Cuprotungstite Locality: Gamsberg , Khomas Region , Namibia ( Locality at mindat.org ) Size: 5.2 x 3.4 x 3 cm. A very fine specimen of the rare (for this location) Cuprotungstite. These clusters are composed of olive green tabular microcrystals. This is the first time I have seen this species even mentioned from Gamsberg. Often, Cuprotungstite is found after Scheelite, but since there is no Scheelite, I wonder if these exceptional pockets are primary. Either way, a strange locality for Cuprotungstite. Ex. Charlie Key stock. — Photo: Robert M. Lavinsky · CC BY-SA 3.0
Cuprotungstite
Cuprotungstite is an IMA-recognized mineral species in the tungstate class, with the chemical formula Cu²⁺₃(WO₄)₂(OH)₂.
It crystallizes in the tetragonal crystal system (space group P4_12_12).
Key properties: specific gravity 5.4–6.98; Greenish gray to greenish yellow streak; Vitreous, waxy, earthy luster; optically uniaxial.
IMA symbol Ctgs, grandfathered status — known before the IMA’s founding, named in 1869.
A rare secondary mineral typically replacing scheelite.
It is found associated with Scheelite, stolzite, raspite.
The name refers to copper, cuprum and tungsten in the composition.