Bismite - Encyclopedia

    Class : Oxides and hydroxides
    Subclass : Oxides
    Crystal System : Monoclinic
    Chemistry : Bi2O3
    Rarity : Rare

Bismite is a rare bismuth oxide. It is a mineral of high density (more than 8) which results from the oxidation of bismuth minerals in the superficial zone of high temperature veins. Its name derives from its chemical composition : bismuth. In collection samples, confusion with bismutite, bismuth carbonate, seems frequent. It forms earthy to powdery masses, sometimes compact, yellow to grey-yellow, white and greyish-green ; the crystals are microscopic.

Main photo : Bismite from Cogola Alta Mine, Andalusia, Spain © Christian Rewitzer

Bismite in the World

The finest specimens of bismite come from the pegmatites of Ampangabé and Fefena (Madagasar), but bismite is especially common in the tin, lead, silver and bismuth veins of Oruro, Lallagua, Colavi (Bolivia). It is known in the polymetallic argentiferous vein of Schneeberg (Saxony, Germany) and in the Californian pegmatites of Pala and Rincon.

Bindheimite in France

In France, bismite is known in the oxidized zone of the bismuth vein of Meymac (Corrèze), but also in Montmins (Allier), Brézouard (Haut-Rhin) and La Fumade (Tarn).

Twinning and special crystallizations

No twins known for this mineral species.

Fakes and treatments

No fake or treatment recorded for this mineral species.

Hardness : 4.5
Density : 8.6 to 9.2
Fracture : Irregular
Trace : Gray to yellow

TP : Opaque
RI : 2.42
Birefringence : 0
Optical character : Biaxial
Pleochroism : None
Fluorescence : None

Solubility : -

Magnetism : None
Radioactivity : None