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1.
N. V. Chukanov S. M. Aksenov R. K. Rastsvetaeva K. V. Van D. I. Belakovskiy I. V. Pekov V. V. Gurzhiy W. Schüller B. Ternes 《Geology of Ore Deposits》2015,57(8):721-731
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). D calc = 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), 2V meas = 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 \(P\bar 1\); 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), (\(01\bar 2\), \(1\bar 20\)), 2.885 (100) (221, \(2\bar 11\), \(1\bar 21\)), 2.691 (21) (222, \(2\bar 10\)), 2.397 (21) (\(02\bar 2\), \(21\bar 1\), 203, 031), 1.774 (37) (412, \(3\bar 21\)). The type specimen is deposited in the Fersman Mineralogical Museum, Russian Academy of Sciences, Moscow, registration number 4420/1. 相似文献
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Summary Batiferrite, ideally Ba[Ti2Fe10]O19, was found in the Quaternary volcanic rocks near üdersdorf, Graulai, and Altburg, western Eifel area, Germany. The new mineral
typically occurs as euhedral platy grains in cavities of melilite- and leucite-nephelinite basalts. Associated minerals are
hematite, magnetite, titanite, g?tzenite, clinopyroxene, nepheline, and biotite. It exhibits a hexagonal tabular habit flattened
on {0001}, diameter 0.5–1 mm, thickness 20–125 μm, and {10&1macr;3}, {10&1macr;0} as observable forms. The mineral is opaque, of black
color with submetallic lustre, and shows a ferrimagnetic behavior. VHN50 is 793 with a range of 710–841 from ten indentations. The quantitative reflectance measurements of Ro/Re on oriented grains in air and oil immersion, respectively, are [%]: for 470 nm 22.1/20.1 and 8.4/7.1, for 546 nm 21.0/19.4
and 7.8/6.6, for 589 nm 20.2/18.8 and 7.4/6.3, and for 650 nm 19.3/18.3 and 6.8/5.9. The bireflectance is distinct (air) to
weak (oil), and parallel (0001) a moderate anisotropy with straight extinction can be observed. Typical microprobe analyses
give [wt%] K2O 0.28–0.33, Na2O 0.17–0.20, SrO 0.46–0.55, BaO 11.80–12.17, MgO 1.27–1.47, Al2O3 0.31–0.33, TiO2 13.11–13.63, MnO 2.38–2.57, Fe2O3 61.36–63.12, FeO 5.49–5.86 (Fe3+/Fe2+ calculated for charge compensation), which is equivalent to (Ba0.84Na0.06K0.06Sr0.05)1.01(Fe8.48
3+Fe0.86
2+Ti1.82Mg0.37Mn0.37Al0.06)11.96O19 as the average composition based on 19 oxygen atoms. Batiferrite is a magnetoplumbite-type mineral with hexagonal symmetry,
space group P6
3
/mmc (no. 194), a = 5.909(1) ?, c = 23.369(4) ?, V = 706.6(2) ?3, Z = 2, and a calculated density of 5.016 gcm−3. The structure was refined to R1 = 0.031 for 278 unique reflections with Fo
2 > 4σ (Fo
2) and R1 = 0.079 for all 452 unique observations using single crystal X-ray data. The strongest reflections of the X-ray powder diffraction
pattern are [d
obs, I/Io, (hkl)]: 2.631, 100, (114); 2.799, 80, (107); 1.478, 70, (220); 2.429, 60, (203); 1.672, 50, (217). The new mineral is comparable to the other Ba containing magnetoplumbite-type minerals haggertyite and
hawthorneite, the iron content, however, is much higher and in the range of magnetoplumbite. The large cation site (A) is
dominated by Ba, and four of the five remaining crystallographic cation sites in the structure are dominated by Fe (M1, 2,
3, 5), the octahedrally coordinated M4-site is dominated by Ti. No oxygen vacancy on the O3-site like in plumboferrite can
be observed. Batiferrite is named for its main chemical composition and the relationship to the M-type hexaferrites (polytype
5H).
