Mineral description : Chalcocite

Mineral class	Sulphides : Chalcocite group
Chemical formula	Cu2S
Crystal system	Monoclinic (pseudo-orthorombic).
Habitus	Flat pseudohexagonal crystals. Usually massive grainy aggregates.
Cleavage	Imperfect in two prismatic directions.
Hardness	2.5 - 3
Density	5.5 - 5.8
Color	Grayish black, opaque.
Streak	Shiny black to dark gray.
Luster	Metallic.
Description	Chalcosite is an important copper ore.
Occurance	Forms in hydrothermal veins and below the oxidation zone of copper deposits. Also found in sedimentary rocks.
Associates
Notes	Often found with a dull tarnish. Easily soluble in nitric acid. Green color in a flame.
Localities	Found only in a few of the copper ores in Sweden Grindsbol, Dalsland. In quartz veins. Glava, Dalsland. In quartz veins. Sjangeli, Lappland. Nautanen, Lappland. Fridhem, Lappland. Solstads copper mine, Småland. Norberg, Västmanland. Fröå, Jämtland.

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