Tolbachik Volcano Research Articles

Unusual silicate mineralization in fumarolic sublimates of the Tolbachik volcano, Kamchatka, Russia – Part 1: Neso-, cyclo-, ino- and phyllosilicates

Abstract. This is the initial paper in a pair of articles devoted to silicate minerals from fumaroles of the Tolbachik volcano (Kamchatka, Russia). These papers contain the first systematic data on silicate mineralization of fumarolic genesis. In this article nesosilicates (forsterite, andradite and titanite), cyclosilicate (a Cu,Zn-rich analogue of roedderite), inosilicates (enstatite, clinoenstatite, diopside, aegirine, aegirine-augite, esseneite, “Cu,Mg-pyroxene”, wollastonite, potassic-fluoro-magnesio-arfvedsonite, potassic-fluoro-richterite and litidionite) and phyllosilicates (fluorophlogopite, yanzhuminite, “fluoreastonite” and the Sn analogue of dalyite) are characterized with a focus on chemistry, crystal-chemical features and occurrence. Unusual As5+-rich varieties of forsterite, andradite, titanite, pyroxenes, amphiboles and mica are described. General data on silicate-bearing active fumaroles and the diversity and distribution of silicates in fumarole deposits are reported. Evidence for the fumarolic origin of silicate mineralization is discussed.

Unusual silicate mineralization in fumarolic sublimates of the Tolbachik volcano, Kamchatka, Russia – Part 2: Tectosilicates

Abstract. This second of two companion articles devoted to silicate mineralization in fumaroles of the Tolbachik volcano (Kamchatka, Russia) reports data on chemistry, crystal chemistry and occurrence of tectosilicates: sanidine, anorthoclase, ferrisanidine, albite, anorthite, barium feldspar, leucite, nepheline, kalsilite, sodalite and hauyne. Chemical and genetic features of fumarolic silicates are also summarized and discussed. These minerals are typically enriched with “ore” elements (As, Cu, Zn, Sn, Mo, W). Significant admixture of As5+ (up to 36 wt % As2O5 in sanidine) substituting Si is the most characteristic. Hauyne contains up to 4.2 wt % MoO3 and up to 1.7 wt % WO3. All studied silicates are hydrogen-free, including mica and amphiboles which are F-rich. Iron-bearing minerals contain only Fe3+ due to strongly oxidizing formation conditions. In Tolbachik fumaroles, silicates were formed in the temperature range 500–800 ∘C as a result of direct deposition from the gas phase (as volcanic sublimates) or gas–rock interactions. The zonation in distribution of major silicate minerals observed in a vertical section of the Arsenatnaya fumarole, from deep (the hottest) to upper parts is diopside + forsterite + enstatite + andradite → diopside → fluorophlogopite + diopside → sanidine + fluorophlogopite → sanidine. This is in agreement with volatilities of major species-defining metals in volcanic gases. From a crystal-chemical viewpoint, this series corresponds to the following sequence of crystallization of minerals with temperature decrease: nesosilicates → inosilicates → phyllosilicates → tectosilicates.

Oxidizing-Type Fumaroles of the Tolbachik Volcano, a Mineralogical and Geochemical Unique

Abstract —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 minerals first discovered here, are reliably identified in the Tolbachik fumaroles. The species diversity and the specifics of this mineralization are due to the unique combination of the physicochemical conditions and mechanisms of its formation: high temperatures, atmospheric pressure, superhigh oxygen fugacity, gas transport of most of chemical elements, and direct deposition of many high-temperature minerals from volcanic gases with a specific geochemical composition, including strong enrichment in alkaline metals and chalcophile (“ore”) elements. Sublimate silicates and minerals of As, Cu, Zn, Mn, Ti, Sn, Sb, Se, Au, Ag, Cs, Tl, and F are briefly described in terms of mineral geochemistry.

A New Mineral Ferrisanidine, K[Fe3+Si3O8], the First Natural Feldspar with Species-Defining Iron

Ferrisanidine, K[Fe3+Si3O8], the first natural feldspar with species-defining iron, is an analogue of sanidine bearing Fe3+ instead of Al. It was found in exhalations of the active Arsenatnaya fumarole at the Second scoria cone of the Northern Breakthrough of the Great Fissure Tolbachik Eruption, Tolbachik volcano, Kamchatka Peninsula, Russia. The associated minerals are aegirine, cassiterite, hematite, sylvite, halite, johillerite, arsmirandite, axelite, aphthitalite. Ferrisanidine forms porous crusts composed by cavernous short prismatic crystals or irregular grains up to 10 μm × 20 μm. Ferrisanidine is transparent, colorless to white, the lustre is vitreous. Dcalc is 2.722 g·cm−3. The chemical composition of ferrisanidine (wt. %, electron microprobe) is: Na2O 0.25, K2O 15.15, Al2O3 0.27, Fe2O3 24.92, SiO2 60.50, in total 101.09. The empirical formula calculated based on 8 O apfu is (K0.97Na0.03)Ʃ1.00(Si3.03Fe3+0.94Al0.02)Ʃ3.99O8. The crystal structure of ferrisanidine was studied using the Rietveld method, the final R indices are: Rp = 0.0053, Rwp = 0.0075, R1 = 0.0536. Parameters of the monoclinic unit cell are: a = 8.678(4), b = 13.144(8), c = 7.337(5) Å, β = 116.39(8)°, V = 749.6(9) Å3. Space group is C2/m. The crystal structure of ferrisanidine is based on the sanidine-type “ferrisilicate” framework formed by disordered [SiO4] and [Fe3+O4] tetrahedra.

