Bismutite or bismuthite is a bismuth

Bismuth

Bismuth is a chemical element with symbol Bi and atomic number 83. Bismuth, a trivalent poor metal, chemically resembles arsenic and antimony. Elemental bismuth may occur naturally uncombined, although its sulfide and oxide form important commercial ores. The free element is 86% as dense as lead...

 carbonate mineral with formula Bi₂(CO₃)O₂ (bismuth subcarbonate

Bismuth subcarbonate

Bismuth subcarbonate Bi2O2, sometimes written 2CO3 is a chemical compound of bismuth containing both oxide and carbonate anions. Bismuth is in the +3 oxidation state. Bismuth subcarbonate occurs naturally as the mineral bismutite. Its structure consists of Bi-O layers and CO3 layers and is related...

). Bismutite occurs as an oxidation product of other bismuth minerals such as bismuthinite

Bismuthinite

Bismuthinite is a mineral consisting of bismuth sulfide . It is an important ore for bismuth. The crystals are steel-grey to off-white with a metallic luster...

 and native bismuth in hydrothermal veins

Vein (geology)

In geology, a vein is a distinct sheetlike body of crystallized minerals within a rock. Veins form when mineral constituents carried by an aqueous solution within the rock mass are deposited through precipitation...

 and pegmatite

Pegmatite

A pegmatite is a very crystalline, intrusive igneous rock composed of interlocking crystals usually larger than 2.5 cm in size; such rocks are referred to as pegmatitic....

s. 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

Saxony

The Free State of Saxony is a landlocked state of Germany, contingent with Brandenburg, Saxony Anhalt, Thuringia, Bavaria, the Czech Republic and Poland. It is the tenth-largest German state in area, with of Germany's sixteen states....

.