Received December 14, 1999; accepted March 2, 2000 相似文献
Zusammenfassung Batiferrit, ein neues ferrimagnetisches Mineral des Magnetoplumbit-Typs aus den quart?ren Vulkaniten der West-Eifel, Deutschland Das neue Mineral Batiferrite, mit der Idealformel Ba[Ti2Fe10]O19, wurde an drei Fundpunkten in den Quart?ren Vulkangesteinen der westlichen Eifel, Deutschland, in der N?he von üdersdorf, Graulai und Altburg gefunden. Das neue Mineral tritt typischerweise bl?ttchenf?rmig in kleinen Hohlr?umen von Melilith- und Leucit-Nephelininit Basalten auf. Vergesellschaftete Minerale sind H?matit, Magnetit, Titanit, G?tzenit, Klinopyroxen, Nephelin und Biotit. Der Habitus ist hexagonal tafelig nach {0001}, mit einem Durchmesser von 0.5–1 mm und einer Dicke von 20–125 μm, zus?tzlich k?nnen die Formen {10&1macr;3} und {10&1macr;0} beobachtet werden. Das Mineral ist opak, hat eine schwarze Farbe mit einem leicht metallischen Glanz, und ist ferromagnetisch. Die H?rte VHN50 ist 793 mit einem Bereich von 710–841 aus 10 Eindruckbestimmungen. Die quantitativen Reflexionsmessungen von Ro/Re an orientierten K?rnern in Luft beziehungsweise ?limmersion, ergaben [%]: für 470 nm 22.1/20.1 und 8.4/7.1, für 546 nm 21.0/19.4 und 7.8/6.6, für 589 nm 20.2/18.8 und 7.4/6.3, und für 650 nm 19.3/18.3 und 6.8/5.9. Die Bireflexion ist deutlich (Luft) bis schwach (?l) und parallel (0001) kann eine mittlere Anisotropie mit gerader Ausl?schung beobachtet werden. Eine typische Mikrosondenanalyse ergibt [wt%] K2O 0.28–0.33, Na2O 0.17–0.20, SrO 0.46–0.55, BaO 11.80–12.17, MgO 1.27–1.47, Al2O3 0.31–0.33, TiO2 13.11–13.63, MnO 2.38–2.57, Fe2O3 61.36–63.12, FeO 5.49–5.86 (Fe3+/Fe2+ berechnet zum Ladungsausgleich), die mittlere chemische Formel auf der Basis von 19 Sauerstoffatomen lautet (Ba0.84Na0.06K0.06Sr0.05)1.01 (Fe8.48 3+Fe0.86 2+Ti1.82Mg0.37Mn0.37Al0.06)11.96O 19. Batiferrit ist ein Mineral der Magnetoplumbitgruppe, hat hexagonale Symmetrie mit der Raumgruppe P63/mmc (Nr. 194), a = 5.909(1) ?, c = 23.369(4) ?, V = 706.6(2) ?3, Z = 2, und einer berechneten Dichte von 5.016 gcm−3. Die Struktur wurde aus Einkristall-R?ntgendaten bis zu einem R1-Wert von 0.031 für 278 Fo 2 > 4σ(Fo 2), und einem R1-Wert von 0.079 für alle 452 Fo 2 verfeinert. Die st?rksten Beugungsreflexe der Pulver-R?ntgendaten sind [dobs, I/Io, (hkl)]: 2.631, 100, (114); 2.799, 80, (107); 1.478, 70, (220); 2.429, 60, (203); 1.672, 50, (217). Das neue Mineral weist deutliche ?hnlichkeiten zu den anderen beiden Ba-reichen Mineralen Haggertyit und Hawthorneit der Magnetoplumbit-Gruppe auf, jedoch ist der Eisengehalt wesentlich h?her und im Bereich des Minerals Magnetoplumbit. Der gro?e Kationenplatz (A) ist von Barium dominiert, vier (M1, 2, 3, 5) der restlichen fünf kristallographischen Kationenpl?tze in der Struktur sind fast ausschlie?lich mit Fe, die oktaedrisch koordinierte M4-Position ist überwiegend mit Ti besetzt. An der O3-Position konnte kein Sauerstoffdefizit wie in Plumboferrit festgestellt werden. Batiferrit ist nach seiner chemischen Beschaffenheit und nach seiner Zugeh?hrigkeit zu den M-Typ Hexaferriten (Polytyp 5H) benannt.
