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Chukanov N.V.,RAS Institute of Problems of Chemical Physics | Aksenov S.M.,Russian Academy of Sciences | Pekov I.V.,Moscow State University | Ternes B.,Bahnhofstrasse 45 | And 4 more authors.
Geology of Ore Deposits | Year: 2014

A new mineral, ferroindialite, a Fe2+-dominant analog of indialite, has been found in a pyrometamorphosed xenolith of pelitic rock hosted in alkaline basalts. Associated minerals are phlogopite, sanidine, sillimanite, pyroxenes of the enstatite-ferrosilite series, wagnerite, fluorapatite, tridymite, zircon and almandine. Ferroindialite forms brown-purple to gray with a violet-blue tint short prismatic or thick tabular hexagonal crystals up to 1.5 mm in size. The new mineral is brittle, with a Mohs’ hardness of 7. Cleavage is not observed. Dmeas = 2.66(1), Dcalc = 2.667 g/cm3. IR spectrum shows neither H2O nor OH groups. Ferroindialite is anomalously biaxial (−), α = 1.539(2), β = 1.552(2), γ = 1.554(2), 2Vmeas = 30(10)°. The mineral is weakly pleochroic, ranging from colorless on X to pale violet on Z. Dispersion is weak, r < v. The chemical composition (electron microprobe, mean of five point analyses, wt %) is as follows: 0.14 Na2O, 0.46 K2O, 4.95 MgO, 1.13 MnO, 12.66 FeO, 2.64 Fe2O3, 30.45 Al2O3, 47.22 SiO2, total is 99.65. The distribution of total iron content between Fe2+ and Fe3+ was carried out according to structural data. The empirical formula of ferroindialite is: (K0.06Na0.03)(Fe1.12 2+Mg0.78Mn0.10)Σ2.00(Al3.79Fe0.21 3+)Σ4.00Si4.98O18. The simplified formula is: (Fe2+,Mg)2Al4Si5O18. The crystal structure has been refined on a single crystal, R = 0.049. Ferroindialite is hexagonal, space group P6/mcc; a = 9.8759(3), c = 9.3102(3) Å, V = 786.40(3) Å3, Z = 2. The strongest lines in the X-ray powder diffraction pattern [d, Å (I, %) (hkl)] are: 8.59 (100) (100), 4.094 (27) (102), 3.390 (35) (112), 3.147 (19) (202), 3.055 (31) (211), 2.657 (12) (212), 1.695 (9) (224). The type specimen of ferroindialite is deposited in the Fersman Mineralogical Museum, Russian Academy of Sciences, Moscow, registration number 4400/1. © 2014, Pleiades Publishing, Ltd. Source


Chukanov N.V.,RAS Institute of Problems of Chemical Physics | Pekov I.V.,Moscow State University | Rastsvetaeva R.K.,Institute of Crystallography | Aksenov S.M.,Institute of Crystallography | And 5 more authors.
European Journal of Mineralogy | Year: 2012

The new Mg-and F-dominant lamprophyllite-group mineral lileyite (IMA 2011-021) was found at the Löhley quarry, Üdersdorf, near Daun, Eifel Mountains, Rhineland-Palatinate (Rheinland-Pfalz), Germany, and named for the old name of the type locality, Liley. Associated minerals are nepheline, leucite, augite, magnetite, fluorapatite, perovskite, götzenite. Lileyite is brown, translucent; streak is white. It forms platy crystals up to 0.1 × 0.3 × 0.5 mm in size and their clusters up to 1 mm across on the walls of cavities in an alkaline basalt. Lileyite is brittle, with Mohs hardness of 3-4 and perfect cleavage on (001). D calc is 3.776 g/cm 3. The new mineral is biaxial (+), α = 1.718(5), β = 1.735(5), γ = 1.755(5), 2V (meas.) = 75(15), 2V (calc.) = 86°. The IR spectrum is given. The chemical composition is (EDS-mode electron microprobe, mean of 5 analyses, wt%): SiO 2 28.05, BaO 26.39, TiO 2 18.53, Na 2O 6.75, MgO 4.58, FeO 4.48, CaO 2.30, SrO 2.23, MnO 1.44, K iO 1.41, Nb 2O 5 0.95, F 3.88, -O=F 2 -1.63; total 99.36. The empirical formula based on 18 anions is: Ba 1.50Sr 0.19K 0.26Na 1.89Ca 0.36Mn 0.18Mg 0.99Fe 0.54Ti 2.01Nb 0.06Si 4.06O 16.23F 1.77. The simplified formula is: Ba 2(Na,Fe,Ca) 3MgTi 2(Si 2O 7) 2O 2F 2. The crystal structure was solved using single-crystal X-ray diffraction data (R = 0.024). Lileyite is monoclinic, space group C2/m, α = 19.905(1), β = 7.098(1), c = 5.405(1) Å , β = 96.349(5) V =758.93(6) Å 3, Z = 2. The strongest lines of the powder diffraction pattern [d, Å (I, %) (hkl)] are: 3.749 (45) (31-1), 3.464 (76) (510, 311, 401), 3.045 (37) (51-1), 2.792 (100) (221, 511), 2.672 (54) (002, 601, 20-2), 2.624 (43) (710, 42-1). Type material is deposited in the collections of the Fersman Mineralogical Museum of the Russian Academy of Sciences, Moscow, Russia, registration number 4106/1. © 2011 E. Schweizerbart'sche Verlagsbuchhandlung. Source


