Formula: CuO
Simple oxide
Specific gravity: 6.4
Hardness: 3½
Streak: Black
Colour: Grey-black

Volcanic sublimates
Hydrothermal environments

Tenorite is a secondary copper mineral present to some degree in virtually all oxidised copper deposits. It is also a volcanic sublimate.
In the oxidized zone chalcopyrite may be oxidized to yield Cu2+, and this may cause the precipitation of copper oxides such as tenorite:
Cu2+ + H2O → CuO (tenorite) + 2H+
Tenorite is associated with cuprite, copper, chrysocolla, malachite, azurite and cotunnite (volcanic sublimates) (HOM).

At the Girilambone mine, New South Wales, Australia, tenorite occurs in veins cutting chlorite schist, associated with malachite. Elsewhere at the mine cuprite enclosed by tenorite is associated with malachite and azurite in quartz-hematite gossan (AJM 11.2.98).

At Bisbee, Arizona, USA, tenorite is commonly associated with copper nodules (MinRec 43.1 supplement).

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