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.

[3] It crystallizes in the orthorhombic system and typically occurs as earthy to fibrous masses.

[2] The term bismuthite has been used in the past for bismuthinite.

[6] This article about a specific carbonate mineral is a stub.