...M. D. Barton; H. T. Haselton; B. S. Hemingway; O. J. Kleppa; R. A. Robie Abstract The standard thermodynamic properties of fluor-topaz, Al 2 SiO 4 F 2 , have been calculated from low- and high-temperature heat-capacity measurements and from high-temperature, oxide-melt calorimetry. Fluor-topaz...

... Å apart, were located. The H sites are significantly displaced from the single one found in natural OH-bearing fluor-topaz and violate the mirror plane of space group Pbnm , at least locally. Although not resolved using X-ray data, the possibility of long-range order and the reduction of symmetry to Pbn 2...

... for topaz solid solutions and calculation of the thermodynamic properties of (hypothetical) hydroxyl–topaz. A proton-avoidance activity model agrees well with the experimental data and gives reasonable extrapolations to lower temperatures. Combined thermodynamic data for hydroxyl-topaz (OHT), fluor–topaz...

...Sari Lukkari; Rainer Thomas; Ilmari Haapala Abstract Nous avons évalué la cristallisation d’un magma granitique tardif, riche en fluor, dans le pluton de Kymi, sud-est de la Finlande, par refusion des reliquats magmatiques déjà cristallisés, piégés dans les grains de quartz et de topaze...

..., albite, fluor-elbaite, and K-feldspar extending from the host albite-lepidolite-topaz subunit are locally developed at the margin. Several textural/paragenetic types of the individual minerals in the PHC were distinguished from center to margin of the nodule and vugs. The minerals exhibit very...

... promotes further exsolution of H 2 O, which contributes to the formation of the miarolitic cavities ( Simmons et al . 2012 ). Tourmaline and topaz have the highest H 2 O contents in miarolitic cavity samples, supporting the idea that the fluids became more aqueous during evolution. Abundant fluor-schorl...

... intersecting highly fractionated, topaz–zinnwaldite S-type leucogranite. Fluorarrojadite-(BaNa) is associated with fluorapatite, ‘fluordickinsonite-(BaNa)’, triplite, viitaniemiite and minor amounts of other minerals. It forms fine-grained irregular aggregates up to 4 cm x 2 cm, which consist of individual...

.... For each trace element, baseline scattering paths were calculated from trace element-free fluor-topaz crystal structure parameters of Northrup et al. (1994) by the Artemis FEFF utility, with the trace element atom substituted for Si or Al as the absorbing atom in the distorted tetrahedral or octahedral...

.... , Hampar , M.S. , Zussman , J. ( 1979 ): An explanation of anomalous optical properties of topaz . Mineral. Mag ., 43 , 237 – 241 . Barton , M.D. , Haselton , H.T. , Hemingway , B.S. , Kleppa , O.J. , Robie , R.A. ( 1982 ): The thermodynamic properties of fluor-topaz...

... solution and some petrological applications . American Mineralogist , 67 , 956 – 974 . Barton , M.D. , Haselton , H.T. Jr. , Hemingway , B.S. , Kleppa , O.J. , and Robie , R.A. ( 1982 ) The thermodynamic properties of fluor-topaz . American Mineralogist , 67 , 350 – 355...

....%) and very rare, almost end-member, topaz associated with the Ca-bearing “fluor-elbaite” –rossmanite ( Černý et al . 1998 , Stilling 1998 ) indicates that the late Ca-enrichment is due to conservation of Ca during consolidation of the pegmatite by sequestering as fluoride-bearing complexes...

... et les conditions de croissance des topazes. Ces rhyolites, riches en silice et alcalins, sont méta-alumineuses à légèrement hyper-alumineuses. Elles sont enrichies en fluor et en éléments incompatibles comme Rb, Cs, Ta, U et Th et appauvries en Ba, Sr, Ca, Mg, Ti et Ni. De ce fait elles...

...Renata Čopjaková; Radek Škoda; Michaela Vašinová Galiová; Milan Novák; Jan Cempírek Abstract Primary black thick-prismatic Al-rich schorl to rare fluor-schorl (TurP1), locally overgrown by brownish-green Li-rich fluor-schorl to fluor-elbaite (TurP2) from the Kracovice pegmatite (mixed NYF+LCT...

... hydrotermales dans silicates fluores: topaze et zunyte . Chemical Geology , 12 , 257 – 269 . Beus A.A. Dikov Yu.P. ( 1967 ) The geochemistry of beryllium in the processes of endogenetic mineralization . Nedra, Moscow (in Russian). Burt D. ( 1981 ) Acidity-salinity diagram...

... tourmaline are bluish Mn-rich fluorapatite, quartz, feldspars, Mn-rich garnet (63 mol.% spessartine), pink Mn-bearing muscovite (up to 0.3 wt% MnO), topaz, cassiterite and rarely, beryl and bertrandite ( Ertl et al. 2003 , 2004 ). All Zambian tourmaline investigated consist of elbaite and “fluor...

... ) The thermodynamic propries of fluor-topaz . American Mineralogist , 67 , 350 – 355 . Beukes , G.J. , Slabbert , M.J. , Bruiyu , H. de., Botha , B.J.V. , Schoch , A.E. , and Van der Westhuizen , W.A. ( 1991 ) Ti-dumortierite from the Keimoes area, Namaqua mobile belt, South Africa...

... of the tourmaline-bearing lithologies. (a) Tourmaline-rich orbicule with leucocratic halo embedded in granite. Note coin for scale. (b) Reddish greisen zone enriched in quartz, muscovite, tourmaline, topaz, and hematite. Horizontal field of view is ∼1.5 m. Tourmaline is a crystallographically acentric...

.... Jr. Hemingway B.S. Kleppa O.J. Robie R.A. ( 1982 ) The thermodynamic properties of fluor-topaz . American Mineralogist , 67 , 350 – 355 . Baur W.H. ( 1974 ) The geometry of polyhedral distortions. Predictive relationships for the phosphate group . Acta Crystallographica...