Showing results 81 to 100 of 184
  Karsts in sandstones and quartzites of Minas Gerais, BrazilWillems, Luc  ; ; et alin Cadernos Laboratorio Xeologico de Laxe Coruña (2008), 33 Detailed reference viewed: 13 (0 ULg)Omongwaite, Na2Ca5(SO4)6.3H2O, a new mineral from recent salt lake deposits, Namibia; Hatert, Frédéric ; in Mineralogical Magazine (2008), 72 Detailed reference viewed: 30 (1 ULg)The crystal structure of sursassite from the Lienne valley, Stavelot Massif, BelgiumHatert, Frédéric ; Fransolet, André-Mathieu ; et alin European Journal of Mineralogy (2008), 20 Detailed reference viewed: 15 (1 ULg)The IMA-CNMNC dominant-constituent rule revisited and extendedHatert, Frédéric ; in Canadian Mineralogist (2008), 46 Detailed reference viewed: 17 (0 ULg)Apatite-(CaOH) in the fossil bat guano deposit from the "dry" Cioclovina Cave, Şureanu Mountains, Romania; ; et al in Canadian Mineralogist (2008), 46 Detailed reference viewed: 25 (0 ULg)The crystal chemistry of the divalent cation in alluaudite-type phosphates : a structural and infrared spectral study of the Na1.5(Mn1-xM2+x)1.5Fe1.5(PO4)3 solid solutions (x = 0 to 1, M2+ = Cd2+, Zn2+)Hatert, Frédéric in Journal of Solid State Chemistry (2008), 181 Detailed reference viewed: 19 (1 ULg)The sulfides and selenides of the Musonoï mine, Kolwezi, Katanga, Democratic Republic of Congo; Hatert, Frédéric in Canadian Mineralogist (2008), 46 Detailed reference viewed: 30 (1 ULg)Fe-2(II)(PO4)(OH), a synthetic analogue of wolfeiteHatert, Frédéric in Acta Crystallographica Section C-Crystal Structure Communications (2007), 63(Part 12), 119-121 This paper reports the hydrothermal synthesis and crystal structure refinement of diiron(II) phosphate hydroxide, Fe-2(II)(PO4)(OH), obtained at 1063 K and 2.5 GPa. This phosphate is the synthetic ... [more ▼] This paper reports the hydrothermal synthesis and crystal structure refinement of diiron(II) phosphate hydroxide, Fe-2(II)(PO4)(OH), obtained at 1063 K and 2.5 GPa. This phosphate is the synthetic analogue of the mineral wolfeite, and has a crystal structure topologically identical to those of minerals of the triplite-triploidite group. The complex framework contains edge-and corner-sharing FeO4(OH) and FeO4(OH)(2) polyhedra, linked via corner-sharing to the PO4 tetrahedra (average P-O distances are between 1.537 and 1.544 angstrom). Four five-coordinated Fe sites are at the centers of distorted trigonal bipyramids (average Fe-O distances are between 2.070 and 2.105 angstrom), whereas the coordination environments of the remaining Fe sites are distorted octahedra (average Fe-O distances are between 2.146 and 2.180 angstrom). The Fe-O distances are similar to those observed in natural Mg-rich wolfeite, except for two Fe-O bond distances, which are significantly longer in synthetic Fe-2(2+) (PO4)(OH). [less ▲] Detailed reference viewed: 24 (0 ULg)Petrogenetic significance of the triphylite + sarcopside intergrowths in granitic pegmatites : an experimental investigation of the Li(Fe,Mn)(PO4)-(Fe,Mn)3(PO4)2 systemHatert, Frédéric ; Roda-Robles, Encarnacion ; et alConference (2007) Detailed reference viewed: 6 (0 ULg)Alteration sequences of aluminium phosphates from Montebras pegmatite, Massif Central, France; Hatert, Frédéric ; Fransolet, André-Mathieu Poster (2007) Detailed reference viewed: 4 (0 ULg)Occurrence of sursassite in the Lienne valley, Stavelot Massif, Belgian ArdennesFransolet, André-Mathieu ; Hatert, Frédéric ; Bernhardt, Heinz-Jürgen et alConference (2007) Detailed reference viewed: 11 (1 ULg)The structural complexity of phosphates in the Na-Fe(II)-Fe(III) (+ PO4) systemHatert, Frédéric Conference (2007) Detailed reference viewed: 2 (0 ULg)New structural data on synthetic alluaudite-type phosphatesRondeux, Mélanie ; Hatert, Frédéric ; Fransolet, André-Mathieu Poster (2007) Detailed reference viewed: 6 (0 ULg)Karsts in sandstones and quatrzites of Minas Gerais, BrazilWillems, Luc ; ; et alPoster (2007) Detailed reference viewed: 15 (0 ULg)Gengenbachit, KFe3(H2PO4)2(HPO4)4.6H2O, ein zweites neues Phosphatmineral von der Grube Silberbrünnle bei Gengenbach, im mittleren Schwarzwald, nunmehr eine anerkannte neue Mineralart; Theye, Thomas ; Hatert, Frédéric in Der Aufschluss (2007), 58 Detailed reference viewed: 19 (5 ULg)Etude lithologique de la colonne du Boultè et nouvelles hypothèses sur sa provenanceNekrassoff, Serge ; Hatert, Frédéric ; Boulvain, Frédéric et alin Hautes Fagnes (2007), 2007-2 Detailed reference viewed: 10 (0 ULg)Crystal structure of trisodium iron diphosphate, Na2.88Fe(PO4)(2), a synthetic phosphate with hannayite-type heteropolyhedral chainsHatert, Frédéric in Zeitschrift für Kristallographie. New Crystal Structures (2007), 222(1), 6-8 FeNa2.88O8P2, triclinic, P (1) over bar (no. 2), a 5.3141(6) b = 8.5853(9) angstrom, c = 8.7859(8) angstrom, alpha = 114.429(9)degrees, beta = 92.327(9)degrees, gamma = 106.08(1)degrees, V = 345.1 ... [more ▼] FeNa2.88O8P2, triclinic, P (1) over bar (no. 2), a 5.3141(6) b = 8.5853(9) angstrom, c = 8.7859(8) angstrom, alpha = 114.429(9)degrees, beta = 92.327(9)degrees, gamma = 106.08(1)degrees, V = 345.1 angstrom(3),Z = 2, Rgt(F) = 0.028, wR(ref)(F-2) = 0.087, T = 293 K. [less ▲] Detailed reference viewed: 40 (5 ULg) La titanite de Bertrix et les minéraux associés.Rondeux, Mélanie ; Hatert, Frédéric in Bulletin de la Société Royale des Sciences de Liège (2007), 76 Detailed reference viewed: 16 (1 ULg)Pumpellyite-(Al), a new mineral from Bertrix, Belgian ArdennesHatert, Frédéric ; ; et alin European Journal of Mineralogy (2007), 19(2, MAR-APR), 247-253 Pumpellyite-(Al), ideally Ca-2(Al,Fe2+,Mg)Al-2(SiO4)(Si2O7)(OH,O)(2)center dot H2O, is a newly approved mineral species from Bertrix, Ardennes mountains, Belgium. It occurs as radiating fibrous aggregates ... [more ▼] Pumpellyite-(Al), ideally Ca-2(Al,Fe2+,Mg)Al-2(SiO4)(Si2O7)(OH,O)(2)center dot H2O, is a newly approved mineral species from Bertrix, Ardennes mountains, Belgium. It occurs as radiating fibrous aggregates reaching 5 mm in diameter, constituted by acicular crystals associated with calcite, K-feldspar and chlorite. Pumpellyite-(Al) is transparent to translucent and exhibits an emerald-green to white colour, sometimes with bluish tinges. The lustre is vitreous and the streak is colourless. The mineral is non-fluorescent, brittle, and shows a perfect {100} cleavage. The estimated Mobs hardness is 51/2, and the calculated density is 3.24 g/cm(3). Pumpellyite-(Al) is biaxial positive, alpha = 1.678(2), beta = 1.680(2), gamma = 1.691 (1) (lambda = 590 nm), colourless in thin section, 2V = 46 degrees, Y = b, no dispersion. Electron-microprobe analyses gave SiO2 37.52, Al2O3 25.63, MgO 1.99, FeO 4.97, MnO 0.11, CaO 23.21, BaO 0.01, Na2O 0.03, K2O 0.02, H2Ocalc. 