Igor Pekov

Lomonosov Moscow State University | MSU · Department of Mineralogy

The identification of the framework type in multilayer cancrinite- and sodalite-group minerals and synthetic compounds is predominantly based on the unit-cell dimensions determined from powder or single-crystal X-ray diffraction data, by analogy with previously characterized samples with known crystal structures. However, topological type of the fr...

Stillwellite, ideally CeBSiO5, is a rare mineral, however, its discovery stimulated the intense studies of a new class of stillwellite-like materials with remarkable electrical and optical properties. With the use of the modern non–ambient single crystal X-ray diffraction, this work sheds some light on the evolution of stillwellite crystal structur...

The new trioctahedral mica garmite, CsLiMg2(Si4O10)F2, a Cs analogue of tainiolite was found in an essentially quartz rock in the Darai-Piyoz alkaline massif, Rasht district (formerly Garm district), Central Tajikistan, and named after discovery locality. It is closely associated with Mn-bearing pectolite, aegirine, Sr-enriched fluorite, quartz, da...

The new sodalite-group mineral bolotinaite, ideally (Na 7 □)(Al 6 Si 6 O 24 )F⋅4H 2 O, was discovered in a volcanic ejectum of trachitoid sanidinite collected from the In den Dellen (Zieglowski) pumice quarry, Laach Lake (Laacher See) palaeovolcano, Eifel region, Rhineland-Palatinate, Germany. The associated minerals are sanidine, nepheline, annite...

Sodium plays an important role in the crystal structures of eudialyte-group minerals given that it can occupy different crystallographic sites. Predominantly, it distributes between the N(1–5) sites situated in the large cavities of the heteropolyhedral framework. Rarely, Na occupies split sites of the M(2) microregion where it can predominate over...

Hydronium (oxonium) cation H3O+ plays an important role in mineralogy and mineral structures. However, it is rather difficult to detect it using conventional methods of crystal structure analysis. In particular, hydronium-bearing eudialyte-group minerals (EGMs) are well known. In this paper, we provide data on a low-temperature X-ray structure anal...

This article displays data on cristobalite and tridymite from the Arsenatnaya active fumarole, the Tolbachik volcano, Kamchatka, Russia. The minerals occur in associations with fumarolic sylvite, sanidine, cassiterite, hematite, pseudobrookite, johillerite, tilasite, badalovite. Fumarolic cristobalite is tetragonal (-modification); the unit-cell pa...

The paper contains data on rutile, tripuhyite, and unusual Ti-rich cassiterite found in sublimates of active fumaroles at the Tolbachik volcano, Kamchatka, Russia. In contrast to rutile from other geological environments, fumarolic rutile is enriched in minor chalcophile elements. It contains up to (wt %): 35 Sb2O5, 59 SnO2, 11.3 TeO3, 1.9 CuO, 0.4...

Single crystals of “malakhovite” (an anthropogenic silico-oxide from burnt dumps of the Chelyabinsk coal basin; sp. gr. P , a = 10.555(4) Å, b = 10.928(3) Å, c = 9.059(3) Å, α = 106.338(12)°, β =95.87(7)°, γ = 124.40(2)°, V = 781.0(5) Å 3, Z = 1, R1 = 0.0378 have been investigated by electronprobe micro analysis, Raman spectroscopy, and X-ray diffr...

Ion-exchange properties of natural caryochroite (Na,Sr)3{(Fe,Mg)²⁺10(OH)6[TiO(Si6O17)(OH)0.5]2}·8H2O, a microporous heterophyllosilicate with a one-dimensional system of broad zeolytic channels, related to nafertisite Na3{Fe²⁺10(OH)6[TiO(Si6O17)F0.5]2}·2H2O, were studied in reactions with 1 N aqueous solutions of Rb, Cs, Ag, and Pb nitrates at 50 °...

The Lavrion area corresponds to the western part of the Attic-Cycladic metamorphic belt, in the back-arc region of the active Hellenic subduction zone. Between the Eocene and the Miocene, metamorphic rocks (mainly marbles and schists) underwent several stages of metamorphism and deformation due to collision and collapse of the Cycladic belt. Exhuma...

The new ettringite-group mineral chiyokoite, ideally Ca3Si(CO3)[B(OH)4]O(OH)5·12H2O, was found in a hydrothermally altered calc-silicate skarn at the Fuka mine, Okayama Prefecture, Japan. Associated minerals are calcite, henmilite, and tacharanite. Chiyokoite occurs as hexagonal prismatic crystals up to 30 μm long and up to 20 μm thick. The major f...

