Digenite

Formula:  Cu9S5

Origin of name:   From Greek for two sexes, in reference to the presumed presence of both cuprous and cupric ions

 

Crystal system:   Cubic

Crystal class:  -3 2/m

Twinning:

Unit cell: a = 5.57 Å

 

Colour:   Deep blue to black

Diaphaneity: Opaque

Luster:   Submetallic

Habit:   Crystals rare; massive

Hardness:   2.5 to 3

Specific gravity:   5.6

Cleavage:   None

Tenacity:   Conchoidal fracture; brittle

Streak: 

 

Synonyms/varieties:

 

Comments: Found in hydrothermal copper deposits of primary and secondary origin. Formed under a wide range of conditions, reported from mafic intrusives, as an exhalation product and in pegmatites.

 

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