Thomasclarkite-(Y)

General Information: Chemical Formula:(Na,Ce)(Y,REE)(HCO3)(OH)3·4H2O Composition:(Molecular Weight = 375.77 gm)La,Ce,Pr,Nd,Sm,26.83 % RESodium 4.89 % NaCerium 7.46 % CeYttrium 11.83 % Y Hydrogen 3.22 % H Carbon 3.20 % C Oxygen 42.58 % O  Empirical Formula: Na0.8Ce0.2Y0.5REE0.7(HCO3)(OH)3·4(H2O) Environment:Occurs as a late hydrothermal phase in alkaline pegmatite dikes in nepheline syenite. IMA Status:Approved IMA 1998 (Dana # Added) Locality:Poudrette quarry, Mont Saint-Hilaire, Quebec, Canada. Name Origin:Named after Thomas Henry Clark (1893-1996), McGill University, Montreal, Quebec, Canada, noted for his studies of the geology of the St. Lawrence Lowlands.Physical Properties: Cleavage:[010] Perfect, [101] Parting Color:white or yellow. Density:2.3 Diaphaniety:Translucent to transparent Habits:Pseudo Tetragonal - Crystals show a tetragonal shape., , Hardness:2-3 - Gypsum-Calcite Luminescence:Non-fluorescent. Luster:Vitreous (Glassy) Streak:whiteMore details...