The new eudialyte-group mineral sergevanite, ideally Na15(Ca3Mn3)(Na2Fe)Zr3Si26O72(OH)3·H2O, was discovered in highly agpaitic foyaite from the Karnasurt Mountain, Lovozero alkaline massif, Kola Peninsula, Russia. The associated minerals are microcline, albite, nepheline, arfvedsonite, aegirine, lamprophyllite, fluorapatite, steenstrupine-(Ce), ilm...

The article describes a history of studies of samarskite-(Y), YFe3+Nb2O8, from its discovery in the Ilmeny Mountains (South Urals) in 1839 to the moment of the solution of its crystal structure and refnement of chemical formula in 2019.

A new niobium-rich lomonosovite variety with a high degree of ordering of Ti and Nb atoms has been investigated by X-ray diffraction analysis and electron probe microanalysis. Its simplified formula is Na 10 Ti 2 (Nb,Fe,Ti) 2 (Si 2 O 7) 2 (PO 4) 2 O 4. The triclinic unit-cell parameters are a = 5.411(1) Å, b = 7.108(1) Å, c = 14.477(2) Å, α = 99.78...

—We overview recent data on the mineralogy of oxidizing-type fumaroles of the Tolbachik Volcano (Kamchatka, Russia), with the main focus on the chemical specifics of the minerals. The active fumarole fields of Tolbachik are the most prominent mineral-forming exhalative system of this type in the world. About 350 mineral species, including 123 miner...

Polyoxometalate (POM) chemistry is an important avenue of comprehensive chemical research, due to the broad chemical, topological and structural variations of multinuclear polyoxoanions that result in advanced functionality of their derivatives. The majority of compounds in the polyoxometalate kingdom are synthesized under laboratory conditions. Ho...

Abstract — Hydrotalcite supergroup minerals stichtite, pyroaurite, iowaite, and woodallite form a complex solid-solution system at the Kyzyl-Uyuk locality (Terekta Ridge, Gorny Altai, Russia). The diversity of these minerals is due to: (1) subdivision by anionic interlayer composition into carbonate (stichtite and pyroaurite) and chloride (iowaite...

Dalnegorskite, a new pyroxenoid with the crystal chemical formula Ca2Ca2MnCa(Si3O9)2 and simplified formula Ca5Mn(Si3O9)2, is a rock-forming mineral in the B-bearing calcic skarns in the Dalnegorsk borosilicate deposit (Dalnegorsk, Primorsky Krai, Russia). It belongs to the bustamite structural type and forms a continuous solid-solution series with...

The crystal structure (R = 0.0750) of fiedlerite-1A Pb3Cl4F(OH) H2O from ancient slags of Lavrion (Greece) was studied on a single crystal. The mineral is triclinic, a = 8.5741(7), b = 8.0480(5), с = 7.2695(4) Å, (a = 90.087(5), (b = 102.126(6), (g = 103.424(6)) V = 476.37(6) Å3, Z = 2. Pb2+ cations centre bicapped trigonal prisms Pb(1)F(H2O)Cl6, P...

The crystal structure (R = 0.0750) of fiedlerite-1A Pb3Cl4F (OH) · H2O from ancient slags of Lavrion (Greece) was studied on a single crystal. The mineral is triclinic, a = 8.5741 (7) Å, b = 8.0480 (5) Å, c = 7.2695 (4) Å, α = 90.087 (5), β = 102.126 (6), γ = 103.424 (6)°, V = 476.37 (6) ų, Z = 2. The Pb²⁺ cations center the Pb(1)F(H2O)Cl6, Pb(2)(...

Rare metal-organic framework (MOF) minerals stepanovite and zhemchuzhnikovite can exhibit properties comparable to known oxalate MOF proton conductors, including high proton conductivity over a range of relative humidities at 25 oC, and retention of the framework structure upon thermal dehydration. They also have high thermodynamic stability, with...

Refined data on the crystal structure, chemical composition and properties of jouravskite, ideally Ca3Mn⁴⁺(SO4)(CO3)(OH)6·12H2O, have been obtained on a sample from N’Chwaning 3 Mine, Kuruman, Kalahari manganese field, Northern Cape Province, South Africa. The chemical composition determined using a combination of different methods (including ICP-O...