6.71, total 100.20 wt. %. The resulting empirical formula, calculated on the basis of 8 cations, is (Ca1.99Na0.01)(Sigma 2.00)(Al0.42Fe0.332+Mg0.24Mn0.01)(Sigma 1.00)Al-2.00(SiO4)(Si2O7)(2.42) center dot 0.58H(2)O. The simplified formula is Ca2AlAl2(SiO4)(Si2O7)(OH)(3), which requires SiO2 38.16, Al2O3 32.38, CaO 23.74, H2O 5.72, Total 100.00 wt. %. The unit-cell parameters, refined from X-ray powder diffraction data, are: a = 8.818(2), b = 5.898(2), c = 19.126(6) angstrom, beta = 97.26(3)degrees, V = 986.7(4) angstrom(3), space group A2/m. The eight strongest lines in the powder pattern [d-values(in angstrom)(I)(hkl)] are: 4.371(65)(200), 3.787(80)(202), 3.040(70)(204), 2.912(95)(300), 2.895(100)(30 (2) over bar), 2.731(40)(20 (6) over bar), 2.630(35)(31 (1) over bar), 2.191(45)(40 (2) over bar). Pumpellyite-(Al) belongs to the pumpellyite group, and corresponds to the Al-rich compositions where the M1 and M2 sites contain Al as predominant cation. The crystal structure of pumpellyite-(Al) has been refined by the Rietveld method, based on an X-ray powder diffraction pattern, to R-Bragg = 7.09 %. The infrared spectrum is similar to those of minerals of the pumpellyite group. The mineral species and name were approved by the Commission on New Minerals and Mineral Names, IMA (no. 2005-016). [less ▲] Detailed reference viewed: 37 (0 ULg)The stability of primary alluaudites in granitic pegmatites: an experimental investigation of the Na-2(Mn2-2x Fe1+2x )(PO4)(3) systemHatert, Frédéric ; Fransolet, André-Mathieu ; in Contributions to Mineralogy & Petrology (2006), 152(4), 399-419 In order to assess the geothermometric potential of the Na-2(Mn2-2x Fe1+2x )(PO4)(3) system (x = 0-1), which represents the compositions of natural weakly oxidized alluaudites, we performed hydrothermal ... [more ▼] In order to assess the geothermometric potential of the Na-2(Mn2-2x Fe1+2x )(PO4)(3) system (x = 0-1), which represents the compositions of natural weakly oxidized alluaudites, we performed hydrothermal experiments between 400 and 800 degrees C, at 1 kbar, under an oxygen fugacity (f(O-2)) controlled by the Ni-NiO (NNO), Fe2O3-Fe3O4 (HM), Cu2O-CuO (CT), and Fe-Fe3O4 (MI) buffers. When f(O-2) is controlled by NNO, single-phase alluaudites crystallize at 400 and 500 degrees C, whereas the association alluaudite + maricite appears between 500 and 700 degrees C. The limit between these two fields corresponds to the maximum temperature that can be reached by alluaudites in granitic pegmatites, because maricite has never been observed in these geological environments. Because alluaudites are very sensitive to variations of oxygen fugacity, the field of hagendorfite, Na2MnFe2+Fe3+(PO4)(3), has been positioned in the f(O-2)-T diagram, and provides a tool that can be used to estimate the oxygen fugacity conditions that prevailed in granitic pegmatites during the crystallization of this phosphate. [less ▲] Detailed reference viewed: 19 (1 ULg) |
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