Uvite

General Information: Chemical Formula:(Ca,Na)(Mg,Fe++)3Al5Mg(BO3)3Si6O18(OH,F)4 Composition:(Molecular Weight = 970.23 gm)Sodium 0.59 % NaCalcium 3.10 % CaMagnesium 5.64 % MgAluminum 13.90 % AlIron 4.32 % FeSilicon 17.37 % SiBoron 3.34 % B Hydrogen 0.31 % H Oxygen 49.47 % O Fluorine 1.96 % F  Empirical Formula: Ca0.75Na0.25Mg2.25Fe2+0.75Al5(BO3)3Si6O18(OH)3F Environment:Pegmatitic and skarn rocks. Locality:Province Uva, Sri Lanka. Name Origin:Named after its locality.Physical Properties: Cleavage:[1011] Indistinct Color:yellowish brown, brown, blackish brown, or bluish black. Density:3.1 - 3.2, Average = 3.15 Diaphaniety:Translucent to opaque Habits:Striated - Parallel lines on crystal surface or cleavage face., Prismatic - Crystals Shaped like Slender Prisms (e.g. tourmaline)., Hardness:7.5 - Garnet Luminescence:Piezoelectric. Luster:Vitreous - Greasy Streak:light brownMore details...