Dorrite, khesinite and rhönite from metamorphosed calcic xenoliths of the Bellerberg paleovolcano (Eifel, Germany) were studied, including first determination of the crystal structure of natural dorrite (R = 0.0636). Dorrite is triclinic, P-1, unit-cell parameters are: a = 10.4316(7), b = 10.8236(9), c = 8.9488(7) Å, α = 105.972(6), β = 96.003(9),...

The crystal chemical role of iron in Fe-rich pyroxenoids with bustamite-type structure was studied on five samples containing from 6.0 to 10.3 wt% FeO using electron microprobe, XRD crystal structure refinement and Mössbauer spectroscopy. The crystal chemical formulae are (Z = 1): M1(Mn0.85Fe²⁺0.15)2M2(Ca0.8Mn0.2)2M3(Fe2 +0.5Mn0.4(Mg,Al,Zn)0.1)M4Ca...

The crystal structure of manganonaujakasite was studied by single crystal X-ray analysis and infrared spectroscopy using a holotype sample with the empirical chemical formula (Na5.96Ca0.01) (Mn0.53Fe0.49)Al3.95Si8.03O26.00. The monoclinic unit cell parameters are: a = 15.029(1) Å b = 7.999(1) Å c = 10.467(1) Å β = 113.551(1)°; V = 1153.47(15) ų, s...

The crystal structures of two Cr-rich pumpellyite-group minerals, shuiskite with 22.6 wt% Cr2O3from the Biserskoe deposit and chromian pumpellyite-(Mg) with 16.4 wt% Cr2O3from the Glavnoe Saranovskoe deposit (both belong to the Saranovskaya group of chromite deposits, Middle Urals, Russia) were studied through single-crystal X-ray diffraction. The...

Amorphous post-mining matter with the simplified formula CuAl5(PO4,SiO4,SO4,AsO4)F(OH)11 – 13·nH2O (n = 5 – 6) was discovered in the West Caradon Mine, Liskeard District, Cornwall, England and characterized by means of electron microprobe analyses, direct determination of H2O, IR spectroscopy, powder X-ray diffraction and optical data. Origin of th...

The crystal structure of lemanskiite is determined for the first time (R = 0.019) and the mineral is redefined. Its chemical formula, crystal system, space group and unit-cell parameters are revised. The powder X-ray diffraction pattern of lemanskiite has been correctly indexed; the IR spectrum of an impurity-free sample has been obtained. It has b...

We demonstrate that rare metal-organic framework (MOF) minerals stepanovite and zhemchuzhnikovite can exhibit properties comparable to known oxalate MOFs, including high proton conductivity at 25 ^oC, and retention of the framework structure upon thermal dehydration. They also have high thermodynamic stability, with a pronounced stabilizi...

This paper is the first description of natural copper-rich oxide spinels. They were found in deposits of oxidizing-type fumaroles related to the Tolbachik volcano, Kamchatka, Russia. This mineralization is represented by nine species with the following maximum contents of CuO (wt.%, given in parentheses): a new mineral thermaerogenite, ideally CuAl...

The new mineral nöggerathite-(Ce) was discovered in a sanidinite volcanic ejectum from the Laach Lake (Laacher See) paleovolcano in the Eifel region, Rhineland-Palatinate, Germany. Associated minerals are sanidine, dark mica, magnetite, baddeleyite, nosean, and a chevkinite-group mineral. Nöggerathite-(Ce) has a color that ranges from brown to deep...

New arsenate minerals from the Arsenatnaya fumarole, Tolbachik volcano, Kamchatka, Russia. X. Edtollite, K2NaCu5Fe3+O2(AsO4)4, and alumoedtollite, K2NaCu5AlO2(AsO4)4 - Igor V. Pekov, Natalia V. Zubkova, Atali A. Agakhanov, Dmitry A. Ksenofontov, Leonid A. Pautov, Evgeny G. Sidorov, Sergey N. Britvin, Marina F. Vigasina, Dmitry Y. Pushcharovsky

A new mineral species zincovelesite-6N6S with the simplified formula Zn3(Fe³⁺,Mn³⁺,Al,Ti)8O15(OH) was discovered in the orogenetic zone related to the “Mixed Series” metamorphic complex near the Nežilovo village, Jacupica Mountains, Pelagonia mountain range, Republic of Macedonia. In oxide Zn-Fe-Mn ore, zincovelesite-6N6S forms lenticular aggregate...

