Cation partitioning between minerals of the triphylite ± graftonite ± sarcopside association in granitic pegmatites

Conference (2011)

Crystal chemistry of lithium in pegmatite phosphates: A SIMS investigation of natural and synthetic samples

in Estudios Geologicos (2009), 19(2), 131-134

Crystal chemistry of natural and synthetic fillowite-type phosphates

Conference (2008)

Hydrothermal synthesis and crystal structure of Na(Na,Mn)(7)Mn-22(PO4)(18)0.5H(2)O, a new compound of fillowite structure type

in European Journal of Mineralogy (2006), 18(6), 765-774

The chemical compound Na(Na,Mn)(7)Mn-22(PO4)(18)center dot 0.5H(2)O was synthesized with a Tuttle pressure vessel at 800 degrees C and 1 kbar during experimental investigations on the conditions of ... [more ▼]

The chemical compound Na(Na,Mn)(7)Mn-22(PO4)(18)center dot 0.5H(2)O was synthesized with a Tuttle pressure vessel at 800 degrees C and 1 kbar during experimental investigations on the conditions of fillowite formation. The crystal structure of a single-crystal, space group R (No. 148), a = 15.2741(9), c = 43.334(3) angstrom, Z = 6, was determined from X-ray intensity data and refined up to R-1 = 0.0728 and R-l{FO > 4 sigma(FO)} = 0.0546. The crystal structure of Na(Na,Mn)(7)Mn-22(PO4)(18)center dot 0.5H(2)O is similar to the structure of fillowite, Na6Ca3(Mn,Fe)(21)(PO4)(18.), but a significant difference between the synthetic H2O containing compound and fillowite is the replacement of (Na12)O-8(-) by Mn(H2O)(2)O-5(-) polyhedra, which form characteristic six-member rings. The coordination polyhedra around Na12 and Mn12 are so different that simple isomorphous substitution of Na12 by Mn12 is very unlikely, but whole six-member rings either of (Na12)O-8(-) or (Mn12)(H2O)(2)O-5 polyhedra seem to be distributed statistically over the crystal structure. No indication for ordering, e.g. sheet by sheet, has been observed. Na(Na,Mn)(7)Mn-22(PO4)(18)center dot 0.5H(2)O is the first fillowite-like compound for which water is located in the structure from single-crystal study. This result is proved by infrared spectral data and indicates that water can play an essential role in the fillowite structure-type. Structural features of the synthetic compounds Na(Na,Mn)(7)Mn-22(PO4)(18)center dot 0.5H(2)O, Na4Ca4Mg21(PO4)(18) and fillowite are compared. [less ▲]

Ferrorosemaryite, NaFe2+Fe3+Al(PO4)3, a new phosphate mineral from the Rubindi pegmatite, Rwanda

Conference (2004)

First experimental evidence of alluaudite-like phosphates with high Li-content: the (Na1-xLix)MnFe2(PO4)3 series (x = 0 to 1).

in European Journal of Mineralogy (2000), 12