Magnussonite

General Information: Chemical Formula:Mn++5As+++3O9(OH,Cl) Composition:(Molecular Weight = 665.07 gm)Manganese 41.30 % MnArsenic 33.80 % AsHydrogen 0.11 % H Chlorine 1.33 % ClOxygen 23.46 % O  Empirical Formula: Mn2+5As3O9OH0.75Cl0.25Physical Properties: Color:blue green, grass green, or dark red. Density:4.3 Hardness:3.5-4 - Copper Penny-Flourite Luster:Vitreous (Glassy) Streak:whiteMore details...

Mn5(AsO3)3(OH,Cl)