Arsenic and phosphorus in feldspar framework: sanidine–filatovite solid solution series from fumarolic exhalations of the Tolbachik volcano, Kamchatka, Russia

The influence of pentavalent arsenic and phosphorus on crystal chemical features of the feldspar framework was studied on the minerals belonging to the sanidine–filatovite solid-solution series from fumarolic exhalations of the Tolbachik volcano (Kamchatka, Russia). The reported feldspars demonstrate the first example of natural continuous solid solution between silicate and arsenate. The content of As2O5 varies from 0.0 to 45 wt% along with the highest phosphorus content found in natural feldspars: up to 5 wt% P2O5. The major substitution schemes in the studied feldspars are Al3+ + M5+ → 2Si4+ and M2+ + M5+ → Al3+ + Si4+, where M2+ = Zn and Cu and M5+ = As and P. The crystal structures of four samples with empirical formulae K0.95[(Si2.98Al0.93Fe0.08As0.02)Ʃ4.01O8] (space group C2/m), (K0.91Na0.06Ca0.03)Ʃ1.00[(Si2.81Al1.14As0.03P0.03Fe0.01)Ʃ4.02O8] (C2/m), K0.82[(Al1.92As1.11Si0.89Zn0.05Fe0.03Cu0.02P0.01)Ʃ4.03O8] (I2/c), K0.99[(Si1.87Al1.51As0.53P0.05Fe0.02Cu0.01)Ʃ3.99O8] (I2/c) were studied. The phase transition in the sanidine–filatovite solid-solution series is C2/m → I2/c. This is caused by the change of the Al:(Si + As) ratio from 1:3 in sanidine to 1:1 in filatovite along with significant ordering of Al, Si and As in the framework.

Alkali sulfates with aphthitalite-like structures from fumaroles of the Tolbachik Volcano, Kamchatka, Russia. I. MetathÉnardite, a natural high-temperature modification of Na2SO4

Abstract A new mineral, metathénardite, ideally Na2SO4, the high-temperature hexagonal dimorph of thénardite, a natural analogue of the synthetic phase Na2SO4(I), was found in the sublimates of active fumaroles at the Second scoria cone of the Northern Breakthrough of the Great Tolbachik Fissure eruption, Tolbachik volcano, Kamchatka, Russia. The holotype originates from the Glavnaya Tenoritovaya fumarole in which metathénardite is associated with hematite, tenorite, fluorophlogopite, sanidine, anhydrite, krasheninnikovite, vanthoffite, glauberite, johillerite, and lammerite. The cotypes 1 and 2 are from the Arsenarnaya (with hematite, tenorite, fluorophlogopite, sanidine, euchlorine, wulffite, anhydrite, fluoborite, johillerite, nickenichite, calciojohillerite, badalovite, tilasite, cassiterite, and pseudobrookite) and the Yadovitaya (with tenorite, euchlorine, fedotovite, dolerophanite, langbeinite, krasheninnikovite, anhydrite, and hematite) fumaroles, respectively. All specimens with metathénardite were collected from areas with temperatures of 350–400 °C. Metathénardite forms hexagonal tabular, lamellar, or dipyramidal crystals (forms: {001}, {100}, {102}, and {201}) up to 3 mm combined in crusts up to several hundred cm2 in area. The mineral is transparent to semitransparent, colorless, white, light-blue, greenish, yellowish, grayish or brownish, with vitreous luster. Dmeas. = 2.72(1), Dcalc. = 2.717 g/cm3. Metathénardite is optically uniaxial (–), ω = 1.489(2), ε = 1.486(2). The empirical formulae are (Na1.92K0.05Ca0.02Zn0.01)[S0.99O4] (holotype), (Na1.54K0.22Ca0.09Cu0.01Mg0.01)[S1.00O4] (cotype 1), and Na1.65K0.11Ca0.05Cu0.04Mg0.01)[S1.01O4] (cotype 2). Admixed K and bivalent cations probably stabilize the hexagonal aphthitalite-like structure of metathénardite at room temperature. The crystal structure was solved using single crystals of all three samples, R1 = 0.0852, 0.0452, and 0.0449 for holotype and cotypes 1 and 2, respectively. The space group is P63/mmc, and the unit-cell parameters of the holotype are a = 5.3467(9), c = 7.0876(16) Å, V = 157.47(6) Å3, and Z = 2. The strongest reflections of the powder X-ray diffraction pattern [d,Å(I)(hkl)] are: 4.667(27)(100), 3.904(89)(101), 3.565(33)(002), 2.824(94)(102), 2.686(100)(110), and 1.939(35)(202). Metathénardite and thénardite clearly differ from one another in X-ray diffraction data and infrared and Raman spectra.

