Cornwallite is an uncommon copper arsenate mineral with formula Cu5(AsO4)2(OH)4. It forms a series with the phosphate pseudomalachite and is a dimorph of the triclinic cornubite. It is a green monoclinic mineral which forms as radial to fibrous encrustations.
Discovery and occurrence
It was first described in 1846, for an occurrence in
Wheal Gorland, St Day United Mines of the
St Day,
Cornwall,
England.
[ It occurs as secondary mineral in the redox zone of copper sulfide deposits. Associated minerals include olivenite, cornubite, arthurite, clinoclase, chalcophyllite, strashimirite, lavendulan, tyrolite, spangolite, austinite, conichalcite, brochantite, azurite and malachite.][
]
See also
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Kernowite, another mineral named after Cornwall
