Akrochordite

Formula: Mn₄Mg(AsO₄)₂(OH)₄^.4H₂O

Origin of name:  From Greek for wart, for the minerals typical habit

Crystal system:  Monoclinic

Crystal class:  2/m

Twinning:

Unit cell: a = 5.682 Å, b = 17.627 Å, c = 6.832 Å, b = 99.49°

Colour:  Reddish brown with yellow tint, light to dark brown, colourless, pale pink

Diaphaneity: Translucent

Luster: Dull

Habit:  Crystals minute, prismatic to lath-like,  in spherical or wart-like aggregates

Hardness:  3.5

Specific gravity:  3.26

Cleavage:  2; {010} perfect and second perpendicular to the first

Tenacity:

Streak:

Synonyms/varieties:

Comments: A rare mineral in hausmannite ore from a metamorphosed Fe-Mn orebody; in a metamorphosed stratiform zinc orebody.