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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. Source


Chukanov N.V.,RAS Institute of Problems of Chemical Physics | Britvin S.N.,Russian Academy of Sciences | Blass G.,Merzbachstrasse 6 | Belakovskiy D.I.,Russian Academy of Sciences | Van K.V.,Russian Academy of Sciences
European Journal of Mineralogy | Year: 2012

The new mineral windhoekite was discovered in a specimen from the Ariskop Quarry, near Windhoek, Namibia. Associated minerals are fluorapophyllite, aegirine, microcline, arisite-(Ce), arisite-(La). Windhoekite is yellow-brown, translucent; streak is beige. It forms isolated long-prismatic crystals up to 0.15 × 4 mm and their radial aggregates in cavities in phonolite. D calc is 2.630 g/cm 3, D meas is 2.62 (2) g/cm 3. The new mineral is biaxial (-), α = 1.610(3), β = 1.662(3), γ = 1.671(3), 2V (meas.) = 50(10)°, 2V (calc.) = 44°. Dispersion is not observed, pleochroism is strong (Y ≈ Z > X, brown to dark brown), orientation: X ≈ α; Z = c. The IR spectrum is given. The chemical composition is (electron microprobe, mean of 5 analyses, wt%): CaO 9.24, MnO 0.85, Fe 2O 3 23.14, Al 2O 3 0.41, SiO 2 46.32, H 2O (by gas chromatography) 21.0; total 100.96. The empirical formula based on 34 O atoms is: (Ca 1.68Mn 0.12)Fe 3+ 2.96(Si 7.87Al 0.08O 20)(OH) 4 10H 1.98O. The simplified formula is: Ca 2Fe 3+ 3-x[(Si,Al) 8O 20](OH) 4 10H 2O. The crystal structure was solved using single-crystal diffraction data. Windhoekite is monoclinic, space group C2/m, α = 14.319(5), β = 17.825(4), c = 5.242(1) Å , β = 103.5(2), V = 1301.0(6) Å 3, Z = 2. Ca and Fe 3+ occupy two large octahedra and two smaller octahedra, respectively. The strongest lines of the powder diffraction pattern [d, Å (I, %) (hkl)] are: 11.04 (100) (110), 4.432 (10) (021), 4.133 (6) (22-1), 3.754 (4) (240), 3.486 (11) (400), 2.636 (8) (35-1), 2.551 (4) (002), 2.505 (6) (26-1). Type material is deposited in the collections of the Fersman Mineralogical Museum of the Russian Academy of Sciences, Moscow, Russia, under registration number 4018/1. © 2011 E. Schweizerbart'sche Verlagsbuchhandlung. Source


Kolitsch U.,Mineralogisch Petrographische Abt. | Kolitsch U.,University of Vienna | Mills S.J.,Khan Research Laboratories | Miyawaki R.,National Museum of Science and Nature | Blass G.,Merzbachstrasse 6
European Journal of Mineralogy | Year: 2012

The new mineral ferriallanite-(La) (IMA 2010-066), ideally CaLaFe 3+ AlFe2+ (SiO4)(Si2O 7)O(OH), is a member of the epidote supergroup and the La analogue of ferriallanite-(Ce). It occurs as a single, thick, tabular {100} crystal (2 mm in its longest dimension) in a void of a sanidinite xenolith found in the In den Dellen pumice quarries, Niedermendig, Mendig, Laach Lake volcanic complex, Eifel Mountains, Rhineland-Palatinate, Germany. Ferriallanite-(La) is associated with sanidine, minor "biotite", magnetite, nosean (grey, rounded grains) and trace amounts of dark green clinopyroxene. It is black, translucent in very thin splinters, with a brown streak, vitreous lustre, no cleavage, irregular to conchoidal fracture, Mohs hardness of ca. 6, Dcalc. = 4.208 g cm-3 (for empirical formula) and Dx=4.099 g cm-3. Optically, it is biaxial negative, with α=1.791(5), β= 1.827(6), γ=1.845(5) (white light), 2Vα (calc.) = 69°. The mineral is non-fluorescent and shows strong pleochroism, X = pale brownish, Y = greyish brown, Z = dark red-brown; absorption Z > Y ≫ X, orientation unknown. Dispersion is weak and the sign could not be determined. Electron microprobe analysis yielded the empirical formula (based on 12 O atoms and 1 OH group pfu): Ca0.98(La0.47Ce0.41Th 0.08Nd0.02Pr0.02)∑1.00(Fe 3+ 0.81Al0.14)∑0.95Al 1.00(Fe2+ 0.47Mn0.28Ti 0.16Mg0.05)∑0.96[(Si0.93Al 0.05)∑0.98O4](Si2O 7)O(OH). Ferriallanite-(La) is monoclinic, space group P2 1/m, with a = 8.938(2), b = 5.789(1), c = 10.153(2) Å ,β = 114.54(3)°, V = 477.88(6) Å 3 (single-crystal data) and Z = 2. Strongest eight lines in the X-ray powder diffraction pattern are [d in Å (I) hkl]: 9.22 (19) 001; 7.96 (34) 1̄01; 3.53 (38) 2̄11; 2.92 (100) 3̄02, 1̄13; 2.72 (50) 120, 013; 2.63 (36) 3̄11; 2.16 (17) 221 and 1.639 (34) 1̄06, 4̄24. A single-crystal X-ray structure refinement [R1(F) = 0.0150] and a derivation of the M3 site population from the chemical-analytical data yielded the formula A1Ca1.00 A2(La0.49Ce0.42Ca0.09) M1(Fe0.58Al0.42)M2(Al 0.94Fe0.06)M3(Fe0.49Mn 0.29Ti0.17Mg0.05)∑1.00(SiO 4)(Si2O7)O(OH), in reasonably good agreement with the electron microprobe data. The site refinements clearly show that there is some minor Fe at the M2 site, in contrast to the formula calculated using currently recommended methods for members of the epidote supergroup. © 2012 E. Schweizerbart'sche Verlagsbuchhandlung, D-70176 Stuttgart. Source


Chukanov N.V.,RAS Institute of Problems of Chemical Physics | Blass G.,Merzbachstrasse 6 | Pekov I.V.,Moscow State University | Belakovskiy D.I.,Russian Academy of Sciences | And 3 more authors.
Geology of Ore Deposits | Year: 2012

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), 2Vmeas = 50(10)°, 2Vcalc = 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(Fe0. 53 2+Mn0. 38Mg0. 08)Σ0. 99(Ti2. 44Fe0. 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) (3 11), 2. 96 (100) (3 13, 311), 2. 80 (50) (020), 2. 14 (50) (4 22, 3 15, 313), 1. 947 (50) (024, 223), 1. 657 (40) (4 07, 3 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. © 2012 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

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