Lidiya P. Vergasova

Prewittite, KPb1.5Cu6Zn(SeO3)2O2Cl10, a new mineral from Tolbachik fumaroles, Kamchatka peninsula, Russia: Description and crystal structure

Abstract Prewittite, ideally KPb1.5Cu6Zn(SeO3)2O2Cl10, was found in the fumarole field of the second cinder cone of the North Breach of the Great fissure Tolbachik eruption (1975-1976, Kamchatka peninsula, Russia). It occurs as separate olive-green tabular crystals up to 0.2 mm in maximum dimension. It has vitreous luster and brownish-green streak. Prewittite is orthorhombic, space group Pnnm, a = 9.132(2), b = 19.415(4), c = 13.213(3) Å, V = 2342.6(9) Å3, Z = 4, Dcalc = 3.89 g/cm3, Dmeas = 3.90(2) g/cm3. The eight strongest lines of the powder X-ray diffraction pattern are {I [d(Å)] hkl}: 70 (8.26) 110; 60 (7.53) 101; 90 (4.111) 220, 132, 141; 100 (3.660) 212, 123; 40 (2.996) 223; 50 (2.887) 062; 40 (2.642) 322, 214; 40 (2.336) 073, 180, 244. Prewittite is biaxial (-). The optical orientation is X = a, Y = c, Z = b. The mineral has clear pleochroism: X, Y - olive green, Z - red-brown. The mineral is very brittle with the perfect cleavage on (010) and (101). The most developed crystal forms are {010}, {001}, and {101}. The chemical composition determined by the electron-microprobe is (wt%): K2O 1.76, PbO 21.18, CuO 33.24, ZnO 8.00, SeO2 15.74, Cl 26.06, O=Cl -5.88, total 100.10. The empirical formula derived on the basis of O+Cl = 18 and sum of positive charges of cations equal to 26 is K0.53Pb1.33Cu5.87Zn1.38Se1.99O7.67Cl10.33. The crystal structure was solved by direct methods and refined to an agreement index R1 = 0.034 on the basis of 1522 independent reflections with I ≥ 2σI. It is based upon metal oxide selenite chloride layers parallel to (010) and linked through K-Cl and Pb-Cl bonds to the K and Pb atoms located in the interlayer. The mineral name honors Charles T. Prewitt (b. 1933) in recognition of his important contributions to crystal chemistry of minerals and planetary materials.

Nicksobolevite, Cu7(SeO3)2O2Cl6, a new complex copper oxoselenite chloride from Tolbachik fumaroles, Kamchatka peninsula, Russia