Koryakite, NaKMg2Al2(SO4)6, a new NASICON-related anhydrous sulfate mineral from Tolbachik volcano, Kamchatka, Russia

AbstractExhalative mineral assemblages from fumaroles of Tolbachik volcano are very rich in anhydrous sulfate minerals of alkali and transition metals. Koryakite, ideally NaKMg2Al2(SO4)6, was found in the Yadovitaya fumarole of the Second scoria cone of the North Breach of the Great Tolbachik Fissure Eruption (1975–1976), Tolbachik volcano, Kamchatka Peninsula, Russia. Koryakite occurs as a product of fumarolic activity and closely associates with euchlorine and langbeinite. Koryakite is trigonal, R$\bar{3}$, a = 8.1124(11), c = 22.704(7) Å and V = 1294.0(5) Å3. The chemical composition determined by electron-microprobe analysis is (wt.%): Na2O 4.27, K2O 5.85, ZnO 0.31, СaO 0.31, CuO 0.76, MgO 10.15, Al2O3 11.47, Fe2O3 2.73, SO3 64.33 and SiO2 0.13, total 100.31. The empirical formula calculated on the basis of 24 O apfu is Na1.03K0.93(Mg1.89Cu0.07Ca0.04Zn0.03)Σ2.03(Al1.68Fe3+0.26)Σ1.94(S6.02Si0.02)Σ6.04O24. No natural or synthetic chemical analogues of koryakite are known to date. The topology of the [M2+2M3+2(SO4)6]2– heteropolyhedral framework in koryakite is very similar to the one in millosevichite, Al2(SO4)3 and mikasaite, Fe3+2(SO4)3. Replacement of part of the trivalent cations in the [M3+2(SO4)3]0 framework by divalent cations gives the framework a negative charge for koryakite and allows the incorporation of the alkali species in the channels. This structural mechanism is reminiscent of the concept of stuffed derivative structures. Koryakite is also structurally related to synthetic NaMgFe3+(SO4)3 and to the broader family of NASICON-related phases.

Majzlanite, K2Na(ZnNa)Ca(SO4)4, a new anhydrous sulfate mineral with complex cation substitutions from Tolbachik volcano

AbstractA new mineral majzlanite, ideally K2Na(ZnNa)Ca(SO4)4, was found in high-temperature exhalative mineral assemblages in the Yadovitaya fumarole, Second scoria cone of the Great Tolbachik Fissure Eruption (1975–1976), Tolbachik volcano, Kamchatka Peninsula, Russia. Majzlanite is associated closely with langbeinite and K-bearing thénardite. Majzlanite is grey with a bluish tint, has a white streak and vitreous lustre. The mineral is soluble in warm water. Majzlanite is monoclinic,C2/c,a= 16.007(2),b= 9.5239(11),c= 9.1182(10) Å, β = 94.828(7)°,V= 1385.2(3) Å3andZ= 16. The eight strongest lines of the X-ray powder diffraction pattern are [d, Å (I, %)(hkl)]: 3.3721(40)($\bar{3}$12), 3.1473(56)($\bar{4}$02), 3.1062(65)($\bar{2}$22), 2.9495(50)($\bar{1}$31), 2.8736(100)($\bar{1}$13), 2.8350(70)(421), 2.8031(45)(511) and 2.6162(41)($\bar{5}$12). The following structural formula was obtained: K2Na(Zn0.88Na0.60Cu0.36Mg0.16)(Ca0.76Na0.24)(S0.98Al0.015Si0.005O4)4. The chemical composition determined by electron-microprobe analysis is (wt.%): Na2O 9.73, K2O 15.27, ZnO 11.20, CaO 7.03, CuO 4.26, MgO 1.07, Al2O30.47, SO351.34, SiO20.12, total 100.49. The empirical formula calculated on the basis of 16 O apfu is K1.99Na1.93Zn0.84Ca0.77Cu0.33Mg0.16(S3.94Al0.06Si0.01)O16and the simplified formula is K2Na(Zn,Na,Cu,Mg)Σ2(Ca,Na)(SO4)4. No natural or synthetic compounds directly chemically and/or structurally related to majzlanite are known to date. The topology of the heteropolyhedral framework in majzlanite is complex. An interesting feature of the structure of majzlanite is an edge-sharing of ZnO6octahedra with SO4tetrahedra.

