Chalcocite, an opaque mineral having a metallic luster, is a significant copper ore mineral. The crystal arrangement of this sulfide is orthorhombic. It is among the most vital sources for obtaining copper.
Copper sulfide: Cu2S
Derivation of Name
The outdated name of the mineral Chalcocite is chalcosine, which has been derived from Greek word khalkos that means copper. Its other names are copper glance, vitreous copper and redruthite.
At times, chalcocite may be found as the main element in hydrothermal deposits. Nevertheless, most of it is found near the surface of enriched oxidized copper deposits formed as a consequence of copper that leaked from oxidized mineral. It is frequently located in sedimentary rocks.
This most viable copper ore has been mined for generations because it has a high content of copper, eighty percent by weight and an atomic ratio of 66.6 percent. Another reason that makes it the most significant copper ore is that copper can easily be separated from its sulfites.
It is seldom utilized as a gemstone.
The prominent places where Chalcocite occurs are Connecticut, Morenci, Bristol, Montana, Butte and other places like Bisbee, Bingham Canyon, Arizona, Utah, Tennessee, Ducktown, USA; England, Cornwall; Nambia, Tsumeb; Rio Tinto, Italy, Tuscany and Spain.
Being a secondary mineral, chalcocite is formed by the transformation of other minerals. It is known to form pseudo morphs of many different minerals. A pseudo morph is a mineral compound or mineral appearing in an unusual form that results from a process of substitution where the dimensions and appearance stay unchanged, but where another mineral replaces the original mineral. Chalcocite has been identified for forming pseudo morphs of minerals like Bornite, Chalcopyrite, Covellite, Enargite, Galena Mille Rite, Galena Pyrite and Sphalerite. For collectors, this is a preferred and iconic mineral. Good crystals of this mineral obtained from old and exhausted mines from Bristol, Connecticut and Conwell fetch a very high price.
Its color varies from dark gray to black.
Mohs scale hardness
2½ - 3