Zwieselite

General Information: Chemical Formula:(Fe++,Mn)2(PO4)F Composition:(Molecular Weight = 225.21 gm)Manganese 12.20 % MnIron 37.20 % FePhosphorus 13.75 % P Oxygen 28.42 % O Fluorine 8.44 % F  Empirical Formula: Fe2+1.5Mn2+0.5(PO4)FPhysical Properties: Cleavage:[001] Good, [010] Distinct, [100] Indistinct Color:dark brown, black, or black brown. Density:3.927 - 3.97, Average = 3.94 Diaphaniety:Translucent Hardness:5-5.5 - Apatite-Knife Blade Luster:Vitreous - Resinous Streak:whiteMore details...