High‐temperature gold‐copper extraction with chloride flux in lava tubes of Tolbachik volcano (Kamchatka)

AbstractSubvolcanic environments in supra‐subduction zones are renowned for hosting epithermal deposits that often contain electrum and native gold, including bonanza examples. This study examined mineral assemblages and processes occurring in shallow‐crust volcanic settings using recent eruption (2012–2013) of the basaltic Tolbachik volcano in the Kamchatka arc. The Tolbachik eruptive system is characterized by an extensive system of lava tubes. After cessation of magma input, the tubes maintained the flow of hot oxidized gases that episodically interacted with the lava surfaces and sulphate‐chloride precipitates from volcanic gases on these surfaces. The gas‐rock interaction had strong pyrometamorphic effects that resulted in the formation of molten salt, oxidized (tenorite, hematite, Cu‐rich magnesioferrite) and skarn‐like silicate mineral assemblages. By analogy with experimental studies, we propose that a combination of these processes was responsible for extraction of metals from the basaltic wall rocks and deposition of Cu‐, Fe‐ and Cu‐Fe‐oxides and native gold.

New arsenate minerals from the Arsenatnaya fumarole, Tolbachik volcano, Kamchatka, Russia. XIII. Pansnerite, K3Na3Fe3+6(AsO4)8

AbstractThe new mineral pansnerite, ideally K3Na3Fe3+6(AsO4)8, was found in the Arsenatnaya fumarole at the Second scoria cone of the Northern Breakthrough of the Great Tolbachik Fissure Eruption, Tolbachik volcano, Kamchatka, Russia. It is associated with aphthitalite, hematite, sanidine, badalovite, khrenovite, achyrophanite, arsenatrotitanite, ozerovaite, tilasite, calciojohillerite, johillerite, nickenichite, svabite, katiarsite, yurmarinite, anhydrite, rutile, cassiterite and pseudobrookite. Pansnerite forms tabular to lamellar (flattened on {010}), usually pseudo-hexagonal crystals up to 0.2 mm × 0.7 mm × 1 mm and crystal clusters up to 2 mm across. It is transparent to translucent, light green, pale greenish, yellowish–greenish or yellowish, with vitreous lustre. The mineral is brittle, with perfect {010} cleavage. The Mohs’ hardness is ca 3. Dcalc is 3.596 g cm–3. Pansnerite is optically biaxial (–), α = 1.702(4), β = 1.713(4), γ = 1.717(4), 2Vmeas = 45(10)° and 2Vcalc = 62°. Chemical composition (holotype, wt.%, electron microprobe data) is: Na2O 6.39, K2O 8.52, CaO 0.08, MgO 0.08, MnO 0.02, NiO 0.02, CuO 1.35, ZnO 0.34, Al2O3 7.35, Cr2O3 0.04, Fe2O3 16.72, SiO2 0.16, P2O5 0.22, V2O5 0.09, As2O5 57.76, SO3 0.04, total 99.20. The empirical formula based on 32 O apfu is K2.86Na3.26Ca0.02(Fe3+3.31Al2.28Cu0.27Zn0.07Mg0.03Cr0.01)Σ5.97(As7.95P0.05Si0.04V0.02S0.01)Σ8.06O32. Pansnerite is orthorhombic, Cmce, a = 10.7372(3), b = 20.8367(8), c = 6.47335(15) Å, V = 1448.27(7) Å3 and Z = 2. The strongest reflections of the X-ray powder diffraction pattern [d,Å(I)(hkl)] are: 10.49(100)(020), 5.380(88)(111), 4.793(65)(220), 3.105(46)(311, 002), 3.079(32)(112, 061), 2.932(35)(260), 2.783(65)(202) and 2.694(52)(400, 222). The crystal structure was solved from single-crystal X-ray diffraction data, R1 = 2.82%. The structure is based on heteropolyhedral layers formed by MO6 octahedra (M = Fe3+ and Al) sharing common vertices and connected by AsO4 tetrahedra. Na+ and K+ cations are located in the interlayer space. The mineral is named in honour of the German–Russian mineralogist and geographer Lavrentiy Ivanovich Pansner (1777–1851). Pansnerite forms a solid-solution series with the isotypic mineral ozerovaite, ideally KNa2Al3(AsO4)4.

Faunal notes on the Bumblebee genus Bombus Latreille, 1802 in the vicinity of the Tolbachik Volcano (Kamchatka Krai, Russia)

Nine species of Bombus from seven subgenera (Alpinobombus, Bombus, Melanobombus, Mendacibombus, Psithyrus, Pyrobombus, and Thoracobombus) were collected in three sites in 2008 in the vicinity of the Tolbachik volcano (between two large eruptions in 1975–1976 and 2012–2013), representing 41% of the entire Kamchatka Krai's fauna of Bombus species. The trophic links of the discovered Bombus species with the plants of the Asteraceae and Onagraceae families are characteristic of slag fields.

