Magnesiohornblende

General Information: Chemical Formula:Ca2[Mg4(Al,Fe+++)]Si7AlO22(OH)2 Composition:(Molecular Weight = 821.16 gm)Calcium 9.76 % CaMagnesium 11.84 % MgAluminum 5.75 % AlIron 1.70 % FeSilicon 23.94 % SiHydrogen 0.25 % H Oxygen 46.76 % O  Empirical Formula: Ca2Mg4Al0.75Fe3+0.25(Si7AlO22)(OH)2 IMA Status:Approved IMA 1978Physical Properties: Cleavage:[???] Perfect, [???] Distinct Color:brown, green, greenish brown, greenish black, or dark green. Density:3 - 3.47, Average = 3.23 Diaphaniety:Translucent to opaque Habits:Columnar - Forms columns, Massive - Fibrous - Distinctly fibrous fine-grained forms., Massive - Granular - Common texture observed in granite and other igneous rock. Hardness:5-6 - Between Apatite and Orthoclase Luminescence:Non-fluorescent. Luster:Vitreous - Pearly Streak:whiteMore details...