Chukanov N.V.,RAS Institute of Problems of Chemical Physics | Pekov I.V.,Moscow State University | Rastsvetaeva R.K.,Russian Academy of Sciences | Aksenov S.M.,Russian Academy of Sciences | And 4 more authors.
Geology of Ore Deposits | Year: 2013

Osumilite-(Mg), the Mg-dominant analogue of osumilite, has been approved by the CNMNC IMA as a new mineral species. The holotype sample has been found at Bellerberg, Eifel volcanic area, Germany. Fluorophlogopite, sanidine, cordierite, mullite, sillimanite, topaz, pseudobrookite and hematite are associated minerals. Osumilite-(Mg) occurs as short prismatic or thick tabular hexagonal crystals reaching 0.5 × 1 mm in size in the cavities in basaltic volcanic glasses at their contact with thermally metamorphosed xenoliths of pelitic rocks. The mineral is brittle, with Mohs' hardness 6.5. Cleavage was not observed. Color is blue to brown. D meas = 2.59(1), D calc = 2.595 g/cm3. No bands corresponding to H2O and OH-groups are in the IR spectrum. Osumilite-(Mg) is uniaxial (+), ω = 1.539(2), e{open} = 1.547(2). The chemical composition (electron microprobe, average of 5 point analyses, wt %) is: 0.08 Na2O, 3.41 K2O, 0.04 CaO, 7.98 MgO, 0.28 MnO, 21.57 Al2O3, 3.59 Fe2O3, 62.33 SiO2, total 99.28. The empirical formula is: (K0.72Na0.03Ca0.01)(Mg1.97Mn0.04)[Al4.21Fe 0.45 3+ Si10.32]O30. The simplified formula is: KMg2Al3(Al2Si10)O10. The crystal structure was refined on a single crystal, R = 0.0294. Osumilite-(Mg) is hexagonal, space group P6/mcc; a = 10.0959(1), c = 14.3282(2)Å, V = 1264.79(6) Å3, Z = 2. The strongest reflections in the X-ray powder diffraction pattern [d, Å I %) (hkl)] are: 7.21 (37) (002), 5.064 (85) (110), 4.137 (45) (112), 3.736 (43) (202), 3.234 (100) (211), 2.932 (42) (114), 2.767 (51) (204). A type specimen is deposited in the Fersman Mineralogical Museum, Russian Academy of Sciences, Moscow, registration number 4174/1. © 2013 Pleiades Publishing, Ltd. Source


Chukanov N.V.,RAS Institute of Problems of Chemical Physics | Aksenov S.M.,Russian Academy of Sciences | Rastsvetaeva R.K.,Russian Academy of Sciences | Van K.V.,Russian Academy of Sciences | And 5 more authors.
Geology of Ore Deposits | Year: 2015

A new mineral, mendigite (IMA no. 2014-007), isostructural with bustamite, has been found in the In den Dellen pumice quarry near Mendig, Laacher Lake area, Eifel Mountains, Rhineland-Palatinate (Rheinland-Pfalz), Germany. Associated minerals are sanidine, nosean, rhodonite, tephroite, magnetite, and a pyrochlore-group mineral. Mendigite occurs as clusters of long-prismatic crystals (up to 0.1 × 0.2 × 2.5 mm in size) in cavities within sanidinite. The color is dark brown with a brown streak. Perfect cleavage is parallel to (001). Dcalc = 3.56 g/cm3. The IR spectrum shows the absence of H2O and OH groups. Mendigite is biaxial (–), α = 1.722 (calc), β = 1.782(5), γ = 1.796(5), 2Vmeas = 50(10)°. The chemical composition (electron microprobe, mean of 4 point analyses, the Mn2+/Mn3+ ratio determined from structural data and charge-balance constraints) is as follows (wt %): 0.36 MgO, 10.78 CaO, 37.47 MnO, 2.91 Mn2O3, 4.42 Fe2O3, 1.08 Al2O3, 43.80 SiO2, total 100.82. The empirical formula is Mn2.00(Mn1.33Ca0.67) (Mn0.50 2+ Mn0.28 3+ Fe0.15 3+ Mg0.07)(Ca0.80 (Mn0.20 2+)(Si5.57 Fe0.27 3+ Al0.16O18). The idealized formula is Mn2Mn2MnCa(Si3O9)2. The crystal structure has been refined for a single crystal. Mendigite is triclinic, space group (Formula presented.); the unit-cell parameters are a = 7.0993(4), b = 7.6370(5), c = 7.7037(4) Å, α = 79.58(1)°, β = 62.62(1)°, γ = 76.47(1)°; V = 359.29(4) Å3, Z = 1. The strongest reflections on the X-ray powder diffraction pattern [d, Å (I, %) (hkl)] are: 3.72 (32) (020), 3.40 (20) (002, 021), 3.199 (25) (012), 3.000 (26), ((Formula presented.), (Formula presented.)), 2.885 (100) (221, (Formula presented.)), 2.691 (21) (222, $2\bar 10$), 2.397 (21) ((Formula presented.), 203, 031), 1.774 (37) (412, (Formula presented.). The type specimen is deposited in the Fersman Mineralogical Museum, Russian Academy of Sciences, Moscow, registration number 4420/1. © 2015, Pleiades Publishing, Ltd. Source


