Winchite

General Information: Chemical Formula:[ ](CaNa)Mg4(AL,Fe+++)Si8O22(OH)2 Composition:(Molecular Weight = 805.17 gm)Sodium 2.86 % NaCalcium 4.98 % CaMagnesium 12.07 % MgAluminum 2.51 % AlIron 1.73 % FeSilicon 27.91 % SiHydrogen 0.25 % H Oxygen 47.69 % O  Empirical Formula: CaNaMg4Al0.75Fe3+0.25(Si8O22)(OH)2 IMA Status:Approved IMA 1978 Name Origin:Named for Howard J. Winch, Geological survey of India.Physical Properties: Cleavage:[110] Good, [110] Good Color:blue violet or cobalt blue. Density:2.97 Diaphaniety:Translucent to Subopaque Hardness:5-6 - Between Apatite and Orthoclase Luster:Vitreous (Glassy) Streak:bluish whiteMore details...