chalcocite

chal·co·cite

C0228300 (kăl′kə-sīt′)n. A dark gray mineral, essentially Cu₂S, that is an important ore of copper.

[Alteration of obsolete chalcosine, from Greek khalkos, copper.]

chalcocite

(ˈkælkəˌsaɪt) n (Minerals) a lead-grey or black mineral, found as a copper ore or in veins. It is a source of copper. Composition: copper sulphide. Formula: Cu2S. Crystal structure: orthorhombic[C19: changed from earlier chalcosine, from Greek khalkos copper + -ite¹]

chal•co•cite

(ˈkæl kəˌsaɪt)

n. a common mineral, cuprous sulfide, Cu₂S: an important ore of copper. [1865–70; chalco- + (anthra) cite]

Thesaurus

Noun

chalcocite - a heavy grey mineral that is an ore of coppercopper glanceatomic number 29, copper, Cu - a ductile malleable reddish-brown corrosion-resistant diamagnetic metallic element; occurs in various minerals but is the only metal that occurs abundantly in large masses; used as an electrical and thermal conductormineral - solid homogeneous inorganic substances occurring in nature having a definite chemical composition

Chalcocite

enUK

chalcocite

[′kal·kə‚sīt] (mineralogy) Cu₂S A fine-grained, massive mineral with a metallic luster which tarnishes to dull black on exposure; crystallizes in the orthorhombic system, the crystals being rare and small usually with hexagonal outline as a result of twinning; hardness is 2.5-3 on Mohs scale, and specific gravity is 5.5-5.8. Also known as beta chalcocite; chalcosine; copper glance; redruthite; vitreous copper.

Chalcocite

(also copper glance), a sulfide mineral, Cu₂S. Chalcocite usually contains admixtures of Ag; sometimes it contains Fe, Co, Ni, and As. A considerable copper deficit is occasionally observed in its composition.

Three polymorphic modifications of chalcocite are known. The most common is the orthorhombic modification, which at a temperature of 103°C alters to the hexagonal modification. Above 425°C, hexagonal chalcocite alters to the isometric modification. The structure of orthorhombic and hexagonal chalcocite is based on an extremely dense hexagonal packing of the sulfur atoms. The copper atoms occupy triangular vacancies in the plane of the densely packed “sulfur” layers.

Chalcocite is found in the form of fine-grained aggregates or phenocrysts in ores and rock. Crystals are rare, but hexagonal twins are common. Chalcocite is lead gray in color and has a metallic luster. An opaque and brittle mineral, it has a hardness of 2.5–3 on Mohs’ scale and a density of 5,780 kg/m³. It is a good conductor of electricity and an ore of copper.

The most valuable commercial accumulations of chalcocite are associated with the zones of oxidation of copper deposits, where chalcocite is found in association with bornite, chalcopyrite, and other sulfides (deposits at Bisbee, Ariz., and Butte, Mont., in the United States, at Braden and Chuquicamata in Chile, at Tsumeb in southwestern Africa, and at Dzhezkazgan in the USSR). Commercial concentrations of chalcocite occur in copper sandstones and shales. When it oxidizes at the earth’s surface, chalcocite forms cuprite, malachite, azurite, native copper, and other copper minerals.

REFERENCES

Mineraly: Spravochnik, vol. 1. Moscow, 1960.
Ramdohr, P. Rudnye mineraly i ikh srastaniia. Moscow, 1962. (Translated from German.)
Yund, R. A., and G. Kullerud. “Thermal Stability of Assemblages in the Cu—Fe—S System.” Journal of Petrology, 1966, vol. 7, no. 3.

IU. K. VOROB’EV

chalcocite

chal·co·cite

chalcocite

chal•co•cite

Chalcocite

chalcocite

Chalcocite

REFERENCES

chalcocite

Synonyms for chalcocite

noun a heavy grey mineral that is an ore of copper

Synonyms

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