Natural forsterite strongly enriched by arsenic and phosphorus: chemistry, crystal structure, crystal morphology and zonation

Unusual variety of forsterite strongly enriched by pentavalent constituents, phosphorus and arsenic (up to 12.9 wt% P2O5 and up to 16.0 wt% As2O5) was found in sublimates of the Arsenatnaya fumarole, Tolbachik volcano, Kamchatka, Russia, in association with As- and P-depleted forsterite, anhydrite, diopside, hematite, spinel, hauyne, fluorapatite, svabite, berzeliite, calciojohillerite, and arsenudinaite. This forsterite is the P-richest natural olivine which also demonstrates first case of As incorporation in an olivine-type silicate. P- and As-rich forsterite is orthorhombic, space group Pbnm, unit-cell parameters are: a = 4.7762(2), b =10.2643(4), c = 5.9646(2) A and V = 292.41(2) A3. Its crystal structure was solved on single crystal and refined to R = 2.88%. The crystal chemical formula is M(1)(Mg0.83[vac]0.17)M(2)(Mg0.95[vac]0.05)[Si0.56P0.32As0.12]O4. The substitution scheme for the incorporation of pentavalent constituents in forsterite is: VIMg2+ + 2IVSi4+ ↔ VI[vac]0 + 2IVT5+, in which T5+ = P, As and [vac] = vacancy. No sign of vacancies in the tetrahedrally coordinated T site is found.

Dokuchaevite, Cu8O2(VO4)3Cl3, a new mineral with remarkably diverse Cu2+ mixed-ligand coordination environments

AbstractDokuchaevite, ideally Cu8O2(VO4)3Cl3, was found in the Yadovitaya fumarole of the Second scoria cone of the North Breach of the Great Tolbachik Fissure Eruption (1975–1976), Tolbachik volcano, Kamchatka Peninsula, Russia. Dokuchaevite occurs on the crusts of various copper sulfate exhalative minerals (such as kamchatkite and euchlorine) as individual prismatic crystals. Dokuchaevite is triclinic, P$\bar{1}$, a = 6.332(3), b = 8.204(4), c = 15.562(8) Å, α = 90.498(8), β = 97.173(7), γ = 90.896(13)°, V = 801.9(7) Å3 and R1 = 0.057. The eight strongest lines of the X-ray powder diffraction pattern are (d, Å (I)(hkl): (15.4396)(18)(00$\bar{1}$), (7.2762)(27)(0$\bar{1}$1), (5.5957)(43)(012), (4.8571)(33)($\bar{1}\bar{1}$1), (3.1929) (29)(023), (2.7915)(30)(202), (2.5645)(21)(032), (2.5220)(100)(1$\bar{3}$0), (2.4906)(18)(130) and (2.3267)(71)(2$\bar{2}$2). The chemical composition determined by electron-microprobe analysis is (wt.%): CuO 60.87, ZnO 0.50, FeO 0.36, V2O5 19.85, As2O5 6.96, SO3 0.44, MoO3 1.41, SiO2 0.20, P2O5 0.22, Cl 10.66, –O = Cl2 2.41, total 99.06. The empirical formula calculated on the basis of 17 anions per formula unit is (Cu7.72Zn0.06Fe0.05)Σ7.83(V2.20As0.61Mo0.10S0.06P0.03Si0.03)Σ3.03O13.96Cl3.04.The crystal structure of dokuchaevite represents a new structure type with eight Cu sites, which demonstrate the remarkable diversity of Cu2+ mixed-ligand coordination environments. The crystal structure of dokuchaevite is based on OCu4 tetrahedra that share common corners thus forming [O2Cu6]8+ single chains. Two of the eight symmetrically independent copper atoms do not form Cu–O bonds with additional oxygen atoms, and thus are not part of the OCu4 tetrahedra, but provide the three-dimensional integrity of the [O2Cu6]8+ chains into a framework. TO4 mixed tetrahedral groups are located within the cavities of the framework. The structural formula of dokuchaevite can be represented as Cu2[Cu6O2](VO4)3Cl3.

