Aleksandr E. Zadov

Chukanovite, Fe2(CO3)(OH)2, a new mineral from the weathered iron meteorite Dronino

The new mineral chukanovite, Fe 2 (CO 3 )(OH) 2 , occurs in cavities of weathered fragments of the Dronino ataxite iron eteorite found near the Dronino village, Kasimov district, Ryazan’ Oblast, Russia. It is a product of terrestrial alteration of meteorite iron. Associated minerals are goethite, akaganeite, hematite, hibbingite, reevesite, honessite, etc . Chukanovite forms acicular to fibrous individuals (up to 0.5 mm long and up to 2–3 μm thick) combined in spherulites up to 1 mm in diameter, botryoidal spherulitic clusters and parallel- or radial-columnar aggregates which form crusts up to 1 mm thick. Unaltered chukanovite is transparent, pale-green or colourless. The surface of aggregates is brownish-green. Streak is white. Lustre is vitreous. Cleavage is perfect, probably on {0–21}, fracture is uneven. The mineral is brittle, the Mohs’ hardness is 3.5–4, the calculated density is 3.60 g/cm 3 . It is optically biaxial (−) with α1.673(3), β1.770(5), γ1.780(5), 2 V meas. 10(5)°. Average chemical composition (wt. %; electron probe, H 2 O by modified Penfield method, CO 2 by selective sorption) is: MgO 0.1, FeO 68.8, NiO 0.6, CO 2 19.8, H 2 O 10.9, total 100.2. The empirical formula calculated on the basis of two metal atoms is (Fe 2+ 1.97 Ni 0.02 Mg 0.01 ) ∑2.00 (CO 3 ) 0.93 (OH) 2.14 ·0.18H 2 O, ideally Fe 2 (CO 3 )(OH) 2 . Chukanovite is monoclinic P 2 1 / a , with a = 12.396(1) A, b = 9.407(1) A, c = 3.2152(3) A, β = 97.78°. The strongest lines of the X-ray powder pattern [ d (A), I, ( hkl )] are: 6.14, 40, (200); 5.15, 60, (231); 3.73, 80, (310); 2.645, 100, (230); 2.361, 40, (510); 2.171, 40, (520). The structure of chukanovite was refined on synchrotron data by the Rietveld method up to Rp = 3.43 %, wRp = 4.51 %, R Bragg = 2.48 %. Chukanovite is closely related to the minerals of the malachite-rosasite group. It was named in honour of Nikita V. Chukanov (b. 1953), Russian physicist and mineralogist. The holotype specimen is deposited in the Fersman Mineralogical Museum of the Russian Academy of Sciences, Moscow.

Vorlanite (CaU6+O4) - A new mineral from the Upper Chegem caldera, Kabardino-Balkaria, Northern Caucasus, Russia

Abstract The new mineral vorlanite, (CaU6+)O4, Dcalc = 7.29 g/cm3, H = 4-5, VHN10 = 360 kg/mm2, was found near the top of Mt. Vorlan in a calcareous skarn xenolith in ignimbrite of the Upper Chegem caldera in the Northern Caucasus, Kabardino-Balkaria, Russia. Vorlanite occurs as aggregates of black platy crystals up to 0.3 mm long with external symmetry 3̄m. The strongest powder diffraction lines are [d(Å)/(hkl)]: 3.107/(111), 2.691/(200), 1.903/(220), 1.623/(311), 1.235/(331), 1.203/(420), 1.098/(422), 0.910/(531). Single-crystal X-ray study gives isometric symmetry, space group Fm3̄m, a = 5.3813(2) Å, V = 155.834(10) Å3, and Z = 2. X-ray photoelectron spectroscopy indicate that all U in vorlanite is hexavalent. The mineral is isostructural with fluorite and uraninite (U4+O2). In contrast to synthetic rhombohedral CaUO4, and most U6+ minerals, the U6+ cations in vorlanite are present as disordered uranyl ions. [8]Ca2+ and [8]U6+ are disordered over a single site with average M-O = 2.33 Å. Vorlanite is believed to be a pseudomorphic replacement of originally rhombohedral CaUO4. We assume that this rhombohedral phase transformed by radiation damage to cubic CaUO4 (vorlanite). The new mineral is associated with larnite, chegemite, reinhardbraunsite, lakargiite, rondorfite, and wadalite, which are indicative of high-temperature formation (>800 °C) at shallow depth.

