Hübnerite

Hübnerite or hubnerite is a mineral consisting of manganese oxide (chemical formula MnWO4). It is the manganese endmember of the manganese–iron wolframite series. It forms reddish brown to black monoclinic submetallic crystals. The crystals are typically flattened and occur with fine striations of 7.15 and a Mohs hardness of 4.5. It is transparent to translucent with perfect cleavage. Refractive index values are nα = 2.170 - 2.200, nβ = 2.220, and nγ = 2.300 - 2.320.

Typical occurrence is in association with high-temperature hydrothermal with greisen and in alluvial, arsenopyrite , tourmaline and fluorite

It was first described in 1865 for an occurrence in the Erie and Enterprise veins, Mammoth district, Nye County, Nevada , and named after the German mining engineer and metallurgist from Freiberg