New arsenate minerals from the Arsenatnaya fumarole, Tolbachik volcano, Kamchatka, Russia. XII. Zubkovaite, Ca3Cu3(AsO4)4

AbstractThe new mineral zubkovaite, Ca3Cu3(AsO4)4, was found in the Arsenatnaya fumarole at the Second scoria cone of the Northern Breakthrough of the Great Tolbachik Fissure Eruption, Tolbachik volcano, Kamchatka, Russia. It is associated with anhydrite, svabite, hematite, johillerite, tilasite, fluorophlogopite, sanidine and aphthitalite. Zubkovaite occurs as coarse prismatic crystals up to 0.01 mm × 0.01 mm × 0.2 mm combined in radiating aggregates or crusts. The mineral is transparent, bright sky-blue, turquoise-coloured or light bluish-green, with vitreous lustre. It is brittle, with imperfect cleavage. The Mohs’ hardness isca3.Dcalcis 4.161 g cm–3. Zubkovaite is optically biaxial (–), α = 1.747(5), β = 1.774(5), γ = 1.792(5) and 2Vmeas= 75(10)°. Chemical composition (wt.%, electron microprobe) is: CaO 19.22, CuO 27.37, As2O552.54, SO30.67, total 99.80. The empirical formula based on 16 O apfu is Ca2.96Cu2.97(As3.945S0.07)Σ4.015O16. Zubkovaite is monoclinic,C2,a= 16.836(3),b= 5.0405(8),c= 9.1173(17) Å, β = 117.388(13)°,V= 687.0(2) Å3andZ= 2. The strongest reflections of the powder XRD pattern [d,Å (I) (hkl)] are: 7.44 (100) ($\bar 2$01), 3.727 (79) (400,$\bar 2$02,$\bar 3$11), 3.334 (92) ($\bar 1$12), 2.914 (73) (311), 2.765 (50) ($\bar 6$01,$\bar 6$02), 2.591 (96) ($\bar 3$13) and 2.521 (53) (020). The crystal structure is unique for minerals. It was solved from single-crystal X-ray diffraction data toR= 7.19%. The structure contains trimers of Cu2+-centred polyhedra (consisting of one distorted square CuO4in the core and two distorted square pyramids CuO5) and two crystallographically independent As5+O4tetrahedra playing different roles: As(2)O4tetrahedra link neighbouring trimers into ribbons whereas As(1)O4tetrahedra link adjacent ribbons into heteropolyhedral layers; Ca cations are located in the interlayer space. The mineral is named in honour of the Russian crystallographer and crystal chemist Natalia Vital'evna Zubkova (born 1976).

Comparison of enigmatic diamonds from the Tolbachik arc volcano (Kamchatka) and Tibetan ophiolites: Assessing the role of contamination by synthetic materials

The enigmatic appearance of cuboctahedral diamonds in ophiolitic and arc volcanic rocks with morphology and infrared characteristics similar to synthetic diamonds that were grown from metal solvent requires a critical reappraisal. We have studied 15 diamond crystals and fragments from Tolbachik volcano lava flows, using Fourier transform infrared spectrometry (FTIR), transmission electron microscopy (TEM), synchrotron X-ray fluorescence (SRXRF) and laser ablation inductively coupled plasma mass-spectrometry (LA-ICP-MS). FTIR spectra of Tolbachik diamonds correspond to typical type Ib patterns of synthetic diamonds. In TEM films prepared using focused ion beam technique, we find Mn-Ni and Mn-Si inclusions in Tolbachik diamonds. SRXRF spectra indicate the presence of Fe-Ni and Fe-Ni-Mn inclusions with Cr, Ti, Cu, and Zn impurities. LA-ICP-MS data show variable but significantly elevated concentrations of Mn, Fe, Ni, and Cu reaching up to 70 ppm. These transition metal concentration levels are comparable with those determined by LA-ICP-MS for similar diamonds from Tibetan ophiolites. Mn-Ni (+Fe) solvent was widely used to produce industrial synthetic diamonds in the former USSR and Russia with very similar proportions of these metals. Hence, it appears highly probable that the cuboctahedral diamonds recovered from Kamchatka arc volcanic rocks represent contamination and are likely derived from drilling tools or other hard instruments. Kinetic data on diamond dissolution in basaltic magma or in fluid phase demonstrate that diamond does not form under the pressures and temperature conditions prevalent within the magmatic system beneath the modern-day Klyuchevskoy group of arc volcanoes. We also considered reference data for inclusions in ophiolitic diamonds and compared them with the composition of solvent used in industrial diamond synthesis in China. The similar inclusion chemistry close to Ni70Mn25Co5 for ophiolitic and synthetic Chinese diamonds scrutinized here suggests that most diamonds recovered from Tibetan and other ophiolites are not natural but instead have a synthetic origin. In order to mitigate further dubious reports of diamonds from unconventional tectonic settings and source rocks, we propose a set of discrimination criteria to better distinguish natural cuboctahedral diamonds from those produced synthetically in industrial environments and found as contaminants in mantle- and crust-derived rocks.

