Formula: Cu2O
Oxide
Specific gravity: 6.15
Hardness: 3½ to 4
Streak: Brownish red
Colour: Red
Solubility: Moderately soluble in hydrochloric acid; slightly soluble in sulphuric and nitric acid
Environments:
Cuprite is a secondary mineral found in the oxidation
portions of high temperature copper deposits, associated with
limonite and secondary
copper minerals such as
native copper,
malachite,
azurite and
chrysocolla.
It may be found as an oxidation product coating native copper, or as an alteration
product of
chalcopyrite.
At the Mashamba West Mine, Democratic Republic of Congo, cuprite is pseudomorphed by
shattuckite
(R&M 87.4.304-336).
At Tsumeb, Namibia, cuprite occurs in dolomite ore, and pseudomorphs of
malachite after cuprite have been recorded
(R&M 93.6.542).
At the Bardon Hill quarry, Coalville, Leicestershire, England, UK, cuprite occurs with native copper
altering to chrysocolla and malachite
(RES p193).
At New Cliffe Hill quarry, Stanton under Bardon, Leicestershire, England, UK, cuprite occurs with
native copper and malachite
(RES p197).
At the Cotopaxi Mine, Colorado, USA, cuprite crystals are found rimmed with green
malachite.
(R&M 84.6.547).
At the Chino mine, New Mexico, USA, cuprite occurs overgrown with
goethite.
(R&M 84.6.492-500).
Alteration
chalcocite, oxygen and water to cuprite and sulphuric acid
If acidic copper sulphate solutions pass through the oxidation zone to below the water table, conditions usually change
to reducing and the dissolved copper ions react with sulphide ions to form copper sulphides such as
chalcocite. If the water table falls, allowing the
chalcocite to be exposed to the oxidation zone, then cuprite may be
formed according to the above equation
(JRS 18.14).
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