Toturite Ca3Sn2Fe2SiO12—A new mineral species of the garnet group

Abstract A new Sn-rich garnet, toturite Ca3Sn2Fe2SiO12, occurs as an accessory mineral in high-temperature altered carbonate-silicate xenoliths in ignimbrite of the Upper Chegem structure in the Northern Caucasus, Kabardino-Balkaria, Russia. The empirical formula of toturite from the holotype sample is (Ca2.989Fe2+0.011)Σ3(Sn4+1.463Sb5+0.325Ti4+0.193Zr0.013Mg0.003Nb5+0.002Cr0.001)Σ2(Fe3+1.633Al0.609Si0.552Ti4+0.166Fe2+0.039V5+0.001)Σ3O12. The mineral forms thin regular growth zones and irregular spots in the Fe3+-dominant analog of kimzeyite. Toturite is cubic, Ia3̅d, a ≈ 12.55 Å, as is confirmed by electron backscatter diffraction (EBSD) data. The strongest lines of the calculated powder diffraction pattern are [d, Å (hkl) I]: 2.562 (422) 100, 1.677 (642) 91, 3.138 (400) 74, 4.437 (220) 67, 1.146 (10.4.2) 31, 1.046 (884) 25, 1.984 (620) 23. Raman spectra of toturite are analogous to those of kimzeyite and shows the following diagnostic bands (cm-1): 244, 301, 494, 497, 575, 734. The association of toturite with larnite, rondorfite, wadalite, magnesioferrite, lakargiite, and cuspidine indicates a high temperature (>800 °C) of formation. The mineral name is given after the Totur River situated in Eltyubyu village, also Totur is the name of a Balkarian god.

Larisaite, Na(H3O)(UO2)3(SeO3)2O2·4H2O, a new uranyl selenite mineral from Repete mine, San Juan County, Utah, U.S.A.

Larisaite, a new uranyl selenite with the idealized formula Na(H3O)(UO2)3(SeO3)2O2 · 4H2O, has been found in a sedimentary rock from Repete mine near Blanding, San Juan Co., Utah, U.S.A., in association with quartz, haynesite, andersonite, wolsendorfite, uranophane, gypsum, calcite and montmorillonite. The mineral is named in memory of Russian mineralogist and crystallographer Larisa Nikolaevna Belova (1923–1998) who made a significant contribution to the knowledge on the uranium minerals. Larisaite forms coarse lamellar crystals up to 1 mm and radial aggregates up to 2 mm. It is transparent or translucent, yellow, lustre vitreous, streak yellow. Fluorescence under the UV light is green (wavelengths of excitation 250 nm). Larisaite is sectile, with Mohs hardness 1, perfect cleavage on (010) and uneven fracture across the cleavage direction. Calculated density is 4.50 g/cm3 from the crystal structure refinement and 4.46 g/cm3 from the empirical formula. Optically biaxial (−), α 1.597(2), β 1.770(5), γ 1.775(5); −2V = 20°. Dispersion is strong, r α (light greenish-yellow). IR spectrum is given. Average values for 3 point microprobe analyses (wt.%, ranges are given in brackets) are: Na2O 2.04 (1.82–2.32), K2O 0.69 (0.62–0.76), CaO 0.23 (0.17–0.30), UO3 72.19 (71.77–72.64), SeO2 18.12 (17.83–18.48); H2O content determined by Penfield method is 7.64; total 100.91 wt.%; contents of Mg, Sr, Ba, Pb, Zn, Mn, Ni, Co, Cu, Fe, Al, Si, S, As, Cl, F are lower than detection limits i. e. 2)3.09(SeO3)2O24.1H20.1-(Kp/Kc) = 0.013 (“superior”). The crystal structure has been determined (R=0.067). Larisaite is monoclinic, space group P 11 m ; a = 6.9806(9), b = 7.646(1), c = 17.249(2) A, γ = 90.039(4)°, V = 920.64 A3, Z = 2. The strongest lines in the powder diffraction pattern [ d , A ( I , %) ( hkl )] are: 8.63 (43) (002), 7.67 (100) (010), 3.85 (40) (−113, 020, 113), 3.107(77) (211), 2.874 (53) (006, −115). By the U: Se ratio, the values of unit cell parameters and the structure type, larisaite is related to haynesite, guilleminite and piretite. In common with guilleminite, uranium polyhedra and SeO3 triangles form the sheets, however the distribution of interlayer cations and H2O molecules is different. Holotype specimen is deposited in the Geoscientific Collections of Freiberg University of Mining and Technology, Faculty of Geosciences, Geotechnics and Mining, Freiberg, Germany (the inventory number 80251).

