Arseniopleite

Formula: NaCaMn²⁺(Mn²⁺, Mg)₂(AsO₄)₃

Origin of name: From arsenic and Greek for more, as it added to the number of related minerals previously described

Crystal system: Monoclinic

Crystal class: 2/m

Twinning:

Unit cell: a = 11.31 Å, b = 13.06 Å, c = 6.86 Å, b = 99°

Colour: Brownish red to cherry red, yellow, dark-green, gray

Diaphaneity: Opaque to translucent

Luster: Dull, greasy

Habit: commonly granular, massive, rarely as elongated or lenticular crude crystals

Hardness: 3-4

Specific gravity: 4.2

Cleavage: 1; pseudo-{10-11}

Tenacity:

Streak: Yellowish brown

Synonyms/varieties:

Comments: Member of the alluaudite group. Mn-member of series with caryinite. Found as fracture fillings and thin veins in banded dolostone; in a metamorphosed Fe-Mn ore body.