Klyuchevskite

Formula:  K₃Cu₃FeO(SO₄)₄

Origin of name:  From locality; Klyuchevskaya volcanos, Russia

Crystal system:  Monoclinic

Crystal class:  2

Twinning: 

Unit cell: 

Colour:  Dark green to olive green

Diaphaneity:  Transparent

Luster:  Semimetallic

Habit:  Crystals acicular elongate to 0.1 mm in unoriented aggregates

Hardness:  3.5

Specific gravity:  3.1

Cleavage:  None

Tenacity: 

Streak:  Light green

Synonyms/varieties:

Comments:  Readily soluble in water and weak acid, hydrates in air in one week