Received December 14, 1999; accepted March 2, 2000 相似文献
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N. V. Chukanov G. Blass I. V. Pekov D. I. Belakovskiy K. V. Van R. K. Rastsvetaeva S. M. Aksenov 《Geology of Ore Deposits》2012,54(8):647-655
Non-metamict perrierite-(La) discovered in the Dellen pumice quarry, near Mendig, in the Eifel volcanic district, Rheinland-Pfalz, Germany has been approved as a new mineral species (IMA no. 2010-089). The mineral was found in the late assemblage of sanidine, phlogopite, pyrophanite, zirconolite, members of the jacobsite-magnetite series, fluorcalciopyrochlore, and zircon. Perrierite-(La) occurs as isolated prismatic crystals up to 0.5 × 1 mm in size within cavities in sanidinite. The new mineral is black with brown streak; it is brittle, with the Mohs hardness of 6 and distinct cleavage parallel to (001). The calculated density is 4.791 g/cm3. The IR spectrum does not contain absorption bands that correspond to H2O and OH groups. Perrierite-(La) is biaxial (-), α = 1.94(1), β = 2.020(15), γ = 2.040(15), 2V meas = 50(10)°, 2V calc = 51°. The chemical composition (electron microprobe, average of seven point analyses, the Fe2+/Fe3+ ratio determined from the X-ray structural data, wt %) is as follows: 3.26 CaO, 22.92 La2O3, 19.64 Ce2O3, 0.83 Pr2O2, 2.09 Nd2O3, 0.25 MgO, 2.25 MnO, 3.16 FeO, 5.28 Fe2O3, 2.59 Al2O3, 16.13 TiO2, 0.75 Nb2O5, and 20.06 SiO2, total is 99.21. The empirical formula is (La1.70Ce1.45Nd0.15Pr0.06Ca0.70)Σ4.06(Fe 0.53 2+ Mn0.38Mg0.08)Σ0.99(Ti2.44Fe 0.80 3+ Al0.62Nb0.07)Σ3.93Si4.04O22. The simplified formula is (La,Ce,Ca)4(Fe2+,Mn)(Ti,Fe3+,Al)4(Si2O7)2O8. The crystal structure was determined by a single crystal. Perrierite-(La) is monoclinic, space group P21/a, and the unit-cell dimensions are as follows: a =13.668(1), b = 5.6601(6), c = 11.743(1) Å, β = 113.64(1)°; V = 832.2(2) Å3, Z = 2. The strong reflections in the X-ray powder diffraction pattern are [d, Å (I, %) (hkl)]: 5.19 (40) (110), 3.53 (40) ( $\overline 3 $ 11), 2.96 (100) ( $\overline 3 $ 13, 311), 2.80 (50) (020), 2.14 (50) ( $\overline 4 $ 22, $\overline 3 $ 15, 313), 1.947 (50) (024, 223), 1.657 (40) ( $\overline 4 $ 07, $\overline 4 $ 33, 331). The holotype specimen of perrierite-(La) is deposited at the Fersman Mineralogical Museum, Russian Academy of Sciences, Moscow, Russia, with the registration number 4059/1. 相似文献
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Summary The new mineral ternesite, Ca5(SiO4)2SO4, has been found at the Ettringer Bellerberg near Mayen, Eifel, Germany. The crystal structure, already known from the synthetic analogue, was refined from single crystal X-ray data: orthorhombic, space group Puma with a= 6.863(1)Å, b=15.387(2) Å, c=10.181(1) Å Z=4, R=0.058, Rw=0.046 for 820 unique reflections with F0> 3(F0) and 96 variable parameters. The strongest peaks in the powder pattern are (d-value (Å),I, hkl): 2.830, 100, (033)/2.853, 63, (230)/2.565, 55, (060)/3.198, 42, (132)/1.892, 39, (035) + (125). The mineral is optically biaxial negative with refractive indices nx = 1.630(1) (parallel [100]), ny = 1.637(2) (parallel [001]), and nz = 1.640(1) (parallel [010]). The optical angle 2Vx was measured as 63.5(5)°.
