Cuprite is a secondary mineral, forming in the oxidized zones of Copper deposits. It is often referred to as ruby copper as a result of its unique deep-red color. Its name is derived from the Latin word for copper; cuprum. It can also be brown-red, purplish-red, and even appear to be black. Its luster is typically adamantine (“diamond like”) to sub-metallic (when nearly opaque). Due to its softness (3.5-4 on the Mohs hardness scale) and the rarity of gem-quality crystals, it does not have a major presence in the gem/jewelry trade. It often occurs in association with Native Copper, Malachite, Azurite, Calcite and Chalcocite. A fibrous form is known as Chalcotrichite.
The crystal system for Cuprite is isometric, typically forming octahedral crystals or groups of octahedral crystals, and less frequently as cubic or dodecahedral forms. Other forms includes penetration twins, encrusting, capillary, fibrous, radiating and massive.
Quality specimens of Cuprite are found in various locations, including China, DR Congo, England, France, Kazakhstan, Namibia, Russia and the USA (Arizona).