Browsing by Author "Belakovskiy, Dmitriy I."

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    Eleonorite, Fe3+6 (PO4)4O(OH)4·6H2O : validation as a mineral species and new data.
    (2017) Chukanov, Nikita V.; Aksenov, Sergey M.; Rastsvetaeva, Ramiza K.; Schäfer, Christof; Pekov, Igor V.; Belakovskiy, Dmitriy I.; Cipriano, Ricardo Augusto Scholz; Oliveira, Luiz Carlos Alves de; Britvin, Sergey N.
    Eleonorite, ideally Fe3þ 6 (PO4)4O(OH)4·6H2O, the analogue of beraunite Fe2+Fe3þ 5 (PO4)4(OH)5·6H2O with Fe2+ completely substituted by Fe3+, has been approved by the International Mineralogical Association Commission on New Minerals, Nomenclature and Classification as a mineral species (IMA 2015-003). The mineral was first described on material from the Eleonore Iron mine, Dünsberg, near Giessen, Hesse, Germany, but during this study further samples were required and a neotype locality is the Rotläufchen mine, Waldgirmes, Wetzlar, Hesse, Germany, where eleonorite is associated with goethite, rockbridgeite, dufrénite, kidwellite, variscite, matulaite, planerite, cacoxenite, strengite and wavellite. Usually eleonorite occurs as red-brown prismatic crystals up to 0.2 mm × 0.5 mm × 3.5 mm in size and in random or radial aggregates up to 5 mm across encrusting cavities in massive ‘limonite’. The mineral is brittle. Its Mohs hardness is 3. Dmeas = 2.92(1), Dcalc = 2.931 g cm–3 . The IR spectrum is given. Eleonorite is optically biaxial (+), α = 1.765(4), β = 1.780(5), γ = 1.812(6), 2Vmeas = 75(10)°, 2Vcalc = 70°. The chemical composition (electron microprobe data, H2O analysed by chromatography of products of ignition at 1200°C, wt.%) is: Al2O3 1.03, Mn2O3 0.82, Fe2O3 51.34, P2O5 31.06, H2O 16.4, total 99.58. All iron was determined as being trivalent from a Mössbauer analysis. The empirical formula (based on 27 O apfu) is (Fe3þ 5:76Al0.18Mn3þ 0:09)Σ6.03(PO4)3.92O(OH)4.34·5.98H2O. The crystal structure (R = 0.0633) is similar to that of beraunite and is based on a heteropolyhedral framework formed by M(1–4)Ø6-octahedra (where M = Fe3+; Ø=O2– , OH– or H2O) and isolated PO4 tetrahedra, with a wide channel occupied by H2O molecules. Eleonorite is monoclinic, space group C2/c, a = 20.679(10), b = 5.148(2), c = 19.223(9) Å, β = 93.574(9)°, V = 2042.5(16) Å3 and Z = 4. The strongest reflections of the powder X-ray diffraction pattern [d,Å (I,%) (hkl)] are 10.41 (100) (200), 9.67 (38) (002), 7.30 (29) (202), 4.816 (31) (111, 004), 3.432 (18) (600, 114, 404, 313), 3.197 (18) (510, 511, 006, 314, 602), 3.071 (34) (314, 115).
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    Ferrorhodonite, CaMn3Fe[Si5O15], a new mineral species from Broken Hill, New South Wales, Australia.
    (2016) Shchipalkina, Nadezhda V.; Chukanov, Nikita V.; Pekov, Igor V.; Aksenov, Sergey M.; McCammon, Catherine; Belakovskiy, Dmitriy I.; Britvin, Sergey N.; Koshlyakova, Natalya N.; Schäfer, Christof; Cipriano, Ricardo Augusto Scholz; Rastsvetaeva, Ramiza K.
    The new mineral ferrorhodonite, a Mn2+–Fe2+ ordered analogue of rhodonite with the idealized formula CaMn3Fe[Si5O15], was found in the manganese-rich metamorphic rocks of the Broken Hill Pb–Zn–Ag deposit, Yancowinna Co., New South Wales, Australia. Ferrorhodonite occurs as brownish red coarsely crystalline aggregates in association with galena, chalcopyrite, spessartine, and quartz. The mineral is brittle. Its Mohs hardness is 6. Cleavage is perfect on {201} and good on {021} and {210}. The measured and calculated values of density are 3.71 (2) and 3.701 g cm−3, respectively. Ferrorhodonite is optically biaxial positive, with α = 1.731 (4), β = 1.736 (4), γ = 1.745 (5) and 2 V (meas.) = 80 (10)°. The average chemical composition of ferrorhodonite is (electronmicroprobe data, wt%): CaO 7.09, MgO 0.24, MnO 32.32, FeO 14.46, ZnO 0.36, SiO2 46.48, and total 100.95. The empirical formula calculated on 15 O apfu (Z = 2) is Ca0 . 81Mn2.92Fe1.29Mg0.04Zn0.03Si4.96O15. The Mössbauer and IR spectra are reported. The strongest reflections in the powder X-ray diffraction pattern [(d, Å (I, %) (hkl)] are: 3.337 (32) (−1–13), 3.132 (54) (−210), 3.091 (41) (0–23), 2.968 (100) (−2–11), 2.770 (91) (022), 2.223 (34) (−204), 2.173 (30) (−310). Ferrorhodonite is isostructural with rhodonite. The crystal structure was solved based on single-crystal X-ray diffraction data and refined to R1 = 4.02% [for 3114 reflections with I > 2σ(I)]. The mineral is triclinic, space group P ¯ 1, a = 6.6766 (5), b = 7.6754 (6), c = 11.803 (1) Å, α = 105.501 (1)°, β = 92.275 (1)°, γ = 93.919 (1)°; V = 580.44 (1). The crystal-chemical formula of ferrorhodonite inferred to be: M5(Ca0.81Mn0.19) M1−3(Mn2.52Fe0.48) M4(Fe20.+81Mn0.12Mg0.04Zn0.03) [Si5O15]. .
