| Tungstite | |
| Formula: | WO3·H2O |
| Imasymbol: | Tgs[1] |
| Molweight: | 249.86 g/mol |
| Strunz: | 4.FJ.10 |
| System: | Orthorhombic |
| Class: | Dipyramidal (mmm) H-M symbol: (2/m 2/m 2/m) |
| Symmetry: | Pmnb |
| Color: | Yellow, yellowish green/orange |
| Habit: | Earthy, pulverulent |
| Cleavage: | Perfect along [001], imperfect along [110] |
| Mohs: | 2.5 |
| Luster: | Resinous, pearly |
| Refractive: | nα = 2.090, nβ = 2.240, nγ = 2.260 |
| Opticalprop: | Biaxial (-) |
| Birefringence: | δ = 0.170 |
| Dispersion: | r < v (strong) |
| Streak: | Yellow |
| Gravity: | 5.517 |
| Diaphaneity: | Transparent |
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.