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Chukanov N.V.,RAS Institute of Problems of Chemical Physics | Rastsvetaeva R.K.,Russian Academy of Sciences | Aksenov S.M.,Russian Academy of Sciences | Pekov I.V.,Moscow State University | And 5 more authors.
Geology of Ore Deposits | Year: 2012

A new mineral, günterblassite, has been found in the basaltic quarry at Mount Rother Kopf near Gerolstein, Rheinland-Pfalz, Germany as a constituent of the late assemblage of nepheline, leucite, augite, phlogopite, åkermanite, magnetite, perovskite, a lamprophyllite-group mineral, götzenite, chabazite-K, chabazite-Ca, phillipsite-K, and calcite. Günterblassite occurs as colorless lamellar crystals up to 0. 2 × 1 × 1. 5 mm in size and their clusters. The mineral is brittle, with perfect cleavage parallel to (001) and less perfect cleavage parallel to (100) and (010). The Mohs hardness is 4. The calculated and measured density is 2. 17 and 2. 18(1) g/cm3, respectively. The IR spectrum is given. The new mineral is optically biaxial and positive as follows: α = 1. 488(2), β = 1. 490(2), γ = 1. 493(2), 2Vmeas = 80(5)°. The chemical composition (electron microprobe, average of seven point analyses, H2O is determined by gas chromatography, wt %) is as follows: 0. 40 Na2O, 5. 18 K2O, 0. 58 MgO, 3. 58 CaO, 4. 08 BaO, 3. 06 FeO, 13. 98 Al2O3, 52. 94 SiO2, 15. 2 H2O, and the total is 98. 99. The empirical formula is Na0. 15K1. 24Ba0. 30Ca0. 72Mg0. 16F0. 48 2+[Si9. 91Al3. 09O25. 25(OH)3. 75] · 7. 29H2O. The crystal structure has been determined from a single crystal, R = 0. 049. Günterblassite is orthorhombic, space group Pnm21; the unit-cell dimensions are a = 6. 528(1), b = 6. 970(1), c = 37. 216(5) Å, V = 1693. 3(4) Å3, Z = 2. Günterblassite is a member of a new structural type; its structure is based on three-layer block [Si13O25(OH,O)4]. The strong reflections in the X-ray powder diffraction pattern [d Å (I, %) are as follows: 6. 532 (100), 6. 263 (67), 3. 244 (49), 3. 062 (91), 2. 996 (66), 2. 955 (63), and 2. 763 (60). The mineral was named in honor of Günter Blass (born in 1943), a well-known amateur mineralogist and specialist in electron microprobe and X-ray diffraction. The type specimen of günterblassite is deposited in the collections of the Fersman Mineralogical Museum of the Russian Academy of Sciences, Moscow, Russia, with the registration number 4107/1. © 2012 Pleiades Publishing, Ltd.


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.


Chukanov N.V.,RAS Institute of Problems of Chemical Physics | Zubkova N.V.,Moscow State University | Pekov I.V.,Moscow State University | Belakovskiy D.I.,Russian Academy of Sciences | And 4 more authors.
Geology of Ore Deposits | Year: 2013

A new mineral, hillesheimite, has been found in the Graulai basaltic quarry, near the town of Hillesheim, the Eifel Mountains, Rhineland-Palatinate (Rheinland-Pfalz), Germany. It occurs in the late assemblage comprising nepheline, augite, fluorapatite, magnetite, perovskite, priderite, götzenite, lamprophyllite-group minerals, and åkermanite. Colorless flattened crystals of hillesheimite reaching 0.2 × 1 × 1.5 mm in size and aggregates of the crystals occur in miarolitic cavities in alkali basalt. The mineral is brittle, with Mohs' hard-ness 4. Cleavage is perfect parallel to (010) and distinct on (100) and (001). D calc = 2.174 g/cm3, D meas = 2.16(1) g/cm3. IR spectrum is given. Hillesheimite is biaxial (-), α = 1.496(2), β = 1.498(2), γ = 1.499(2), 2V meas = 80°. The chemical composition (electron microprobe, mean of 4 point analyses, H2O determined from structural data, wt %) is as follows: 0.24 Na2O, 4.15 K2O, 2.14 MgO, 2.90 CaO, 2.20 BaO, 2.41 FeO, 15.54 Al2O3, 52.94 SiO2, 19.14 H2O, total is 101.65. The empirical formula is: K0.96Na0.08Ba0.16Ca0.56Mg0.58Fe 0.37 2+ [Si9.62Al3.32O23(OH)6][(OH)0.82(H2O)0.18] · 8H2O. The crystal structure has been determined from X-ray single-crystal diffraction data, R = 0.1735. Hillesheimite is orthorhombic, space group Pmmn, the unit-cell dimensions are: a = 6.979(11), b = 37.1815(18), c = 6.5296(15) Å; V=1694(3) Å3, Z = 2. The crystal structure is based on the block [(Si,Al)13O25(OH)4] consisting of three single tetrahedral layers linked via common vertices and is topologically identical to the triple layers in günterblassite and umbrianite. The strong reflections [d Å (I %)] in the X-ray powder diffraction pattern are: 6.857(58), 6.545(100), 6.284(53), 4.787(96), 4.499(59), 3.065(86), 2.958(62), 2.767(62). The mineral was named after its type locality. Type specimens are deposited in the Fersman Mineralogical Museum, Russian Academy of Sciences, Moscow, registration number 4174/1. © 2013 Pleiades Publishing, Ltd.