Fluorcalciobritholite, Ca,REE)5[(Si,P)O4]3F, a new mineral: description and crystal chemistry

The new mineral fluorcalciobritholite, ideally Ca 3 Ce 2 (SiO 4 ) 2 (PO 4 )F, has been found at Mount Kukisvumchorr, Khibiny alkaline complex, Kola Peninsula, Russia, in veinlets which contains aggregates of orthoclase, nepheline, sodalite and biotite in association with grains of fayalite, gadolinite-(Ce), zircon, monazite-(Ce), zirconolite (“polymignite”), fluorapatite, fluorite, molybdenite, lollingite and graphite. Fluorcalciobritholite forms long-prismatic hexagonal crystals up to 0.5 x 10 mm; the main crystal form is the hexagonal prism {10–10}. The mineral is transparent, with a pale pinkish to brown colour and a white streak. The hardness (Mohs) is 5.5, and the observed density is 4.2(1) g/cm 3 . Optically, it is uniaxial (−) with ω 1.735(5), e 1.730(5). Electron microprobe gave the following empirical formula based on [Si+P+S] = 3 apfu : [Ca 2.80 (Ce 0.93 La 0.54 Nd 0.26 Y 0.18 Pr 0.08 Sm 0.03 Gd 0.03 Dy 0.02 Yb 0.02 Er 0.01 ) ∑2.12 Th 0.04 Mn 0.03 Sr 0.02 ] ∑4.99 [(Si 1.94 P 1.06 ) ∑3 O 12 ] [F 0.76 O 0.22 Cl 0.01 ] ∑0.99 (Z = 2). The IR spectrum of metamict fluorcalciobritholite from Siberia showed a marked similarity with those of hydroxylbritholite-(Ce) and hydroxylbritholite-(Y). The strongest lines of the X-ray powder pattern [ d in A ( I ) ( hkl )] are: 3.51 (45) 002, 3.15 (70) 102, 2.85 (100) 211, 121, 2.78 (60) 300. The mineral is hexagonal, space group P 6 3 / m , with a = 9.580(7), c = 6.985(4) A, V = 555.2(7) A 3 . The crystal structure was refined from single-crystal X-ray diffraction data to R F = 0.029. Fluorcalciobritholite, whose simplified formula is (Ca,REE) 5 [(Si,P)O 4 ] 3 F, differs from fluorbritholite in having Ca > ∑REE, and differs from fluorapatite in having Si > P. Its compositional field falls within the limits Ca 2.5 REE 2.5 (SiO 4 ) 2.5 (PO 4 ) 0.5 F (boundary with fluorbritholite) and Ca 3.5 REE 1.5 (SiO 4 ) 1.5 (PO 4 ) 1.5 F (boundary with fluorapatite). Both the mineral and its name have been approved by the IMA Commission on New Minerals and Mineral Names.

