Covellite

covellite [kō′ve‚līt]

(mineralogy)

CuS An indigo-blue mineral of metallic luster that crystallizes in the hexagonal system; it is usually massive or occurs in disseminations through other copper minerals and represents an ore of copper. Also known as indigo copper.

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Covellite 

(named for its discoverer, the Italian chemist N. Covelli, 1790–1829), a mineral of the sulfide class. Chemical composition, CuS; it contains 66.48 percent Cu and 33.52 percent S. The structure of covellite has Cu⁺ and Cu²⁺ atoms, as well as the simple ion S^2– and the paired ion S^22–. The structural elements of Cu²⁺ surrounded by three S^2– and Cu+ ions, which are in the centers of paired tetrahedrons connected by S₂² ions, are located in layers and provide the perfect cleavage of covellite. Thus, the structurally regular formula for covellite will be (Cu₂S#x00B7;CuS₂). Crystals are very rare; secondary incrustations, as well as films on other sulfides or powdery masses that replace them, are common. The color is dark blue. Hardness on the mineralogical scale, 1.5–2.0; density, 4,590–4,670 kg/m³. Covellite is a typical mineral in the zone of secondary sulfide enrichment in the oxidized parts of sulfide copper deposits. It is used as a copper ore.