Crystal system:                 Isometric                                             Hardness:                        3,5 - 4,0
Density:                               6,15 average                                      Streak:                             Red       
Colour:                                Red to a deep red that can appear almost black.
Cleavage:                            Is fair in four directions forming octahedrons.
Occurrence:                       Oxidized zone of copper deposits.
Habitat:                                Isometric (cubic), octahedral, and dodecahedral, as hair-like capillary forms, earthy, compact, granular and massive.
Composition:                     Oxide mineral    Cu2O

Cuprite was first described in 1845 and the name is derived from the Latin word cuprum meaning copper. It contains almost 88% copper.

Cuprite has been a major ore of copper and is still mined in many places around the world. Of all the copper ores, except for native copper, cuprite gives the greatest yield of copper per molecule since there is only one oxygen atom to every two copper atoms. Notable occurrences include Arizona, USA, Africa, Australia, Chile and several localities in Europe.

Associated minerals are copper, chrysocolla, malachite and azurite. A surface film forms after long exposure to strong light. Crystals of cuprite are sometimes altered or partially altered to malachite and rarely copper. Penetration twins frequently occur.

Cuprite is not very common in South Africa and where present, it is usually found with native copper. Small bright red crystals were found (rarely) in the Messina mines and small, shiny, red cubes and hair-like chalcotrichite has been found in oxidized ore at the Stavoren mine. Massive cuprite was found in some pegmatites in the Northern Cape, notably the Noumas pegmatite. There is an unusual occurrence of small amounts in sandstone at Clocolan in the Free State.

A cuprite specimen is probably the earliest collected specimen (1860) from Tsumeb. Cuprite was found in nearly all parts of the deposit. The most common occurrence was massive ore and crystals up to half a centimeter. Those specimens, often associated with malachite, mimetite and native copper were found abundantly at the mine during the seventies. Really large crystals up to 3 cm are rare. The finest specimens were found in 1992, in the third oxidation zone between 43 and 44 levels, when massive cuprite covered with green conichalcite was mined. In 1994 the largest crystals of cuprite from Tsumeb were collected on the 44th level, measuring 5 cm, and displaying primarily octahedral faces.

A hair-like variety of cuprite named “copper-blossom” by the German miners was discovered between 300 m and 390 m in the first oxidation zone. This chalcotrichite created attractive specimens with contrasting colour combinations of the red needles, the white calcite, and gemmy crystals of cerussite. Specimens of this kind have never been found again.

Tsumeb cuprite is among the finest in the world. Although it shares the glamour with the great occurrence at Zaire where larger crystals have been found, the latter are without the attractive, different associations of those from Tsumeb.

However, the largest crystals of cuprite in the world, up to 14 cm in diameter and 2,1 kg in weight, came from the Onganja copper mine in Namibia. These crystals were typically coated with a thin layer of malachite and were discovered in 1973. Crystals measuring 6-8 cm, not as large as the record-size specimens, but nevertheless enormous for the species, were not uncommon. Virtually every faceted cuprite gemstone over one carat in weight is from this single deposit.

The number of faceted gems over two carats is difficult to estimate, but according to Joel Arem, one-time curator of the Smithsonian National Gem and Mineral Collection in Washington DC, faceted cuprite of any size is considered one of the most collectable and spectacular gems in existence, with its deep garnet colouring and higher dispersion than a diamond. Only the gem’s soft nature prevents it from being among the most valuable jewellery stones.     JDJ