Bismutite or bismuthite is a bismuth carbonate mineral with formula Bi₂(CO₃)O₂ (bismuth subcarbonate). Bismutite occurs as an oxidation product of other bismuth minerals such as bismuthinite and native bismuth in hydrothermal veins and pegmatites. It crystallizes in the orthorhombic system and typically occurs as earthy to fibrous masses.

It was first described in 1841 for an occurrence in Saxony.

References

• Handbook of mineralogy