Masutomilite

General Information: Chemical Formula:K(Li,Al,Mn++)3[(Si,Al)4O10](F,OH)2 Composition:(Molecular Weight = 402.17 gm)Potassium 9.72 % K Lithium 3.45 % LiManganese 6.83 % MnAluminum 10.06 % AlSilicon 20.95 % SiHydrogen 0.13 % H Oxygen 41.77 % O Fluorine 7.09 % F  Empirical Formula: KLi2Al0.5Mn2+0.5Si3AlO10F1.5(OH)0.5 Environment:Li pegmatites. IMA Status:Approved IMA 1975 Locality:Tanakamiyama district, Shiga Prefecture, Honshu, Japan. Name Origin:Named for Kazunosuke Masutomi, Japanese pharmacist and prominent amateur mineralogist and mineral collector.Physical Properties: Cleavage:[001] Perfect Color:purple pink. Density:2.94 Diaphaniety:Transparent to Translucent Habits:Pseudo Hexagonal - Crystals show a hexagonal outline., , Hardness:2.5 - Finger Nail Luster:Vitreous - Pearly Streak:whiteMore details...

K(Li,Al,Mn)3(Si,Al)4O10(F,OH)2