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532 results on '"Britvin, Sergey N."'

1. Meteoritic Tutton salt, a naturally inspired reservoir of cometary and asteroidal ammonium

Author

Britvin, Sergey N., Vereshchagin, Oleg S., Vlasenko, Natalia S., Krzhizhanovskaya, Maria G., and Ivanova, Marina A.

Subjects
Astrophysics - Earth and Planetary Astrophysics, Physics - Geophysics
Abstract

The lack of benchmark data on the real minerals, native ammonium carriers in Solar System gives rise to controversial opinions on extraterrestrial ammonium reservoirs. We herein report on discovery of the first mineral carrier of meteoritic ammonium and show its relevance to the compositional and spectral characteristics of cometary and asteroidal bodies. Chemically distant from previously inferred volatile organics or ammoniated phyllosilicates, it is an aqueous metal-ammonium sulfate related to a family of so-called Tutton salts. Nickeloan boussingaultite, (NH4)2(Mg,Ni)(SO4)2 6H2O, occurs in Orgueil, a primitive carbonaceous chondrite closely related to (162173) Ryugu and (101955) Bennu, the C-type asteroids. The available spectroscopic, chemical and mineralogical data signify that natural Tutton salts perfectly fit into the role of ammonium reservoir under conditions of cometary nuclei and carbonaceous asteroids.

Published
2024

6. Cafeosite, Ca4Fe2+3Fe3+2□O6S4, a new meteoritic oxysulfide, a redox indicator of metamorphic alteration of carbonaceous asteroids.

Author

Ivanova, Marina A., Britvin, Sergey N., Gulyaeva, Roza I., Petrova, Sofia A., Zinovieva, Nina G., Kozlov, Vladimir V., Tyushnyakov, Stanislav N., and Kasatkin, Anatoly V.

Subjects
*PYRRHOTITE, *MINERALS, *IRON oxidation, *OXIDATION states, *CRYSTAL structure, *CHROMITE, *OLIVINE
Abstract

A natural iron‐bearing oxysulfide, named сafeosite after its chemical composition, is a unique example of a mineral that simultaneously contains iron in three oxidation states: Fe3+, Fe2+, and intermediate between Fe2+ and Fe0 involved in metallic‐type FeFe bonding. Cafeosite was discovered in metamorphosed carbonaceous chondrite Dhofar 225, which is classified as CM‐anomalous but likely related to the CY (Yamato‐type) group. The mineral occurs as tiny anhedral grains that coalesce into irregular aggregates up to 20 μm, commonly encrusted by micrometer‐thick troilite or pyrrhotite rims. The grains are randomly disseminated within a chondrite matrix composed of thermally altered phyllosilicates. Associated accessory minerals are troilite, pyrrhotite, Fe‐rich, Al‐bearing olivine, unknown Al‐bearing Fe sulfide, Al‐rich chromite, kamacite, awaruite, pentlandite, escolaite, and perovskite. In reflected light, cafeosite is gray, with no internal reflections. Anisotropy is moderate, bireflectance in gray hues. Infrared microspectroscopy did not reveal any bands attributable to (OH)−, H2O or CO32− vibrations. Owing to the small grain size, the crystal structure of the mineral has been studied using synthetic analog, which was found to be isostructural with natural cafeosite based on electron backscatter diffraction (EBSD) data. Cafeosite is orthorhombic, space group Cmce (#64), a 17.4856(9), b 11.1516(5), c 11.1543(5) Å, V 2175.0(2) Å3, Z = 8, Dx = 4.11 g cm−3. The crystal structure has been solved and refined to R1 = 0.039 for 1105 unique reflections. Chemical composition of both natural and synthetic cafeosite corresponds to the formula Ca4Fe2+3Fe3+2(□1−xFex)O6S4 where (□1−xFex) denotes structural vacancy partially occupied by semimetallic‐type Fe (x = 0.2–0.3). The ideal endmember formula of the mineral is Ca4Fe2+3Fe3+2□O6S4. Cafeosite was likely formed from previously altered precursor material of Dhofar 225, which, like common CM chondrites, consisted of phyllosilicates, Ca‐bearing carbonates, tochilinite‐like sulfides–hydroxides and pyrrhotite. During thermal metamorphism at temperatures between 750 and 900°C, sulfides–hydroxides were partly sintered with calcined carbonates and iron oxides, resulting in cafeosite formation. Due to varying and redox‐dependent contents of Fe3+ and Fe2+, as well as the presence of metallic‐type Fe in the structure, cafeosite could be regarded as a single‐phase redox indicator alternative to the known triple‐phase buffers, for example, iron–magnetite–pyrrhotite (IM‐Po), iron–wüstite–pyrrhotite (IW‐Po) and magnetite–wüstite–pyrrhotite (MW‐Po) systems. Discovery of cafeosite provides insight into a previously obscured aspect of CY‐chondrite formation: the redox conditions of thermal metamorphism on carbonaceous asteroids. [ABSTRACT FROM AUTHOR]

Published
2024
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12. A New Mineral Calcioveatchite, SrCaB 11 O 16 (OH) 5 ·H 2 O, and the Veatchite–Calcioveatchite Isomorphous Series.

Author

Pekov, Igor V., Zubkova, Natalia V., Apollonov, Vladimir N., Yapaskupt, Vasiliy O., Britvin, Sergey N., and Pushcharovsky, Dmitry Yu.

