Arsenoclasite

Formula:  Mn₅(AsO₄)₂(OH)₄

Origin of name:  From arsenic and Greek klas = to break

Crystal system:  Orthorhombic

Crystal class:  222

Twinning:

Unit cell: a = 18.29 Å, b = 5.75 Å, c = 9.31 Å

Colour:  Red, dark orange-brown

Diaphaneity: Translucent to transparent

Luster: Adamantine

Habit:  Massive, granular

Hardness:  5-6

Specific gravity:  4.16

Cleavage:  1; {010} perfect

Tenacity:

Streak:

Synonyms/varieties:

Comments: Found as a rare fissure mineral in a metamorphosed Fe-Mn orebody; in a sedimentary Fe-Mn deposit.