Tungstite
| Tungstite | |
|---|---|
Bright yellow tungstite on ferberite | |
| General | |
| Category | Minerals |
| Formula | WO3·H2O |
| IMA symbol | Tgs |
| Strunz classification | 4.FJ.10 |
| Crystal system | Orthorhombic |
| Crystal class | Dipyramidal (mmm) H-M symbol: (2/m 2/m 2/m) |
| Space group | Pmnb |
| Identification | |
| Formula mass | 249.86 g/mol |
| Color | Yellow, yellowish green/orange |
| Crystal habit | Earthy, pulverulent |
| Cleavage | Perfect along [001], imperfect along [110] |
| Mohs scale hardness | 2.5 |
| Luster | Resinous, pearly |
| Streak | Yellow |
| Diaphaneity | Transparent |
| Specific gravity | 5.517 |
| Optical properties | Biaxial (-) |
| Refractive index | nα = 2.090, nβ = 2.240, nγ = 2.260 |
| Birefringence | δ = 0.170 |
| Dispersion | r < v (strong) |
Tungstite is a hydrous tungsten oxide mineral with formula: WO3·H2O. It is a secondary mineral formed by the weathering of other tungsten containing minerals. It crystallizes in the orthorhombic system in translucent yellow to yellow green masses. It is clay-like with Mohs hardness of 2.5 and a specific gravity of 5.5.
It was first described in 1868 for an occurrence near Trumbull, Connecticut at the Hubbard Tungsten Mine at Long Hill.