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.


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.


Pekov I.V.,Moscow State University | Siidra O.I.,Saint Petersburg State University | Chukanov N.V.,RAS Institute of Problems of Chemical Physics | Yapaskurt V.O.,Moscow State University | And 4 more authors.
Mineralogy and Petrology | Year: 2015

A new mineral engelhauptite, KCu3(V2O7)(OH)2Cl, was found within cavities in nepheline basalts at the Auf’m Kopp quarry (“Schlackenkegel der Höhe 636 südöstlich Neroth”), Daun, Eifel region, Rheinland-Pfalz, Germany. Associated minerals are volborthite, allophane, malachite, tangeite and chrysocolla; earlier minerals belonging to the primary, high-temperature parageneses are augite, mica of the phlogopite–oxyphlogopite series, sanidine, nepheline, leucite, fluorapatite and magnetite. Engelhauptite occurs as spherulites (up to 0.2 mm in diameter) and bunches consisting of rough spindle-shaped crystals elongated parallel to [0001]. The crystals are up to 0.12 mm long and up to 0.04 mm thick. Individual grains of engelhauptite are transparent, whereas their aggregates are translucent. The mineral is yellow-brown to brown, typically with an olive green hue. The luster is vitreous. Engelhauptite is brittle, cleavage is not observed, fracture is uneven. Dcalc = 3.86 g cm−3. Engelhauptite is optically uniaxial (+), ω = 1.978(4), ε = 2.021(4). Chemical data (wt.%, electron-microprobe, H2O by difference) are as following: K2O 9.63, FeO 0.05, NiO 0.29, CuO 46.11, Al2O3 0.24, V2O5 34.92, SO3 0.79, Cl 5.94, H2Ocalc 3.37, O = Cl2 -1.34, total 100.00. The empirical formula, based on 10 (O + OH + Cl) apfu, is K1.05(Cu2.97Al0.02Ni0.02)Σ3.01(V1.97S0.05)Σ2.02O7.23(OH)1.91Cl0.86. Engelhauptite is hexagonal, P63/mmc, a = 5.922(2), c = 14.513(5) Å, V = 440.78(3) Å3 and Z = 2. The eight strongest reflections of the powder X-ray diffraction pattern [d,Å(I) (hkl)] are: 7.32(98) (002), 4.224(17) (102), 2.979(100) (104, 110), 2.759(19) (112), 2.565(18) (200), 2.424(18) (202), 1.765(16) (206) and 1.481(14) (208, 220). The crystal structure of engelhauptite has been solved from the single-crystal X-ray diffraction data and refined to R = 0.090 on the basis of 135 unique observed reflections. The structure is based upon the [Cu2+ 3(V2O7)(OH)2]0 framework formed by the linkage of deficient brucite-like layers of Jahn-Teller distorted Cuφ6 octahedra (φ = O, OH) via divanadate V2O7 groups. The framework contains large channels occupied by K+ cations and Cl− anions. Engelhauptite is closely related to volborthite, Cu3(V2O7) (OH)2∙2H2O, and can be considered as its analogue resulting from the replacement of H2O molecules by the equal amounts of K+ and Cl− ions. The mineral is named in honour of the German amateur mineralogist and mineral collector Bernd Engelhaupt (born 1946). © 2015, Springer-Verlag Wien.


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.