With 1 figure 相似文献
Ternesit, Ca5(SiO4)2SO4, ein neues Mineral vom Ettringer Bellerberg, Eifel, Deutschland
Zusammenfassung Das neue Mineral Ternesit, Ca5(SiO4)2SO4, wurde am Ettringer Bellerberg bei Mayen, Eifel, Deutschland gefunden. Die schon vom synthetischen Analogen her bekannte Kristallstruktur wurde aus Einkristalldaten von natürlichem Material verfeinert: Das Mineral ist orthorhombisch, Raumgruppe Pnma mit a= 6.863(1)Å, b=15.387(2) Å, c=10.181(1) Å, Z=4, R=0.058, Rw=0.046 für 820 unabhängige Reflexe mit F0> 3(F0) und 96 variablen Parametern. Die stärksten Maxima im Pulverbeugungsdiagramm sind (d-Wert (Å),I, hkl): 2.830, 100, (033)/2.853, 63, (230)/2.565, 55, (060)/ 3.198, 42, (132)/1.892, 39, (035) + (125). Das Mineral ist optisch zweiachsig negativ mit Brechungsindizes nx = 1.630(1) (parallel [100]), ny = 1.637 (2) (parallel [001]), und nz = 1.640(1) (parallel [010]). Der optische Achsenwinkel 2Vx wurde zu 63.5(5)° gemessen.
With 1 figure 相似文献
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M. Auernhammer H. Effenberger G. Hentschel Th. Reinecke E. Tillmanns 《Mineralogy and Petrology》1993,48(2-4):153-166
Summary Nickenichite is a new mineral found close to the village of Nickenich at the Nickenicher Sattel, Eifel, Germany. The chemical composition is NaxCayCuz(Mg, Fe, Al)3(AsO4)3, x 0.8, y 0.4, 0.4 and was derived by means of electron microprobe analyses and by a crystal structure investigation. The latter was determined from single-crystal X-ray data:a = 11.882(4)Å,b = 12.760(4)Å,c = 6.647(2)Å, = 112.81(2)°, space group C2/c,Z = 4;R = 0.053 andR
w
= 0.033 from 984 observed data and 102 free variables. Nickenichite is structurally related to the minerals o'danielite and johillerite. The two crystallographically different octahedrally coordinated cation positionsMe = (Mg, Fe, Al) have averageMe-O distances of 2.108 Å and 2.056 Å, octahedra share edges to form zig-zag chains in
; the chains are interconnected by AsO4 tetrahedra. In addition the compound is characterized by partially occupied Na[4+4], Ca[6+2] and Cu[4] positions.