Antofagastaite, Na2Ca(SO4)2·1.5H2O, a new mineral related to syngenite

AbstractThe new mineral antofagastaite, ideally Na2Ca(SO4)2·1.5H2O, was found in the oxidation zone of sulfide–quartz veins at the abandoned Coronel Manuel Rodríguez mine, Mejillones, Antofagasta Province, Antofagasta Region, Chile. It is associated with sideronatrite, metasideronatrite, aubertite, gypsum, ferrinatrite, glauberite, amarillite and an unidentified Fe phosphate. Antofagastaite occurs as prismatic crystals up to 0.5 mm × 1 mm × 5 mm, elongated along [010], typically combined in open-work aggregates up to 1 cm across. Antofagastaite is transparent and colourless, with vitreous lustre. It is brittle; the Mohs’ hardness isca3. Cleavage is distinct on (001).Dmeas.is 2.42(1) andDcalc.is 2.465 g cm−3. Antofagastaite is optically biaxial (–), α = 1.489(2), β = 1.508(2), γ = 1.510(2) and 2Vmeas.= 40(10)°. The IR spectrum is reported. Chemical composition (wt.%, electron microprobe, H2O determined by gas chromatography) is: Na2O 20.85, CaO 17.42, SO352.56, H2O 7.93, total 98.76. The empirical formula (based on 8 O atoms belonging to sulfate anions per formula unit with all H belonging to H2O molecules) is Na2.06Ca0.95S2.01O8·1.35H2O. Antofagastaite is monoclinic,P21/m,a= 6.4596(4),b= 6.8703(5),c= 9.4685(7) Å, β = 104.580(4)°,V= 406.67(5) Å3andZ= 2. The strongest reflections of the powder XRD pattern [d, Å (I, %) (hkl)] are: 9.17 (100) (001), 5.501 (57) (011), 3.437 (59) (020), 3.058 (43) (003), 2.918 (50) (2¯11), 2.795 (35) (013) and 2.753 (50) (121, 201). The crystal structure was solved based on single-crystal X-ray diffraction data,R1= 5.71%. The structure of antofagastaite consists of ordered and disordered blocks and is related to syngenite K2Ca(SO4)2·H2O. Incorporation of additional H2O molecules in the syngenite-type structure results in disorder of the one of the two tetrahedral sulfate groups occurring in antofagastaite. In addition to the above-reported type material, antofagastaite together with syngenite and blödite occurs in the Arsenatnaya fumarole, Tolbachik volcano, Kamchatka, Russia.

The influence of emissivity on the thermo-rheological modeling of the channelized lava flows at Tolbachik volcano

The application of thermo-rheological models to forecast active lava flow emplacement and quantify the eruptive parameters of older flow-producing eruptions has become a somewhat common tool over the last decade. With the modification and adaption of these models to modular computing languages, they are now easier, quicker, and being incorporated into studies of both terrestrial and planetary volcanism. These models, such as FLOWGO, rely on numerous assumptions and input parameters, some of which such as radiant emissivity are not well understood for molten materials. Without a well-grounded knowledge of how this parameter governs radiant cooling, physics-based estimates of temperature and models such as FLOWGO that track cooling with time will be in error. Here, we perform a detailed FLOWGO-based modeling study of lava flows emplaced at Tolbachik volcano during the 2012-2013 and the 1975-1976 eruptions. Specifically, we have modified the FLOWGO model to incorporate a two-component emissivity model linked to the fraction of molten lava and cooled crust. We focus first on the large Leningradskoye Flow emplaced at the start of the 2012 eruption, relying on data from numerous other orbital sensors including MODIS, ASTER and ALI to constrain some of the model input parameters. The two-component emissivity adaption produced better fits to the final flow length and was found to be most significant for flows with lower percentages of initial crust cover. We then applied these results and model constraints to the large Cone II flow formed in 1975, for which no satellite-based constraining data are available. By knowing the final flow dimensions coupled with the constraints determined from the previous modeling, we were able to estimate an effusion rate (700 m 3 /s), initial velocity (1.5 to 2 m/s) and final viscosity (10 8 Pa·s). Interestingly, a nearly identical model fit was achieved with a higher effusion rate (1250 m 3 /s) and correspondingly lower crust cover. In this scenario, modeling the two-component emissivity was critical for accurate model results. This represents the first study to implement two-component emissivity into thermo-rheological modeling of lava flows. The results show that this is an important factor for model accuracy and critical for large, higher effusion rate flows as well as for our understanding of older, “data-limited” flows on Earth and other planets.

