Formula: BiO(OH) is the IMA formula, but the pure mineral is not known. BiO(OH,Cl) is a better formula. If OH > Cl the mineral is
daubréeite, otherwise it is bismoclite
Oxyhalide, matlockite group
Specific gravity: 6.4 to 6.5
Hardness: 2 to 2½
Colour: Creamy-white, greyish, yellowish-brown, colourless in transmitted light
Solubility: Totally soluble in acids. Re-precipitates upon substantial dilution (Mindat)
Daubréeite occurs only as massive material.
At the type locality, the Constancia mine, Cerro Tazna, Nor Chichas Province, Potosí, Bolivia, daubréeite occurs as a secondary mineral formed by alteration of bismuth or bismuthinite in the oxidation zone of a bismuth deposit, associated with clay minerals (Mindat, HOM).
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