Lileyite, Ba2(Na,Fe,Ca)3MgTi2(Si2O7)2O2F2, a new lamprophyllite-group mineral from the Eifel volcanic area, Germany

The new Mg- and F-dominant lamprophyllite-group mineral lileyite (IMA 2011-021) was found at the Lohley quarry, Udersdorf, 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, gotzenite. 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 2 O 6.75, MgO 4.58, FeO 4.48, CaO 2.30, SrO 2.23, MnO 1.44, K 2 O 1.41, Nb 2 O 5 0.95, F 3.88, –O=F 2 -1.63; total 99.36. The empirical formula based on 18 anions is: Ba 1.50 Sr 0.19 K 0.26 Na 1.89 Ca 0.36 Mn 0.18 Mg 0.99 Fe 0.54 Ti 2.01 Nb 0.06 Si 4.06 O 16.23 F 1.77 . The simplified formula is: Ba 2 (Na,Fe,Ca) 3 MgTi 2 (Si 2 O 7 ) 2 O 2 F 2 . The crystal structure was solved using single-crystal X-ray diffraction data ( R = 0.024). Lileyite is monoclinic, space group C 2/ m , a = 19.905(1), b = 7.098(1), c = 5.405(1) A, β = 96.349(5)°, V = 758.93(6) A 3 , Z = 2. The strongest lines of the powder diffraction pattern [ d , A ( 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.

Rusinovite, Ca10(Si2O7)3Cl2: a new skarn mineral from the Upper Chegem caldera, Kabardino-Balkaria, Northern Caucasus, Russia

Rusinovite, Ca 10 (Si 2 O 7 ) 3 Cl 2 , was discovered in an altered carbonate-silicate xenolith enclosed in ignimbrites of the Upper Chegem volcanic caldera. The mineral is named after Vladimir Leonidovich Rusinov (1935–2007), a Russian petrologist and expert in the field of thermodynamics of non-equilibrium mineral systems. A synthetic analogue of rusinovite is also known. The new mineral has an OD structure of which only the average structure could be determined based on strong and sharp reflections recorded by single-crystal X-ray diffraction: space group Cmcm , a = 3.7617(2), b = 16.9385(8), c = 17.3196(9) A, V = 1103.56(10) A 3 , Z = 2. The average structure ( R 1 = 3.18 %) is characterized by columns of face-sharing disilicate units extending parallel to a . However, in the true structure only each second (Si 2 O 7 ) unit is occupied. Although rusinovite has a stoichiometry similar to the apatite-group mineral nasonite, Pb 6 Ca 4 (Si 2 O 7 ) 3 Cl 2 , the two structures are considerably different. Rusinovite has following optical properties: α = 1.645(2), β = 1.664(2), γ = 1.675(3); Δ = 0.030, 2V meas = −75(10) °; 2V calc = −74.6 °; the Mohs hardness is 4–5, the density is 2.91 g/cm 3 . The mineral forms fibrous crystals often intergrown into spherolites and displays good cleavage parallel to (010). The Raman spectrum of rusinovite strongly resembles that of another skarn calcium-disilicate: rankinite, Ca 3 Si 2 O 7 .

Pavlovskyite Ca8(SiO4)2(Si3O10): A new mineral of altered silicate-carbonate xenoliths from the two Russian type localities, Birkhin massif, Baikal Lake area and Upper Chegem caldera, North Caucasus