Pekov I.V.,Moscow State University | Chukanov N.V.,RAS Institute of Problems of Chemical Physics | Britvin S.N.,Saint Petersburg State University | Kabalov Y.K.,Moscow State University | And 6 more authors.
Mineralogical Magazine | Year: 2012

Hielscherite, ideally Ca3Si(OH)6(SO 4)(SO3)•11H2O, (IMA 2011-037) is the first ettringite-group mineral with essential sulfite. We have identified a continuous natural solid-solution series from endmember thaumasite, Ca 3Si(OH)6(SO4)(CO3)•12H 2O, to a composition with at least 77 mol.% endmember hielscherite. In this series, the SO3:CO3 ratio is variable, whereas the SO4 content remains constant. Compositions with more than 50 mol.% endmember hielscherite have only been found at Graulay quarry near Hillesheim in the western Eifel Mountains, Rhineland-Palatinate, where they occur with phillipsite-K, chabazite-Ca and gypsum in cavities in alkaline basalt. Sulfite-rich thaumasite has been found in hydrothermal assemblages in young alkaline basalts in two volcanic regions of Germany: it is widespread at Graulay quarry and occurs at Rother Kopf, Schellkopf and Bellerberg quarries in Eifel district; it has also been found at Zeilberg quarry, Franconia, Bavaria. Hielscherite forms matted fibrous aggregates up to 1 cm across and groups of acicular to prismatic hexagonal crystals up to 0.3 × 0.3 × 1.5 mm. Individual crystals are colourless and transparent with a vitreous lustre and crystal aggregates are white with a silky lustre. The Mohs hardness is 2-2½. Measured and calculated densities are D meas = 1.82(3) and D calc = 1.79 g cm-3. Hielscherite is optically uniaxial (-), ω = 1.494(2), ε = 1.476(2). The mean chemical composition of holotype material (determined by electron microprobe for Ca, Al, Si, and S and gas chromatography for C, H and N, with the S 4+:S6+ ratio from the crystal-structure data) is CaO 27.15, Al2O3 2.33, SiO2 7.04, CO2 2.71, SO2 6.40, SO3 12.91, N2O5 0.42, H2O 39.22, total 98.18 wt.%. The empirical formula on the basis of 3 Ca atoms per formula unit is Ca3(Si0.73Al 0.28)Σ1.01(OH)5.71(SO4) 1.00(SO3)0.62(CO3) 0.38(NO3)0.05•10.63H2O. The presence of sulfite was confirmed by crystal-structure analysis and infrared and X-ray absorption near edge structure spectra. The crystal structure of sulfite-rich thaumasite from Zeilberg quarry was solved by direct methods based on single-crystal X-ray diffraction data (R 1 = 0.064). The structure of hielscherite was refined using the Rietveld method (R w p = 0.0317). Hielscherite is hexagonal, P63, a = 11.1178(2), c = 10.5381(2) Å, V = 1128.06(4) Å3 and Z = 2. The strongest reflections in the X-ray powder pattern [(d, Å (I)(hkl)] are: 9.62(100)(010,100); 5.551(50)(110); 4.616(37)(012,102); 3.823(64)(112); 3.436(25)(211), 2.742(38)(032,302), 2.528(37)(123,213), 2.180(35)(042,402;223). In both hielscherite and sulfite-rich thaumasite, pyramidal sulfite groups occupy the same site as trigonal carbonate groups, with analogous O sites, whereas tetrahedral sulfate groups occupy separate positions. Hielscherite is named in honour of the German mineral collector Klaus Hielscher (b. 1957). © 2012 Mineralogical Society. Source

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