With 2 Figures 相似文献
Nickenichit, ein neues Arsenat aus der Eifel, Deutschland
Zusammenfassung Nickenichit ist ein neues Mineral, das nahe dem Ort Nickenich, am Nickenicher Sattel, Eifel, Deutschland, gefunden wurde. Die chemische Formel ist NaxCayCuz, (Mg, Fe, Al)3(AsO4)3, x 0,8, y 0,4, z 0,4 und wurde mittels Elektronenstrahl-Mikrosondenanalysen und einer Kristallstrukturuntersuchung ermittelt. Letztere wurde mit Einkristall-Röntgendaten durchgeführt:a = 11,882(4) Å,b = 12,760(4) Å,c = 6,647(2) Å, = 112,81(2)°, Raumgruppe C2/c,Z = 4;R = 0,053 undR w = 0,033 für 984 beobachtete Daten und 102 freie Variable. Nickenichit zeigt enge strukturelle Beziehungen zu den Mineralen O'Danielit und Johillerit. Die zwei kristallographisch verschiedenen oktaedrisch koordinierten KationpositionenMe = (Mg, Fe, Al) haben mittlereMe-O-Abstände von 2,108 Å und 2,056 Å, die Oktaeder werden über Kanten zu zick-zack-artigen Ketten in verknüpft, diese werden untereinander über AsO4-Tetraeder vernetzt. Des weiteren ist die Verbindung durch partiell besetzte Na[4+4]-, Ca[6+2]- und Cu[4]-Positionen charakterisiert.
With 2 Figures 相似文献
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ABSTRACT Maar craters often contain exceptionally preserved fossils and maar sediments may reflect detailed environmental changes. Volcanosedimentary processes in a Middle Eocene maar crater lake are illustrated by the deposits of Eckfeld Maar in the Tertiary Hocheifel Volcanic Field (Rhenish Massif, Germany). The maar origin of the basin is evident from a circular negative gravity anomaly which indicates a low-density funnel-shaped basin filling. From the facies analysis of an Eocene (Eckfeld) and a Pleistocene (Döttingen) maar we develop a lithozone classification for the interpretation of maar sediments: syn-/post-eruptive breccias are followed by a fining-upwards sequence of lacustrine mud with coarse layers and final swamp deposits. From the facies analysis and regional geological data we reconstruct the pre- to post-eruptive history of a maar crater prior to post-Eocene uplift. These observations can be used for the interpretation of Tertiary and Quaternary maar craters that are ideal fossil and sediment traps. 相似文献
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Gerhard Hentschel Kurt Abraham Werner Schreyer 《Contributions to Mineralogy and Petrology》1980,73(2):127-130
Idiomorphic crystals of roedderite occur in melt-coated cavities of xenoliths of contact-altered quartz-sillimanite and quartz-feldspar gneisses which were ejected with the tephritic lava of the Bellerberg volcano. Physical and chemical properties of three different sets of crystals agree generally with those of roedderites from meteorites, in which so far the mineral had been found exclusively. In detail, however, there are characteristic chemical differences amongst the Eifel roedderites with one set of crystals matching closely the ideal formula (Na,K)2Mg5 Si12O30, a second set containing excess alkalies according to the substitution Na+0.5 Mg2+, and a third set richer in iron having an alkali deficiency following Fe3+Fe2++Na+.The terrestrial roedderites are considered to be precipitates from highly alkaline, MgSi-rich, but Aldeficient gas phases that evolved through contact heating of the gneisses by the tephrite magma. 相似文献
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A. E. Zadov V. M. Gazeev O. V. Karimova N. N. Pertsev I. V. Pekov E. V. Galuskin I. O. Galuskina A. G. Gurbanov D. I. Belakovsky S. E. Borisovsky P. M. Kartashov A. G. Ivanova O. V. Yakubovich 《Geology of Ore Deposits》2011,53(8):775-782
