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Mineralpedia Details for Cornwallite

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Cornwallite

Cornwallite

The type locality of the mineral is its namesake, at Wheal Gorland of the St. Day United Mines in Cornwall, England. Cornwallite is an uncommon mineral that occurs in oxidized copper deposits in localities in, additionally, France, Germany, Slovakia, Morocco, Tunisia, the United States, Mexico, Australia, and a number of other localities. Associated minerals include olivenite, cornubite, arthurite, clinoclase, chalcophyllite, strashimirite, lavendulan, tyrolite, spangolite, austenite, conichalcite, brochantite, azurite, and malachite.

Ref. Handbook of Mineralogy, Anthony et al (1995) and MSA at http://www.handbookofmineralogy.org/pdfs/cornwallite.pdf

Formula
Cu5(AsO4)2(OH)4 
Crystal System
Monoclinic 
Crystal Habit
Massive, Radial, Encrustations 
Cleavage
None, None, None 
Luster
Earthy (Dull) 
Color
light green, dark green, black green 
Streak
apple green 
Class
Monoclinic - Prismatic 
Fracture
Conchoidal 
Hardness
4-5 
WebMineral
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Mindat
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Cornwallite from San Rafael mine, Nye Co., Nevada, United States

Cornwallite
            from San Rafael mine, Nye Co., Nevada, United States

Tiny green beads of Cornwallite to about 0.5mm with olive green Olivenite crystals to 2mm.

Click thumbnail images for larger view.

Cornwallite from Majuba Hill mine, Pershing Co., Nevada, United States

Cornwallite
            from Majuba Hill mine, Pershing Co., Nevada, United States

Bright green layer of botryoidal Cornwallite.

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Cornwallite from Cap Garonne mine, Le Pradet, Var, France

Cornwallite
            from Cap Garonne mine, Le Pradet, Var, France

Tiny green beads of Cornwallite with acicular Olivenite.

Click thumbnail images for larger view.

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