Bismite is a bismuth oxide mineral, bismuth trioxide or Bi2O3. The mineral was named after the presence of bismuth in its composition. It is a monoclinic mineral, but the typical form of occurrence is massive and clay-like with no macroscopic crystals. The color varies from green to yellow. It has a Mohs hardness of 4 to 5 and a specific gravity of 8.5 to 9.5, quite high for a nonmetallic mineral.
Bismite is a secondary oxidation zone mineral which forms from primary bismuth minerals. It was first described from Goldfield, Nevada in 1868, and later from the Schneeberg District, Ore Mountains, Saxony, Germany.
- Category: Oxide minerals
- Formula: Bi2O3
- Crystal system: Monoclinic
- Crystal class: Prismatic (2/m) (same H-M symbol).
Bismite is a yellow, gray-green, or green-yellow mineral, having transparent to translucent appearance, light yellow streak, and adamantine luster. It can be formed as earthy, scaly, or pulverulent structures.
The average density of the mineral is 9 g/cm3, and its hardness ranges from 4 to 5.
- Lustre: Sub-Adamantine, Dull, Earthy
- Transparency: Opaque
- Colour: Greyish green, greenish yellow to bright yellow
- Streak: Grey to yellow
- Hardness: 4½ on Mohs scale
- Fracture: Uneven – Flat surfaces (not cleavage) fractured in an uneven pattern.
- Density: 8.64 – 9.22 g/cm3 (Measured) and 10.4 g/cm3 (Calculated)
Bismite occurs as an oxidation product of bismuth. It is an oxidation product of bismuth. It is closely associated with cassiterite, bismutite, and bismuth.