Bismutite

a mineral of the oxycarbonate bismuth group. Its chemical composition is Bi₂(CO₃)O₂. It crystallizes in a tetragonal arrangement. Bismutite forms powdery masses or, less often, fibrous crusts consisting of submicroscopic crystalline particles. Bismutite’s hardness on the mineralogical scale measures 3–3.75; its density varies between 7,400 and 8,300 kg/m³. Its color ranges from grayish white or greenish yellow to brown and grey. It forms as a result of the oxidation of native bismuth, as well as bismuthinite, during the action of surface carbonated solutions. Quartz, topaz, and arsenopyrite, among others are bismutite’s associated minerals. Deposits of bismutite are found in Transbaikalia, Kazakhstan, and Middle Asia. Abroad they are found in Czechoslovakia, the German Democratic Republic, Mexico, the USA, and other countries.