Cetineite

Formula: NaK5Sb14S6O18(H2O)6
Sulphide
Specific gravity: 4.21
Hardness: 3½
Streak: Orange
Colour: Orange-red
Solubility:
Environments: Slag locality
At the type locality, Le Cetine di Cotorniano Mine, Siena Province, Tuscany, Italy, cetineite formed in slag cavities in the dumps of the Cetine antimony deposit by weathering of rock and slag that were accumulated during mining operations at the beginning of the 20th century, in highly silicified evaporites, on ore which has been roasted, then long weathered, associated with mopungite and senarmontite.

Common impurities: S,Si