Gaudefroyite

General Information: Chemical Formula:Ca4Mn+++3-x(BO3)3(CO3)(O,OH)3 Composition:(Molecular Weight = 582.85 gm)Calcium 27.51 % CaManganese 23.56 % MnBoron 5.56 % B Hydrogen 0.13 % H Carbon 2.06 % C Oxygen 41.18 % O  Empirical Formula: Ca4Mn3+2.5(BO3)3(CO3)O2.25(OH)0.75 IMA Status:Approved IMA 1964Physical Properties: Cleavage:None Color:black. Density:3.35 - 3.5, Average = 3.42 Diaphaniety:Subopaque Hardness:6 - Orthoclase Luster:Adamantine - Resinous Streak:brownMore details...