Pekov I.V.,Moscow State University | Siidra O.I.,Saint Petersburg State University | Chukanov N.V.,RAS Institute of Problems of Chemical Physics | Yapaskurt V.O.,Moscow State University | And 4 more authors.
Mineralogy and Petrology | Year: 2015

A new mineral engelhauptite, KCu3(V2O7)(OH)2Cl, was found within cavities in nepheline basalts at the Auf’m Kopp quarry (“Schlackenkegel der Höhe 636 südöstlich Neroth”), Daun, Eifel region, Rheinland-Pfalz, Germany. Associated minerals are volborthite, allophane, malachite, tangeite and chrysocolla; earlier minerals belonging to the primary, high-temperature parageneses are augite, mica of the phlogopite–oxyphlogopite series, sanidine, nepheline, leucite, fluorapatite and magnetite. Engelhauptite occurs as spherulites (up to 0.2 mm in diameter) and bunches consisting of rough spindle-shaped crystals elongated parallel to [0001]. The crystals are up to 0.12 mm long and up to 0.04 mm thick. Individual grains of engelhauptite are transparent, whereas their aggregates are translucent. The mineral is yellow-brown to brown, typically with an olive green hue. The luster is vitreous. Engelhauptite is brittle, cleavage is not observed, fracture is uneven. Dcalc = 3.86 g cm−3. Engelhauptite is optically uniaxial (+), ω = 1.978(4), ε = 2.021(4). Chemical data (wt.%, electron-microprobe, H2O by difference) are as following: K2O 9.63, FeO 0.05, NiO 0.29, CuO 46.11, Al2O3 0.24, V2O5 34.92, SO3 0.79, Cl 5.94, H2Ocalc 3.37, O = Cl2 -1.34, total 100.00. The empirical formula, based on 10 (O + OH + Cl) apfu, is K1.05(Cu2.97Al0.02Ni0.02)Σ3.01(V1.97S0.05)Σ2.02O7.23(OH)1.91Cl0.86. Engelhauptite is hexagonal, P63/mmc, a = 5.922(2), c = 14.513(5) Å, V = 440.78(3) Å3 and Z = 2. The eight strongest reflections of the powder X-ray diffraction pattern [d,Å(I) (hkl)] are: 7.32(98) (002), 4.224(17) (102), 2.979(100) (104, 110), 2.759(19) (112), 2.565(18) (200), 2.424(18) (202), 1.765(16) (206) and 1.481(14) (208, 220). The crystal structure of engelhauptite has been solved from the single-crystal X-ray diffraction data and refined to R = 0.090 on the basis of 135 unique observed reflections. The structure is based upon the [Cu2+3(V2O7)(OH)2]0 framework formed by the linkage of deficient brucite-like layers of Jahn-Teller distorted Cuφ6 octahedra (φ = O, OH) via divanadate V2O7 groups. The framework contains large channels occupied by K+ cations and Cl− anions. Engelhauptite is closely related to volborthite, Cu3(V2O7) (OH)2∙2H2O, and can be considered as its analogue resulting from the replacement of H2O molecules by the equal amounts of K+ and Cl− ions. The mineral is named in honour of the German amateur mineralogist and mineral collector Bernd Engelhaupt (born 1946). © 2015 Springer-Verlag Wien


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.


Zubkova N.V.,Moscow State University | Chukanov N.V.,RAS Institute of Problems of Chemical Physics | Pekov I.V.,Moscow State University | Turchkova A.G.,Moscow State University | And 4 more authors.
Mineralogy and Petrology | Year: 2016

A Ba-dominant (Ba > K) analogue of hydrodelhayelite (BDAH) from Löhley (Eifel Mts., Rhineland-Palatinate, Germany) and Ba-enriched varieties of related double- and triple-layer phyllosilicates from Eifel are studied. The crystal structure of BDAH was solved by direct methods and refined to R = 0.0698 [1483 unique reflections with I > 2σ(I)]. It is orthorhombic, Pmmn, a = 23.9532(9), b = 7.0522(3), c = 6.6064(3) Å, V = 1115.97(8) Å3, Z = 2. The structure is based upon delhayelite-type double-layer tetrahedral blocks [(Al,Si)4Si12O34(OH,O)4] connected by chains of (Ca,Fe)-centered octahedra. Ba2+ and subordinate K+ occur at partially vacant sites in zeolitic channels within the tetrahedral blocks. The crystal-chemical formula of BDAH is: (Ba0.42K0.34□0.24)(Ca0.88Fe0.12)2(□0.90Mg0.10)2[Si6(Al0.5Si0.5)2O17(OH0.71O0.29)2]⋅6H2O. The formation of BDAH and Ba-rich varieties of altered delhayelite/fivegite, günterblassite and hillesheimite is considered as a result of leaching of Na, Cl, F and, partially, K and Ca accompanied with hydration and the capture of Ba as a result of natural ion exchange. These minerals are structurally a “bridge” between single-layer phyllosilicates and zeolites having the open three-dimensional tetrahedral Al-Si-O frameworks. © 2016 Springer-Verlag Wien

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