Aktashite

Formula: Cu₆Hg₃As₄S₁₂

Origin of name:  Locality; Aktash mercury deposit, Russia

Crystal system:  Hexagonal, pseudo-cubic

Crystal class:  3

Twinning:

Unit cell: a = 13.72 Å, c = 9.32 Å

Colour:  Grayish black, sometimes with bluish tint

Diaphaneity: Opaque

Luster:  Metallic

Habit:  Crystals resemble trigonal pyramids; xenomorphic grains

Hardness:  3.4 to 4

Specific gravity:  5.50

Cleavage: None

Tenacity: brittle

Streak:  Black

Synonyms/varieties:

Comments:  Series with gruzdevite. Of hydrothermal origin.