Abstract The new mineral pavlovskyite Ca8(SiO4)2(Si3O10) forms rims together with dellaite Ca6(Si2O7)(SiO4)(OH)2 around galuskinite Ca7(SiO4)3CO3 veins cutting calcio-olivine skarns in the Birkhin gabbro massif. In addition, skeletal pavlovskyite occurs in cuspidine zones of altered carbonate xenoliths in the ignimbrites of the Upper Chegem caldera (North Caucasus). The synthetic analog of pavlovskyite has been synthesized before and is known from cement-like materials. Isotypic to pavlovskyite is the synthetic germanate analog Ca8(GeO4)2(Ge3O10). The crystal structure of pavlovskyite, space group Pbcn, a = 5.0851(1), b = 11.4165(3), c = 28.6408(8) Å, V = 1662.71(7) Å3, Z = 4, has been refined from X-ray single-crystal data to R1 = 3.87%. The new colorless mineral has a Mohs hardness of 6-6.5, biaxial (-), α = 1.656(2), β = 1.658(2), γ = 1.660(2) (589 nm), 2V (meas) = 80(5)°, 2V (calc) = 89.9°, medium dispersion: r > v, optical orientation: X = b, Y = c, Z = a. For comparison with pavlovskyite, the crystal structure of kilchoanite Ca6(SiO4)(Si3O10) from the Birkhin massif [space group I2cm, a = 11.4525(2), b = 5.0867(1), c = 21.996(3) Å, V = 1281.40(4) Å3, Z = 4] has been refined from single-crystal X-ray data to R1 = 2.00%. Pavlovskyite represents a 1:1 member of a polysomatic series with calcio-olivine γ-Ca2SiO4 and kilchoanite Ca6(SiO4)(Si3O10) as end-member modules. The structure is characterized by strongly folded trisilicate units (Si3O10) interwoven with a framework of CaO6 and CaO8 polyhedra. Olivine-like slices with orthosilicate groups are interstratified with the characteristic trisilicate module of Ca4(Si3O10) composition. Although the optical properties of pavlovskyite and kilchoanite are similar, both minerals can be distinguished by chemical analyses (different Ca/Si ratio), X-ray diffraction, and Raman spectroscopy. The new mineral is named after V.E. Pavlovsky (1901-1982), an outstanding geologist in the area of Eastern Siberia, in particular of the Baikal region.

Edgrewite Ca9(SiO4)4F2-hydroxyledgrewite Ca9(SiO4)4(OH)2, a new series of calcium humite-group minerals from altered xenoliths in the ignimbrite of Upper Chegem caldera, Northern Caucasus, Kabardino-Balkaria, Russia

Abstract Members of the edgrewite Ca9(SiO4)4F2-hydroxyledgrewite Ca9(SiO4)4(OH)2 series, structural analogues of clinohumite-hydroxylclinohumite series, Mg9(SiO4)4(F,OH)2, were discovered in xenoliths of carbonate-silicate rock altered to skarn within ignimbrites of the Upper Chegem volcanic structure, Kabardino-Balkaria, Northern Caucasus, Russia. The new minerals occur sparingly in zones containing bultfonteinite, hillebrandite, jennite, and chegemite, as well as rare relics of larnite and rondorfite enclosed in a matrix of hydroxylellestadite. Edgrewite and hydroxyledgrewite are largely altered to jennite in places with admixed zeophyllite and trabzonite, and are preserved as elongate relics mostly 0.1-0.4 mm long in the central part of atoll-like pseudomorphs. The new minerals form a solid-solution series Ca9(SiO4)4(F,OH)2, in which the content of the edgrewite end-member Ca9(SiO4)4F2 ranges from 74% (F = 3.64 wt%) to 31% (F = 1.52 wt%). Structure refinement of crystals containing 51% and 37% of the edgrewite end-member gave, respectively, R1 = 3.03%, space group P21/b11 (no. 14), Z = 2, a = 5.06870(10), b = 11.35790(10), c = 15.4004(2) Å, α = 100.5980(10)°, V = 871.47(3) Å3; and R1 = 1.61%, space group P21/b11 (no. 14), Z = 2, a = 5.06720(10), b = 11.35450(10), c = 15.3941(2) Å, α = 100.5870(10)°, and V = 870.63(2) Å3. Minerals of the edgrewite-hydroxyledgrewite series are colorless, optically biaxial (+), 2Vmeas = 80(5)°; 2Vcalc = 78.7°; dispersion r > v, medium; orientation: Z = a, X ^ c = 12(2)°; edgrewite: α = 1.621(2), β = 1.625(2), γ = 1.631(2); hydroxyledgrewite: α = 1.625(2), β = 1.629(2), γ = 1.635(2) (589 nm). The micro-hardness VHN50 = 352-366 kg/mm2 corresponds to the Mohs scale of 5.5-6. 5. FTIR spectra of edgrewite and hydroxyledgrewite show resolved bands at (edgrewite/hydroxyledgrewite, cm-1): 3558 and 3551 and 3543/3554, absent/3486, 1075/1075, 996/996, 980/982, 934/933, 917/918, 904/903, 890/884, 864/864, 842/842, 818/820. Raman spectra are characterized by the following bands (edgrewite/hydroxyledgrewite, cm-1) at: 921/923, 889/890, 839/840, and 815/814 (SiO4 stretching), at: 556/559, 527/527, 423/419, 406/404, and 394/394 (SiO4 bending), 309/295, 269/256, and 163/166 (CaO6). In the OH stretching region three bands are noted at 3554, 3547, and 3540 cm-1 for edgrewite and two - 3550 and 3475 cm-1 for hydroxyledgrewite confirming the corresponding IR spectra. The major difference in Raman and IR spectra of edgrewite and hydroxyledgrewite is the presence of two resolved peaks in the OH stretching region at ca. 3550 and 3480 cm-1 for hydroxyledgrewite.