The new mineral calamaite, Na2TiO(SO4)2 · 2H2O, was found in the oxidation zone of a pyrite orebody at the abandoned Alcaparrosa sulfate mine, Calama commune, El Loa province, Antofagasta region, Chile. It is associated with römerite, coquimbite, metavoltine, tamarugite, halotrichite, szomolnokite, rhomboclase, and ferricopiapite. Calamaite forms a...

Kurchatovite and clinokurchatovite, both of ideal composition CaMgB2O5, from the type localities (Solongo, Buryatia, Russia, and Sayak-IV, Kazakhstan, respectively) have been studied using electron microprobe and single-crystal X-ray diffraction methods. The empirical formulae of the samples are Ca1.01Mg0.87Mn0.11Fe2+0.02B1.99O5 and Ca0.94Mg0.91Fe2...

Hydrotalcite, ideally [Mg6Al2(OH)16 ](CO3)(H2O)4 , was studied in samples from Dypingdal, Snarum, Norway (3R and 2H), Zelentsovskaya pit (2H) and Praskovie-Evgenievskaya pit (2H) (both Southern Urals, Russia), Talnakh, Siberia, Russia (3R), Khibiny, Kola, Russia (3R), and St. Lawrence, New York, USA (3R and 2H). Two polytypes, 3R and 2H (both "clas...

New arsenate minerals from the Arsenatnaya fumarole, Tolbachik volcano, Kamchatka, Russia. IX. Arsenatrotitanite, NaTiO(AsO4) - Igor V. Pekov, Natalia V. Zubkova, Atali A. Agakhanov, Dmitry I. Belakovskiy, Marina F. Vigasina, Vasiliy O. Yapaskurt, Evgeny G. Sidorov, Sergey N. Britvin, Dmitry Y. Pushcharovsky

The crystal structures of four betalomonosovite samples from peralkaline pegmatites of the Khibiny alkaline complex, Kola Peninsula, Russia, were studied using single-crystal X-ray diffraction. The samples represent different chemical and structural varieties of betalomonosovite. The suggested general formula of betalomonosovite, based on the empir...

The new mineral ziminaite, ideally Fe³⁺VO4, was found in fumarole sublimates at the Bezymyannyi volcano, Kamchatka, Russia. Ziminaite occurs as lamellar, tabular or flattened prismatic crystals up to 10 × 30 × 50 μm typically epitaxially overgrowing koksharovite, and as aggregates (up to 0.15 mm) associated with bannermanite in cavities in volcanic...

The new zeolite martinandresite, ideally Ba2(Al4Si12O32)·10H2O, was discovered in the armenite locality of Wasenalp near the Isenwegg peak, Ganter valley, Simplon region, Switzerland. The associated minerals are armenite, quartz, dickite, and chlorite. Martinandresite forms tan-coloured blocky crystals up to 8 × 5 × 3.5 mm, their aggregates up to 6...

The new mineral triazolite is found in a guano deposit located on the Pabellón de Pica Mountain, Iquique Province, Tarapacá Region, Chile. Associated minerals are salammoniac, halite, dittmarite, joanneumite, chanabayaite, nitratine, natroxalate and möhnite. Triazolite occurs as deep blue prismatic crystals up to 0.1 mm × 0.15 mm × 0.75 mm and thei...

The high-temperature behaviour of three Ca borosilicates has been studied by in situ powder high-temperature X-ray diffraction (HTXRD), differential scanning calorimetry and thermogravimetry in the temperature range 30–900 °C for natural samples of datolite, CaBSiO4(OH), and ‘bakerite’, Ca4B5Si3O15(OH)5, and a synthetic analogue of okayamalite, Ca2...

This paper is a review devoted to a special type of arsenic mineralization related to volcanic fumaroles of the oxidizing type. Fifty-four hydrogen-free arsenates (40 valid species and 14 insufficiently characterized phases) with Cu2+, Mg, Al, Fe3+, Ti4+, Zn, Ca, Na, and K are identified here and 46 of them are endemics of fumarolic formation. Fift...

The new mineral genplesite, Ca3 Sn(SO4)2 (OH)6 · 3H2 O, the first natural tin sulfate, is found in cavities in massive chalcopyrite ore at the Oktyabr'skoe Cu-Ni-Pd-Pt deposit (Oktyabr'sky mine), Talnakh, Norilsk district, Siberia, Russia. It is a latestage hydrothermal mineral associated with greenalite, chamosite, pectolite, ferroactinolite, calc...