Cuprite: Gemstones Information
Though fine transparent red crystals of the red copper oxide (Cu2O) occurnaturally at the Onganja mine, Namibia, and have been faceted, synthetic cuprite has been grown and some faceted examples are magnificent. Both natural and synthetic cuprites are liable to undergo some surface alteration to malachite after long exposure to light. Cuprite crystals occur as cubes, octahedra or combinations of forms of the cubic system. The hardness is 3.5–4 and the SG 6.14. The RI is 2.84. Cuprite occurs in the oxidized zones of copper deposits.