Eltyubyuite, Ca12Fe3+10Si4O32Cl6 – the Fe3+ analogue of wadalite: a new mineral from the Northern Caucasus, Kabardino-Balkaria, Russia

Eltyubyuite (IMA2011-022), ideally Ca 12 Fe 3+ 10 Si 4 O 32 Cl 6 i.e . the Fe 3+ analogue of wadalite, Ca 12 Al 10 Si 4 O 32 Cl 6 , was discovered in altered silicate-carbonate xenoliths in the diatreme facies of ignimbrites in the Upper Chegem caldera, Kabardino-Balkaria, Northern Caucasus, Russia. Eltyubyuite forms light-brown or yellow crystals with tetrahedral habit up to 10 μm across in rondorfite or larnite grains and commonly overgrows wadalite. Associated minerals are hydroxylellestadite, edgrewite-hydroxyledgrewite, chegemite-fluorchegemite, cuspidine, lakargiite, perovskite, kerimasite, srebrodolskite and dovyrenite. Eltyubyuite formed by contact metamorphism of calcareous sediments under sanidinite-facies conditions ( T > 800°C, P 2 9.57(0.32), TiO 2 0.48(0.27), Al 2 O 3 3.45(1.81), MgO 0.08(0.07), CaO 36.84(0.91), Fe 2 O 3 , Cl 9.60(0.48); O = Cl −2.13, Sum 98.26, and an empirical formula based on 26 cations, Ca 12.12 Mg 0.04 Ti 0.11 Fe 9.41 Al 1.26 Si 2.98 O 31.89 Cl 5.04 , which simplifies to Ca 12 (Fe 3+ , Al) 11 Si 3 O 32 Cl 5 . Electron-back-scattered diffraction yields isometric symmetry, space group I 4 d (no. 220), a = 12.20(3) A, V = 1815.85(9) A 3 , Z = 2. Calculated density and refractive index are 3.349 g/cm 3 and 1.85, respectively. The main bands in Raman spectra of eltyubyuite are attributed to [Fe 3+ O 4 ] 5− : 700–710 cm −1 (stretching vibrations), 460–470 cm −1 (bending vibrations), whereas bands −1 are assigned to Ca-O and Ca-[Fe 3+ O 4 ] 5− vibrations. The mineral is named for the Balkarian village Eltyubyu, which is situated near the type locality. Eltyubyuite has subsequently been found in altered xenoliths within volcanic rocks of Eifel, Germany and Kel’ Highland (volcano Shadil-Khokh), Southern Ossetia.