A new mineral of the neptunite group, magnesioneptunite KNa2Li(Mg,Fe)2Ti2Si8O24, a Mg-dominant analogue of neptunite and manganoneptunite, has been found in the Upper Chegem caldera near Mount Lakargi, Kabardino-Balkaria, the North Caucasus, Russia in a xenolith of altered sandstone located between skarnified carbonate xenoliths and ignimbrite. Magnesioneptunite occurs as nearly isometric grains and aggregates up to 0.1 mm in size in the cores of some grains of a Mg-rich variety of neptunite with Mg/(Fe + Mn) = 0.7?1.0. The chemical composition of magnesioneptunite with a maximum Mg content is as follows, wt %: 3.63 K2O, 8.21 Na2O, 1.73 Li2O, 6.47 MgO, 0.04 MnO, 5.87 FeO, 0.07 Al2O3, 18.73 TiO2, 56.88 SiO2, 99.62 in total. The empirical formula is (K0.67Na0.32Ca0.01)Σ1.00Na2.06Li1.00 · (Mg1.39Fe 0.71 2+ )Σ2.10(Si7.90Al0.01)Σ7.91O24. Grains of magnesioneptunite are dark brown to red-brown, translucent, with vitreous luster. D calc = 3.15 g/cm3, and the Mohs hardness is 5–6. Cleavage parallel to the (110) is perfect. The new mineral is optically biaxial, positive, α = 1.697(2), β = 1.708 (3), γ = 1.725(3), 2V meas = 45(15)°. The mineral is associated with quartz, alkali feldspar, rutile, aegirine, and neptunite. Magnesioneptunite and the Mg-rich variety of neptunite were formed as products of ilmenite alteration. Magnesioneptunite is monoclinic, C2/c; unit-cell parameters: a = 16.327(7), b = 12.4788(4), c = 9.9666(4) Å, β = 115.6519(5)°, V = 1830.5(1) Å3, Z = 4. The type specimen is deposited at the Fersman Mineralogical Museum of the Russian Academy of Sciences, Moscow. 相似文献
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Bulk and slab geometry optimizations and calculations of the electrostatic potential at the surface of both pyrophyllite [Al2Si4O10(OH)2] and talc [Mg3Si4O10(OH)2] were performed at Hartree–Fock and DFT level. In both pyrophyllite and talc cases, a modest (001) surface relaxation was observed, and the surface preserves the structural features of the crystal: in the case of pyrophyllite the tetrahedral and octahedral sheets are strongly distorted with respect to the ideal hexagonal symmetry (and basal oxygen are located at different heights along the direction normal to the basal plane), whereas the structure of talc deviates slightly from the ideal hexagonal symmetry (almost co-planar basal oxygen). The calculated distortions are fully consistent with those experimentally observed. Although the potentials at the surface of pyrophyllite and talc are of the same order of magnitude, large topological differences were observed, which could possibly be ascribed to the differences between the surface structures of the two minerals. Negative values of the potential are located above the basal oxygen and at the center of the tetrahedral ring; above silicon the potential is always positive. The value of the potential minimum above the center of the tetrahedral ring of pyrophyllite is ?0.05 V (at 2 Å from the surface), whereas in the case of talc the minimum is ?0.01 V, at 2.7 Å. In the case of pyrophyllite the minimum of potential above the higher basal oxygen is located at 1.1 Å and it has a value of ?1.25 V, whereas above the lower oxygen the value of the potential at the minimum is ?0.2 V, at 1.25 Å; the talc exhibits a minimum of ?0.75 V at 1.2 Å, above the basal oxygen. 相似文献
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S. N. Britvin N. V. Chukanov G. K. Bekenova M. A. Yagovkina A. V. Antonov A. N. Bogdanova N. I. Krasnova 《Geology of Ore Deposits》2008,50(7):556-564
