Sailaufite

Formula: Ca₂Mn₃(AsO₄)₂O₂CO₃·3H₂O

Origin of name: Named for the locality, Hartkoppe hill, Ober-Sailauf (Spessart mountains) Germany.

Crystal system: Monoclinic

Crystal class: m

Twinning: 

Unit cell: a = 11.253, b = 19.628, c = 8.932, β = 100.05°

Colour: Dark reddish brown to black

Diaphaneity: Translucent

Luster: Vitreous

Habit: Mammillary, tabular

Hardness: 4

Specific gravity: 

Cleavage: Distinct/good

Tenacity: Brittle, subconchoidal fracture

Streak: Brown

Synonyms/varieties:

Comments:  Arseniosiderite Group