Black crystals of the rare mineral bismutocolumbite in a contrasting matrix. From: Malkhan, Krasnyi Chikoy, Zabaykalsky Krai, Russian Federation. — Photo: David Hospital · CC BY-SA 4.0
Bismutocolumbite
Bismutocolumbite is an IMA-recognized mineral species in the oxides & hydroxide class, with the chemical formula BiNbO₄.
It crystallizes in the orthorhombic crystal system (space group Pnna).
Key properties: Mohs hardness 5.5; specific gravity 7.56; Brown to pale yellow streak; Submetallic luster; optically biaxial.
IMA symbol Bclb, IMA status: approved, named in 1991.
Found in a pegmatite.
It is found associated with Elbaite, bismuth-rich microlite, cassiterite, danburite, quartz.
The name refers to BISMuth in its composition and relation to minerals of the columbite–tantalite series.