Karchevskyite, a new mineral related to the family of layered double hydroxides (LDHs), has been found in the Iron open pit at the Kovdor carbonatite massif, Kola Peninsula, Russia. The mineral occurs as spherulites of up to 1.5 mm in diameter composed of thin, curved lamellae. Dolomite, magnetite, quintinite-3T, strontium carbonate, and fluorapatite are associated minerals. Karchevskyite is white in aggregates and colorless in separate platelets. Its luster is vitreous with a pearly shine on the cleavage surface. The new mineral is nonfluorescent. The Mohs hardness is 2. The cleavage is eminent (micalike), parallel to {001}. The measured density is 2.21(2) g/cm3, and the calculated value is 2.18(1) g/cm3. Karchevskyite is colorless and nonpleochroic in immersion liquids. It is uniaxial, negative, ω = 1.542(2), and ? = 1.534(2). The chemical composition (electron microprobe, average of ten point analyses, standard deviation in parentheses, wt %) is as follows: 29.7(1.1) MgO, 18.3(0.7) Al2O3, 7.4(0.4) SrO, 0.2(0.1) CaO, 1.3(0.2) P2O5, 14.5(0.4) CO2, and 28.6 H2O (estimated by difference); the total is 100. The empirical formula calculated on the basis of nine Al atoms is Mg18.00Al9.00(OH)54.00(Sr1.79Mg0.48Ca0.09)2.36 (Ca3)8.26(PO4)0.46(H2O)6.54(H3O)4.18. The idealized formula is [Mg18Al9(OH)54][Sr2(CO3, PO4)9(H2O, H3O)11]. The new mineral slowly dissolves in 10% HCl with weak effervescence. Karchevskyite is trigonal; possible space groups are P3, P3, P $ \overline 3 Karchevskyite, a new mineral related to the family of layered double hydroxides (LDHs), has been found in the Iron open pit
at the Kovdor carbonatite massif, Kola Peninsula, Russia. The mineral occurs as spherulites of up to 1.5 mm in diameter composed
of thin, curved lamellae. Dolomite, magnetite, quintinite-3T, strontium carbonate, and fluorapatite are associated minerals. Karchevskyite is white in aggregates and colorless in separate
platelets. Its luster is vitreous with a pearly shine on the cleavage surface. The new mineral is nonfluorescent. The Mohs
hardness is 2. The cleavage is eminent (micalike), parallel to {001}. The measured density is 2.21(2) g/cm3, and the calculated value is 2.18(1) g/cm3. Karchevskyite is colorless and nonpleochroic in immersion liquids. It is uniaxial, negative, ω = 1.542(2), and ɛ = 1.534(2).
The chemical composition (electron microprobe, average of ten point analyses, standard deviation in parentheses, wt %) is
as follows: 29.7(1.1) MgO, 18.3(0.7) Al2O3, 7.4(0.4) SrO, 0.2(0.1) CaO, 1.3(0.2) P2O5, 14.5(0.4) CO2, and 28.6 H2O (estimated by difference); the total is 100. The empirical formula calculated on the basis of nine Al atoms is Mg18.00Al9.00(OH)54.00(Sr1.79Mg0.48Ca0.09)2.36 (Ca3)8.26(PO4)0.46(H2O)6.54(H3O)4.18. The idealized formula is [Mg18Al9(OH)54][Sr2(CO3, PO4)9(H2O, H3O)11]. The new mineral slowly dissolves in 10% HCl with weak effervescence. Karchevskyite is trigonal; possible space groups are
P3, P3, P
1m, P31m, P312, P312, P3m1, or P3m1; unit-cell dimensions are a = 16.055(6), c = 25.66(1) ?, V = 5728(7) ?3, Z = 3. The strongest reflections in the X-ray powder diffraction pattern [d, (I, %)(hkl)] are: 8.52(10)(003), 6.41(4)(004), 5.13(3)(005), 4.27(6)(006), 3.665(9)(007), 3.547(9)(107), 3.081(6)(315). Wavenumbers
of absorption bands in the infrared spectrum of the new mineral are (cm−1; s is shoulder): 3470, 3420s, 3035, 2960s, 1650, 1426, 1366, 1024, 937, 860, 779, 678, 615s, 553, 449, 386. Results of thermogravimetric
analysis: total weight loss is 42.0 wt %, with three stages of loss: 12.2%, maximum rate at 230°C; 6.1%, maximum rate at 320°C;
and 23.7%, maximum rate at 440°C. Karchevskyite is a late-stage hydrothermal mineral. The mineral is named in memory of Russian
mineralogist Pavel Karchevsky (1976–2002), who made a significant contribution to the study of carbonatites. The type material
of karchevskyite is deposited at the Mineralogical Museum, Division of Mineralogy, St. Petersburg State University, and the
Fersman Mineralogical Museum, Russian Academy of Sciences, Moscow.
