Bright yellow massive tungstite on ferberite from Calacalani , Bolivia . Photograph taken at the Natural History Museum , London . — Photo: Aram Dulyan ( User:Aramgutang ) · Public domain
Tungstite
Hydrated tungsten oxide — a yellow 'tungsten ocher' coating formed by weathering of tungsten ores.
Intro adapted from Wikipedia (CC BY-SA).
Tungstite is an IMA-recognized mineral species in the tungstate class, with the chemical formula WO₃·H₂O.
It crystallizes in the orthorhombic crystal system (space group Pmnb).
Key properties: Mohs hardness 2.5; specific gravity 5.517; Resinous, pearly on cleavages luster; refractive index 2.197; optically biaxial.
IMA symbol Tgs, grandfathered status — known before the IMA’s founding, named in 1868.
An alteration product of tungsten minerals, especially wolframite and ferberite, in hydrothermal tungsten-bearing deposits.
It is found associated with Hydrotungstite, ferritungstite, wolframite, ferberite, scheelite.
The name refers to TUNGSTen in the composition.