Hübnerite or hubnerite is a mineral consisting of manganese tungsten oxide (chemical formula MnWO4). It is the manganese endmember of the manganese–iron wolframite solid solution series.
It forms reddish brown to black monoclinic prismatic submetallic crystals. The crystals are typically flattened and occur with fine striations. It has a high specific gravity 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.
Hübnerite
Sample from the Pasto Bueno District, Pallasca Province, Ancash Department, Peru, showing deep red internal reflections when backlit (Size: 6.6 x 4.2 x 1.6 cm)
In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid substance with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.
Crystals of serandite, natrolite, analcime, and aegirine from Mont Saint-Hilaire, Quebec, Canada
Schist is a metamorphic rock characterized by an abundance of platy minerals. In this example, the rock has prominent sillimanite porphyroblasts as large as 3 cm (1.2 in).
Hübnerite, the manganese-rich end-member of the wolframite series, with minor quartz in the background
When minerals react, the products will sometimes assume the shape of the reagent; the product mineral is termed a pseudomorph of (or after) the reagent. Illustrated here is a pseudomorph of kaolinite after orthoclase. Here, the pseudomorph preserved the Carlsbad twinning common in orthoclase.
