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Formula: Cu3(PO4)(OH)3
Anhydrous phosphate containing hydroxyl
Crystal System: Orthorhombic
Specific gravity: 4.10 measured, 4.14 calculated
Hardness: 4½
Colour: Dark blue to green-blue; green-blue in transmitted light.
Solubility: Soluble in cold hydrochloric acid
Common impurities: Fe,Mg,Al,Si,As,Co
Environments:
Cornetite is a secondary mineral in the oxidised zone of
some hydrothermal copper deposits,
(Webmin, HOM)
associated with copper, brochantite,
pseudomalachite, libethenite,
malachite, atacamite,
chrysocolla and heterogenite
(HOM).
At the Desolation Prospect, Queensland, Australia, cornetite is very rare, but has been found associated with
pseudomalachite and chrysocolla
(AJM 17.2.85).
At the type locality, L'Etoile du Congo mine, Democratic Republic of the Congo, cornetite occurs in fine-grained
argillaceous sandstone associated with
pseudomalachite
(Dana).
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