Bismutostibiconite

Formula: (Bi,Fe3+,☐)2Sb5+2O7
Antimonate
Specific gravity: 7.38
Hardness: 4 to 5
Colour: Yellow to yellow-brown, rarely greenish; brownish in transmitted light
Environments:

Hydrothermal environments

Bismutostibiconite is a secondary mineral forming earthy crusts on quartz, baryte and sandstone as an alteration product of bismuth-rich tetrahedrite-tennantite, associated with tetrahedrite-tennantite, chalcopyrite, beyerite, atelestite, preisingerite, bismutite, malachite, azurite and olivenite.