Subjects
BORATE minerals, CRYSTAL structure, MAGNESITE, ELECTRON probe microanalysis, X-ray diffraction
Abstract

The new mineral calcioveatchite, ideally SrCaB11O16(OH)5·H2O, is a Ca-Sr-ordered analogue of veatchite. It was found at the Nepskoe potassium salt deposit, Irkutsk Oblast, Siberia, Russia in halite-sylvite and sylvite-carnallite rocks, with boracite, hilgardite, kurgantaite, hydroboracite, volkovskite, veatchite, anhydrite, magnesite, and quartz. Calcioveatchite forms prismatic or tabular crystals up to 1 × 1.5 × 3 mm3 and crystal clusters up to 3 mm across. It is transparent and colourless with vitreous lustre. Calcioveatchite is brittle, cleavage is perfect on {010}, the Mohs' hardness is ca 2, Dmeas is 2.58(1), and Dcalc is 2.567 g cm−3. Calcioveatchite is optically biaxial (+), α = 1.543(2), β = 1.550(5), γ = 1.626(2), 2Vmeas = 30(10)°, and 2Vcalc = 35°. The average chemical composition (wt.%, electron microprobe, H2O calculated by stoichiometry) is: CaO 7.05, SrO 20.70, B2O3 61.96, H2O 10.22, and total 99.93. The empirical formula, calculated based on 22 O apfu = O16(OH)5(H2O) pfu, is Sr1.23Ca0.78B10.99O16(OH)5·H2O. Calcioveatchite is monoclinic, space group P21, a = 6.7030(3), b = 20.6438(9), c = 6.6056(3) Å, β = 119.153(7)°, V = 798.26(8) Å3, and Z = 2. Polytype: 1M. The strongest reflections of the powder XRD pattern [d,Å(I,%)(hkl)] are: 10.35(100)(020), 5.633(12)(110), 5.092(10)(120), 3.447(14)(060), 3.362(13)(101, 051), 3.309(38)(–102), 2.862(10)(012), and 2.585(19)(080). The crystal structure was solved based on single-crystal XRD data, R1 = 0.0420. Calcioveatchite (calcioveatchite-1M) is an isostructural analogue of veatchite-1M with the 11-fold cation polyhedron occupied mainly by Sr [Sr0.902(8)Ca0.098(8)] whereas the 10-fold polyhedron is Ca dominant [Ca0.686(7)Sr0.314(7)]. The chemical composition of veatchite from five localities in Russia (Nepskoe), Kazakhstan (Shoktybay and Chelkar in the North Caspian Region), and the USA (Tick Canyon and Billie Mine in California) was studied, and it is shown to exist in nature as a continuous, almost complete isomorphous series which extends from Ca-free veatchite, Sr2B11O16(OH)5·H2O, to calcioveatchite with the composition Sr1.14Ca0.87B10.99O16(OH)5·H2O. [ABSTRACT FROM AUTHOR]

Published
2024
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13. Amableite-(Ce), Na15[(Ce1.5Na1.5)Mn3]Mn2Zr3◻Si[Si24O69(OH)3](OH)2⋅H2O, a new eudialyte-group mineral from Saint-Amable Sill, Québec, Canada

Author

Chukanov, Nikita V., primary, Zolotarev, Andrey A., additional, Schäfer, Christof, additional, Varlamov, Dmitry A., additional, Pekov, Igor V., additional, Vigasina, Marina F., additional, Belakovskiy, Dmitry I., additional, Aksenov, Sergey M., additional, Vozchikova, Svetlana A., additional, and Britvin, Sergey N., additional

Published
2024
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37. New arsenate minerals from the Arsenatnaya fumarole, Tolbachik volcano, Kamchatka, Russia. XX. Evseevite, Na2Mg(AsO4)F, the first natural arsenate with an antiperovskite structure

Author

Pekov, Igor V., primary, Zubkova, Natalia V., additional, Agakhanov, Atali A., additional, Vigasina, Marina F., additional, Yapaskurt, Vasiliy O., additional, Britvin, Sergey N., additional, Turchkova, Anna G., additional, Sidorov, Evgeny G., additional, Zhitova, Elena S., additional, and Pushcharovsky, Dmitry Yu., additional

Published
2023
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45. Microwave-Assisted Synthesis of Titanosilicates Using a Precursor Produced from Titanium Ore Concentrate.

Author

Kalashnikova, Galina O., Gryaznova, Darya V., Baranchikov, Alexander E., Britvin, Sergey N., Yakovenchuk, Victor N., Samburov, Gleb O., Veselova, Varvara O., Pulyalina, Aleksandra Y., Pakhomovsky, Yakov A., Bazai, Ayya V., Glazunova, Margarita Y., Shirokaya, Anna A., Kozerozhets, Irina V., Nikolaev, Anatoly I., and Ivanov, Vladimir K.

Subjects
TITANIUM ores, AMMONIUM sulfate, CESIUM ions, ORES
Abstract

Titanosilicates comprise a broad class of materials with promising technological applications. The typical obstacle that restricts their industrial applicability is the high manufacturing cost due to the use of specific organotitanium precursors. We herein report a new approach to the synthesis of titanosilicates using an inexpensive inorganic precursor, ammonium titanyl sulfate (ATS or STA), (NH4)2TiO(SO4)2∙H2O. The latter is an intermediate in the processing of titanium-bearing concentrates produced from apatite-nepheline ores. In this paper, the new synthetic approach is exemplified by the microwave-assisted synthesis of IONSIVE-911, one of the most effective Cs-ion scavengers. The method can be modified to synthesize various titanosilicate compounds. [ABSTRACT FROM AUTHOR]

Published
2023
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