Cobaltomenite Locality: El Dragón mine, Antonio Quijarro Province , Potosí Department , Bolivia ( Locality at mindat.org ) Picture width 1 mm. Collection and photograph Christian Rewitzer — Photo: Christian Rewitzer · CC BY-SA 3.0
Cobaltomenite
Cobaltomenite is an IMA-recognized mineral species in the oxides & hydroxide class, with the chemical formula Co(Se⁴⁺O₃)·2H₂O.
It crystallizes in the monoclinic crystal system (space group P2_1/n). It is a member of the Cobaltomenite structural group.
Key properties: Mohs hardness 2.5; specific gravity 3.42; Vitreous luster; optically biaxial.
IMA symbol Cbm, IMA status: approved, named in 1882.
Found as a secondary mineral in the oxidation zone of hydrothermal selenium-sulfide- bearing vein deposits.
It is found associated with Chalcomenite, molybdomenite (Cerro de Cacheuta, Argentina); chalcomenite, clinochalcomenite, lepidocrocite, gypsum (El Dragón mine, Bolivia).
The name refers to the content of cobalt and the Greek for moon.