New arsenate minerals from the Arsenatnaya fumarole, Tolbachik volcano, Kamchatka, Russia. XI. Anatolyite, Na6(Ca,Na)(Mg,Fe3+)3Al(AsO4)6

AbstractThe new mineral anatolyite Na6(Ca,Na)(Mg,Fe3+)3Al(AsO4)6 was found in the Arsenatnaya fumarole, Tolbachik volcano, Kamchatka, Russia. It is associated with potassic feldspar, hematite, tenorite, cassiterite, johillerite, tilasite, ericlaxmanite, lammerite, arsmirandite, sylvite, halite, aphthitalite, langbeinite, anhydrite, wulffite, krasheninnikovite, fluoborite, pseudobrookite and fluorophlogopite. Anatolyite occurs as aggregates (up to 2 mm across) of rhombohedral–prismatic, equant or slightly elongated along [001] crystals up to 0.2 mm. The mineral is transparent, pale brownish–pinkish, with vitreous lustre. It is brittle, cleavage was not observed and the fracture is uneven. The Mohs’ hardness is ca 4½. Dcalc is 3.872 g cm–3. Anatolyite is optically uniaxial (–), ω = 1.703(4) and ε = 1.675(3). Chemical composition (wt.%, electron microprobe) is: Na2O 16.55, K2O 0.43, CaO 2.49, MgO 5.80, MnO 0.16, CuO 0.69, ZnO 0.55, Al2O3 5.01, Fe2O3 7.94, TiO2 0.18, SnO2 0.17, SiO2 0.04, P2O5 0.55, As2O5 60.75, SO3 0.03, total 101.34. The empirical formula based on 24 O apfu is (Na5.90K0.10)Σ6.00(Ca0.50Na0.13Zn0.08Mn0.03)Σ0.74(Mg1.63Fe3+1.12Al0.15Cu0.10)Σ3.00(Al0.96Ti0.03Sn0.01)Σ1.00(As5.97P0.09Si0.01)Σ6.07O24. Anatolyite is trigonal, R$\bar{3}$c, a = 13.6574(10), c = 18.2349(17) Å, V = 2945.6(4) Å3 and Z = 6. The strongest reflections of the powder XRD pattern [d,Å(I)(hkl)] are: 7.21(33)(012), 4.539(16)(113), 4.347(27)(211), 3.421(20)(220), 3.196(31)(214), 2.981(17)(223), 2.827(100)(125) and 2.589(18)(410). The crystal structure was solved from single-crystal XRD data to R = 4.77%. The structure is based on a 3D heteropolyhedral framework formed by M4O18 clusters [M1 = Al and M2 = (Mg,Fe3+)] linked with AsO4 tetrahedra. (Ca,Na) and Na cations centre A1O6 and A2O8 polyhedra in voids of the framework. Anatolyite is isostructural with yurmarinite. The new mineral is named in honour of the outstanding Russian crystallographer, mineralogist and mathematician Anatoly Kapitonovich Boldyrev (1883–1946).

Principles of Creation of Local Network for Lightning Discharge Observations on Active Volcanoes of Kamchatka Peninsula

To investigate the thunderstorm activity according to electromagnetic radiation recorded data, it is necessary to create a local network which will be located near the Klyuchevskaya Sopka, Shiveluch and Tolbachik volcanoes. VLF direction finders, electric field sensors, synchronization system, auxiliary equipment will be installed at observation points. Based on the analysis of waveforms and spectral-temporal characteristics, the locations of radiation sources, their belonging to a certain class will be determined. The parameters, by which volcanic lightning differs from ordinary ones, will be determined. Examples of electromagnetic radiation occurring near the Shiveluch volcano are given. The information can be further used to monitor thunderstorm and volcanic activities.**

я глиноземДельталюмит — новая природная модификациа со шпинелеподобной структурой

The new mineral deltalumite, an analogue of the spinel-type synthetic δ-Al 2 O 3 , the second, after corundum α-Al 2 O 3 , natural modification of alumina, was found in products of two eruptions of the Ploskiy Tolbachik Volcano (Kamchatka, Russia). It occurs in pores of basalt lava and basalt scoria altered by fumarolic gas. The mineral forms roundish aggregations up to 0.2 mm across which consist of blocky, coarse prismatic individuals up to 0.03 mm in size. Deltalumite is pale yellowish, pale beige or white, translucent, with vitreous lustre. The mineral is brittle. D calc = 3.663 g cm –3 . Deltalumite is optically uniaxial (–), ω = 1.654(2), e = 1.653(2) (λ = 589 nm). Chemical composition (electron microprobe) is: Al 2 O 3 99.74, SiO 2 0.04, total 99.78 wt %. The strongest reflections of powder X-ray diffraction pattern [ d ,A( I )( hkl )] are: 2.728(61)(202), 2.424(51)(212), 2.408(49)(213), 2.281(42)(206), 1.993(81)(1.0.11, 220, 221), 1.954(48)(0.0.12) and 1.396(100)(327, 400, 2.1.14). The mineral is tetragonal, space group P -4 m 2 (by analogy with synthetic δ-Al 2 O 3 ), unit-cell dimensions are: a = 5.608(1), c = 23.513(7) A, V = 739.4(4) A 3 and Z = 16. Deltalumite belongs to the spinel subgroup within the oxyspinel group, its structural formula can be written as (Al 0.67 □ 0.33 )Al 2 O 4 in which □ means vacancy. The new mineral can be clearly distinguished from other modifications of alumina using powder X-ray diffraction pattern or IR spectrum.