| Unit cell | a = 5.400 Å, b = 5.654 Å c = 6.465 Å, α = 102.51° β = 102.46°, γ = 86.50° Z = 2 |
| Identification | |
| Color | White, colorless, yellow, red, green, or brown |
| Crystal habit | Equant to short prismatic [001], sheaf-like aggregates, crusts, individual crystals rounded and deeply striated |
| Cleavage | Perfect on {010} |
| Fracture | Irregular, uneven |
| Mohs scale hardness | 3.5 |
| Luster | Vitreous, pearly on cleavages |
| Streak | White |
| Diaphaneity | Transparent, translucent |
| Specific gravity | 4.12; 4.19 (calc.) |
| Density | 4.12 g/cm3 (measured) |
| Optical properties | Biaxial (−) |
| Refractive index | nα = 1.660 nβ = 1.705 nγ = 1.713 |
| Birefringence | δ = 0.053 |
| 2V angle | 50° (measured) |
| Dispersion | Weak, strong |
| Ultraviolet fluorescence | Non-fluorescent |
| References | |
Tarbuttite is a rare phosphate mineral with formula Zn2(PO4)(OH). It was discovered in 1907 in what is now Zambia and named for Percy Coventry Tarbutt.