Bismutite

Formula: Bi2O2(CO3)
Anhydrous carbonate
Specific gravity: 6.7 to 7.4
Hardness: 2½ to 3½
Streak: Grey
Colour: Yellow to brown, greenish, green-grey, grey or black; colourless or tinted in shades of faint yellow, green, etc. in transmitted light.
Solubility: Soluble in acids with effervescence
Environments:

Pegmatites
Hydrothermal environments

Bismutite is a relaatively common secondary bismuth carbonate, and an alteration product of bismuthinite and native bismuth. Associated minerals include bismuth, bismuthinite, tetradymite, arsenobismite, beyerite, bismite, cerussite, limonite, malachite, mixite, pucherite and sillénite.

Common impurities: Fe, Cu