Original Russian Text ? S.N. Britvin, N.V. Chukanov, G.K. Bekenova, M.A. Yagovkina, A.V. Antonov, A.N. Bogdanova, N.I. Krasnova,
2007, published in Zapiski Rossiiskogo Mineralogicheskogo Obshchestva, 2007, No. 5, pp. 44–56.
The new mineral karchevskyite and its name accepted by the Commission on New Minerals and Mineral Names, Russian Mineralogical
Society, March 21, 2005. Approved by the Commission on New Minerals and Mineral Names, International Mineralogical Association,
June 30, 2005. 相似文献
19.
The effects of mantle metasomatism on the sulfide phase in mantle xenoliths in general, and on the Os isotopic system in particular, have received increased attention in recent years. Here, we report on Os isotopic systematics of metasomatized mantle xenoliths from the late Quaternary Eifel (Dreiser Weiher and Meerfelder Maar) and neighboring Vogelsberg volcanic fields, which provide insight into the effects of melt extraction and metasomatism on Os isotopes and place constraints on the evolution of the lithospheric mantle component beneath central Europe. Sixteen harzburgite, lherzolite, and pyroxenite xenoliths from the Eifel and two lherzolite xenoliths from the Vogelsberg were analyzed for Os isotopes. Samples from the anhydrous peridotite suite (Ib) are highly variable in their Os isotopes, ranging from subchondritic values (187Os/188Os=0.1236) to suprachondritic values (187Os/188Os=0.1420), indicating that some of these samples have been overprinted by the addition of radiogenic Os and have lost the primary mantle Os that was presumably present. The suprachondritic values suggest a source for this Os in a reservoir with a time-integrated Re/Os ratio greater than that of the bulk Earth. Eifel samples with Os contents >1.5 ng/g from the hydrous suite (Ia) have relatively unradiogenic Os isotope compositions (187Os/188Os=0.1208-0.1237) and Al2O3-Os isotopic systematics consistent with ancient melt depletion and isolation from the convecting asthenospheric mantle for time periods similar to the age of the overlying crust (~1.5 Ga) as well with results from peridotite massifs in the European region. The LREE-metasomatism and the enrichment of Os (up to 6.47 ng/g) and As (sulfide metasomatism?) in the hydrous suite is strongly inversely correlated with the Os isotope ratios, demonstrating that mantle processes such as metasomatism can significantly modify the Os isotope chemistry of mantle xenoliths. 相似文献
20.
Near the village of Engeln, Laacher See area, garnet-bearing pyriclasite and pyribolite ejecta were recognized as constituents of alkaline basaltic tuffs; they are interpreted as fragments of the lowermost crust. During the first main stage of granulite facies metamorphism, assemblages with garnet (Alm47Pyr34Spess2Gross + Andr17), clinopyroxene (Wo37En35Fs15Ts8.5Jd4.5), orthopyroxene I (En34Fs38Ts4Jd2), and plagioclase I (An40-An60) were formed in a temperature range of 730–850°C and rock pressures somewhere between 6.5 and 12 kb, . The rare sulfate-rich meionite, and at least a part of the ubiquitous brown hornblende were presumably also formed during this stage. A retrograde metamorphic event under slightly lower pressures and temperatures led to the breakdown of the assemblage garnet + clinopyroxene thereby forming coronas of plagioclase II . 相似文献