The Mineral Cuprite

Cuprite, a small ore of copper, is an oxide mineral containing copper. Because of its typical red color it is known as ruby copper.

Chemical Formula

Derivation of Name
Cuprite was first described in 1845 and derives it name from the Latin cuprum due its copper content.

It is a secondary mineral that forms in oxidized zones of copper sulfide deposits. It is normally found along with native Copper, Chrysocolla, Azurite, Tenorite, Malachite and a range of iron oxide minerals.

Nearly all crystals of Cuprite are too small to deliver faceted gemstones. Yet, one exceptional deposit at Onganja, Southwest Africa, discovered in the 1970s, has delivered crystals that were large, having gem quality. Practically, every faceted stone weighing more than one carat is from this sole deposit, which has long been mined out. The number of faceted gems exceeding two carats is difficult to guess.

We find Cuprite in the Ural Mountains, Sardinia and Altai Mountains, as well as in additional remote provinces in Arizona, Bolivia, Chile, France, Cornwall and Namibia.

The crystals of the mineral Cuprite have its internal reflections red in color. They are of the hexoctahedral group and the systems are isometric. These crystals appear in the form of dodecahedral, cubic or octahedral form, and at times, in a combination of these forms. Often, double penetration takes place. The hardness number of this crystal is 3.5 – 4 Mohs. As such, despite its attractive colors, it is hardly used in jewelry. Its specific gravity is as high as 6.1, its cleavages are faulty, besides, they are brittle and form a conchoidal fracture. It has impregnable brilliant to a sub-metallic gleam. The “chalcotrichite" exhibits extensively lengthened (parallel to [001]) needle-like or capillary crystal formations.

Color varies from red to a deep red that could appear almost black.

6.14 g/cm3

Mohs scale hardness  
3.5 to 4

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