Arsenolamprite

Formula:  As

Origin of name:  From arsenic and Greek lampros = brilliant in allusion to its reflectance

Crystal system:  Orthorhombic

Crystal class:  2/m 2/m 2/m

Twinning:

Unit cell: a = 3.63 Å, b = 4.45 Å, c = 10.96 Å

Colour:  Dark grey to grey white

Diaphaneity: Opaque

Luster:  Brilliant metallic

Habit:  Plates and veinlets

Hardness:  2

Specific gravity:  5.3 to 5.5

Cleavage:  perfect in one direction

Tenacity:

Streak:  Black

Synonyms/varieties:

Comments:  Dimorphous with arsenic. Found as platelets and veins in carbonate rocks, in calcite veins