Category Sulfide minerals
Chemical formula copper(I) sulfide: Cu2S
Strunz classification 02.BA.05a
Crystal symmetry Monoclinic 2/m - Prismatic
Unit cell a = 15.246(4) Å, b = 11.884(2) Å, c = 13.494(3) Å; β = 116.35(1)°; Z = 96
Color Dark gray to black
Crystal habit Tabular to prismatic crystals also massive to granular
Crystal system Monoclinic, pseudo-orthorhombic
Twinning Common on {110} yielding pseudohexagonal stellate forms
Cleavage Indistinct on {110}
Fracture Conchoidal
Tenacity Brittle to sectile
Mohs scale hardness 2.5 - 3
Luster Metallic
Streak Shiny black to lead gray
Diaphaneity Opaque
Specific gravity 5.5 - 5.8
Fusibility 2-2.5
References [1][2][3]

Chalcocite, copper(I) sulfide (Cu2S), is an important copper ore mineral. It is opaque, being colored dark-gray to black with a metallic luster. It has a hardness of 2½ - 3. It is a sulfide with an orthorhombic crystal system.

The term chalcocite comes from the alteration of the obsolete name chalcosine, from the Greek khalkos, meaning copper. It is also known as redruthite, vitreous copper and copper-glance.


Chalcocite is sometimes found as a primary vein mineral in hydrothermal veins. However, most chalcocite occurs in the supergene enriched environment below the oxidation zone of copper deposits as a result of the leaching of copper from the oxidized minerals. It is also often found in sedimentary rocks.

It has been mined for centuries and is one of the most profitable copper ores. The reasons for this is its high copper content (67% atomic ratio and nearly 80% by weight) and the ease at which copper can be separated from sulfur.

Chalcocite crystals from the Mammoth Mine, Mount Isa - Cloncurry area, Queensland, Australia (size: 3.0 x 2.9 x 2.4 cm)

Since chalcocite is a secondary mineral that forms from the alteration of other minerals, it has been known to form pseudomorphs of many different minerals. A pseudomorph is a mineral that has replaced another mineral atom by atom, but it leaves the original mineral's crystal shape intact. Chalcocite has been known to form pseudomorphs of the minerals bornite, covellite, chalcopyrite, pyrite, enargite, millerite, galena and sphalerite.

See also


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Look at other dictionaries:

  • Chalcocite — Catégorie II : sulfures et sulfosels[1] Chalcocite St Agnes, Cornouailles Angleterre (9x7cm) …   Wikipédia en Français

  • Chalcocite — Chal co*cite, n. [Gr. chalko s brass.] (Min.) Native copper sulphide, called also {copper glance}, and {vitreous copper}; a mineral of a black color and metallic luster. [Formerly written {chalcosine}.] [1913 Webster] …   The Collaborative International Dictionary of English

  • chalcocite — [kal′kə sīt΄] n. [see CHALCO ] a dark gray, lustrous mineral, Cu2S, that is an ore of copper; cuprous sulfide …   English World dictionary

  • chalcocite — /kal keuh suyt /, n. a common mineral, cuprous sulfide, Cu2S: an important ore of copper. [1865 70; irreg. CHALCO + (ANTHRA)CITE] * * * Sulfide mineral, Cu2S, that may be an important ore of copper. It belongs to a group of sulfide minerals… …   Universalium

  • chalcocite — noun Etymology: alteration of chalcosine, from French, irregular from Greek chalkos Date: 1868 a black or gray lustrous metallic mineral that consists of a sulfide of copper and is an important copper ore …   New Collegiate Dictionary

  • chalcocite — noun Cuprous sulphide, CuS, an important ore of copper …   Wiktionary

  • chalcocite — Смотри Халькозин …   Энциклопедический словарь по металлургии

  • chalcocite — chal·co·cite …   English syllables

  • chalcocite — chal•co•cite [[t]ˈkæl kəˌsaɪt[/t]] n. mir a common mineral, cuprous sulfide, Cu2S: an important ore of copper • Etymology: 1865–70; chalco + (anthra) cite …   From formal English to slang

  • chalcocite — /ˈkælkəsaɪt/ (say kalkuhsuyt) noun a common mineral, cuprous sulphide, Cu2S, an important ore of copper …  

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