Copper is one of the few metallic elements that occur in nature uncombined with other elements. Such copper, called native copper, occurs in lumps of various sizes. One of the most important ores of copper is chalcocite, a dark gray mineral containing copper sulfide. Chalcopyrite is a sulfide of copper and iron, having a yellowish appearance.
Malachite is a green basic carbonate of copper, sometimes polished and used in inlaid work. Azurite has a similar composition, but its color is bright to deep blue. Cuprite, red copper oxide, and melaconite and tenorite, black copper oxide, are copper ores of less importance.