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    Magnesiovoltaite, K2Mg5Fe3+3Al(SO4)12·18H2O, a new mineral from the Alcaparrosa mine, Antofagasta region, Chile.
    (2016) Chukanov, Nikita V.; Aksenov, Sergey M.; Rastsvetaeva, Ramiza K.; Möhn, Gerhard; Rusako, Vyacheslav S.; Pekov, Igor V.; Cipriano, Ricardo Augusto Scholz; Eremina, Tatiana A.; Belakovskiy, Dmitriy I.; Lorenz, Joachim A.
    Magnesiovoltaite, a new voltaite-group mineral, was discovered in the Alcaparrosa mine, Cerro Alcaparrosa, El Loa province, Antofagasta region, Chile, in two associations, one of which includes coquimbite, tamarugite, alum-(Na), rhomboclase, yavapaiite, voltaite and opal, and the other one is botryogen, opal, tamarugite, alum-(K), pickeringite, magnesiocopiapite, and jarosite. Magnesiovoltaite forms yellow, brownish-yellow or pale yellowish-greenish isometric crystals up to 2 mm across. The main crystal forms are {111} and {100}; the subordinate forms are {110} and {211}. The new mineral is brittle, with subconchoidal fracture; cleavage is not observed. Mohs’ hardness is 2½. Dmeas = 2.51(2) g/cm3, Dcalc = 2.506 g/cm3. Magnesiovoltaite is optically anomalously anisotropic, uniaxial with ε = 1.584(2) and ω = 1.588(2), or biaxial (–) with α = 1.584(2), β = 1.587(2), and γ = 1.588 (2). Possible causes of the optical anomalies are discussed. The infrared spectrum is given. The chemical composition is (EDS-mode electron microprobe, all iron is considered as Fe3+ in accordance with Mössbauer data, H2O by gas chromatography of ignition products, wt. %): Na2O 0.13, K2O 4.64, MgO 9.13, MnO 1.73, ZnO 0.84, Al2O3 2.47, Fe2O3 13.36, SO3 50.83, H2O 17.6, total 100.73. The empirical formula based on 66 O atoms per formula unit (apfu) is (K1.85Na0.08)(Mg4.25Mn0.46Zn0.14)Fe3+ 3.14Al0.91(SO4) 11.91(H2O)18.325O0.035. The simplified formula is K2Mg5Fe3+ 3Al(SO4)12·18H2O. The crystal structure has been refined to R = 3.2% using 1147 unique reflections with I > 2σ(I). Magnesiovoltaite is cubic, Fd–3c, a = 27.161(1) Å, V = 20038(2) Å3, and Z = 16. Magnesiovoltaite is isostructural with other cubic voltaite-group minerals. The strongest lines of the powder X-ray diffraction pattern [d, Å (I, %) (hkl)] are: 9.56 (29) (022), 6.77 (37) (004), 5.53 (61) (224), 3.532 (68) (137), 3.392 (100) (008), 3.034 (45) (048), 2.845 (30) (139). The type material is deposited in the collections of the Fersman Mineralogical Museum of the Russian Academy of Sciences, Moscow, Russia.
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    Metavivianite, Fe2+Fe3+2(PO4)2(OH)2 6H2O : new data and formula revision.
    (2012) Chukanov, Nikita V.; Cipriano, Ricardo Augusto Scholz; Aksenov, Sergey M.; Rastsvetaeva, Ramiza K.; Pekov, Igor V.; Belakovskiy, Dmitriy I.; Krambrock, Klaus Wilhelm Heinrich; Paniago, Roberto Magalhães; Righi, Ariete; Martins, R. F.; Belotti, Ricardo Augusto; Bermanec, Vladimir
    The composition, structure, X-ray powder diffraction pattern, optical properties, density, infrared, Raman and Mo¨ssbauer spectra, and thermal properties of a homogeneous sample of metavivianite from the Boa Vista pegmatite, near Galile´ia, Minas Gerais, Brazil are reported for the first time. Metavivianite is biaxial (+) with a = 1.600(3), b = 1.640(3), g = 1.685(3) and 2Vmeas = 85(5)º. The measured and calculated densities are Dmeas = 2.56(2) and Dcalc = 2.579 g cm 3. The chemical composition, based on electronmicroprobe analyses, Mo¨ssbauer spectroscopy (to determine the Fe2+:Fe3+ ratio) and gas chromatography (to determine H2O) is MgO 0.70, MnO 0.92, FeO 17.98, Fe2O3 26.60, P2O5 28.62, H2O 26.5; total 101.32 wt.%. The empirical formula is (Fe3+ 1.64Fe2+ 1.23Mg0.085Mn0.06)S3.015(PO4)1.98(OH)1.72·6.36H2O. Metavivianite is triclinic, P1¯ , a = 7.989(1), b = 9.321(2), c = 4.629(1) A ˚ , a = 97.34(1), b = 95.96(1), g = 108.59(2)º, V = 320.18(11) A ˚ 3 and Z = 1. The crystal structure was solved using a single-crystal techniques to an agreement index R = 6.0%. The dominant cations in the independent sites are Fe2+ and Fe3+, with multiplicities of 1 and 2, respectively. The simplified crystal-chemical formula for metavivianite is Fe2+(Fe3+,Fe2+)2(PO4)2(OH,H2O)2·6H2O; the endmember formula is Fe2+Fe3+ 2 (PO4)2(OH)2·6H2O, which is dimorphous with ferrostrunzite.