Arsentsumebite

Formula:  Pb₂Cu(AsO₄)(SO₄)(OH)

Origin of name:  From arsenic and tsumebite

Crystal system:  Monoclinic

Crystal class:  2/m

Twinning: Complex

Unit cell: a = 8.85 Å, b = 5.92 Å, c = 7.84 Å, b = 112.6°

Colour:  Green, grass-green to apple-green

Diaphaneity: Semi-transparent

Luster: Vitreous

Habit:  Crusts of distorted crystals

Hardness: 3.5 ?

Specific gravity:  6.46

Cleavage: None

Tenacity: Brittle

Streak: Light green

Synonyms/varieties:

Comments: Member of the brackebuschite group. A rare mineral in the oxidised zone of a dolostone-hosted hydrothermal poly-metallic ore deposit; in a hydrothermal polymetallic barite-fluorite deposit.