Copper sulfide

Copper sulfides (British English spelling: copper sulphide) describe a family of chemical compounds and minerals with the formula Cu_xS_y. Both minerals and synthetic materials comprise these compounds. Some copper sulfides are economically important ores.

Prominent copper sulfide minerals include Cu₂S (chalcocite) and CuS (covellite). In the mining industry, the minerals bornite or chalcopyrite, which consist of mixed copper-iron sulfides, are often referred to as "copper sulfides". In chemistry, a "binary copper sulfide" is any binary chemical compound of the elements copper and sulfur. Whatever their source, copper sulfides vary widely in composition with 0.5 ≤ Cu/S ≤ 2, including numerous non-stoichiometric compounds.

The naturally occurring mineral binary compounds of copper and sulfur are listed below. Investigations of "blaubleibender covellite" (black) formed by natural leaching of covellite (CuS) indicate that there are other metastable Cu-S phases still to be fully characterised.

Copper sulfides can be classified into three groups:

Monosulfides, 1.6 ≤ Cu/S ≤ 2: their crystal structures consist of isolated sulfide anions that are closely related to either hcp or fcc lattices, without any direct S-S bonds. The copper ions are distributed in a complicated manner over interstitial sites with both trigonal as well as distorted tetrahedral coordination and are rather mobile. Therefore, this group of copper sulfides shows ionic conductivity at slightly elevated temperatures. In addition, the majority of its members are semiconductors.

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