Nicksobolevite, ideally Cu7(SeO3)2O2Cl6, was found in a fumarole of the second cinder cone of the North Breach of the Great Fissure Tolbachik volcano eruption (1975–1976), Kamchatka Peninsula, Russia. The mineral occurs as aggregates of red needle-like crystals up to 0.4 mm in maximal dimension, elongated along [001]. Associated minerals are chloromenite, prewittite, melanothallite, sophiite, ralstonite, ponomarevite, and native gold. Nicksobolevite is monoclinic, P 21/ c , a = 10.958(9), b = 14.483(5), c = 10.494(14) A, β = 113.61(7)°, V = 1526(3) A3, Z = 4 (from powder diffraction data). The eight strongest lines of the X-ray powder diffraction pattern are ( I-d-hkl ): 77-8.25-(110); 100-5.877-(120); 26-4.239-(112); 37-3.619-(040); 95-3.257-(310), (321); 50-2.715-(402); 26-2.668-(033), (411); and 40-2.278-(242), 134). Nicksobolevite is dark red, with vitreous luster and orange-red streak. The mineral is very brittle and transparent. Cleavage is perfect on {010} and {−101} and good on {120}. The Mohs hardness measured by microindentation is 2–2½. The calculated density is 4.18 g/cm3 (based on the empirical chemical formula). Nicksobolevite is optically positive, with α = 2.00(1), β = 2.01(1), γ = 2.08(1), 2Vcalc. = 43°, and the orientation is X = b , Z^c = 36° (in obtuse β). Pleochroism: X , Y = red, Z = brownish red. The chemical composition determined by the electron-microprobe analysis is (wt. %): CuO 56.17, ZnO 2.34, SeO2 23.29, Cl 22.69, O = Cl −5.13, total 99.36. The empirical formula of nicksobolevite, calculated on the basis of 14 anions per formula unit, is (Cu6.71Zn0.27)∑6.98Se1.99O7.92Cl6.08. The simplified formula is Cu7(SeO3)2O2Cl6, which requires CuO 59.02, SeO2 23.52, Cl 22.54, O = Cl −5.09, total 100.00 wt%. The crystal structure was solved by direct methods and refined to an agreement index R 1 = 0.075 on the basis of 3590 independent observed reflections. The structure contains eight symmetrically independent Cu2+ positions with coordination numbers varying from 5 to 6. The crystal structure is based upon [O4Cu13] tetramers consisting of four corner-sharing OCu4 tetrahedra. The tetrahedra are surrounded by the Se1O3 and Se2O3 selenite triangular pyramids to form linear {[O4Cu13](SeO3)4} complexes oriented parallel to [210] and [−210] and linked to each other into layers with a ladder-like configuration. The layers are perpendicular to the a axis and are surrounded by Cl− anions, which provide their linkage in the [100] direction. The mineral is named in honor of Academician Nikolay (Nick) Vladimirovich Sobolev (b. 1935), in recognition of his important contributions to mineralogy and petrology. Nicksobolevite is the most structurally complex and Cl-rich copper selenite chloride known so far.

Hatertite, Na2(Ca, Na)(Fe3+, Cu)2(AsO4)3, a new alluaudite-group mineral from Tolbachik fumaroles, Kamchatka peninsula, Russia

Hatertite, ideally Na 2 (Ca, Na)(Fe 3+ , Cu) 2 (AsO 4 ) 3 , was found in a fumarole of the North Breach of the Great fissure Tolbachik volcano eruption (1975–1976), Kamchatka Peninsula, Russia. The mineral occurs as individual, prismatic and tabular, honey-yellow crystals up to 0.3 mm across. It has a vitreous luster and yellow streak. Hatertite is monoclinic, C 2/ c , a = 12.590(2), b = 12.993(3), c =6.700(2) A, β =113.72(2)°, V = 1003.4(3) A 3 , Z =4, D calc = 4.06 g/cm 3 . The eight strongest lines of the powder X-ray diffraction pattern are [ d obs in A ( I ) ( hkl )]: 6.493(25)(020); 3.628 (25)(131); 3.204(39)( 112,131); 3.065(18)(002); 2.976(28)(312, 222); 2.830(100)(240), 2.632(36)(132); 1.647(19)(204,640). Hatertite is optically positive, α = 1.820(3), β = 1.825(3), γ = 1.833(3), 2V meas. = 60(10)°, 2V calc. = 77°. The orientation is Y = b . The chemical composition determined by the electron-microprobe analysis is as follows (wt.%): Na 2 O 8.49, K 2 O 2.41, MnO 1.64, CaO 7.06, Fe 2 O 3 11.15, ZnO 2.05, CuO 8.10, Al 2 O 3 2.22, As 2 O 5 55.67, total 98.79. The empirical formula (based on 12 O apfu ) is (Na 0.47 K 0.32 )(Na 0.84 Ca 0.16 ) (Ca 0.62 Na 0.19 Zn 0.16 Mn 0.14 ) (Fe 3+ 0.44 Cu 0.32 Al 0.13 Na 0.11 ) 2 (As 1.01 O 4 ) 3 . A general crystal chemical formula for hatertite should be written as NaNa(Ca 1−x M + x )(Fe 3+ 1+x M 2+ 1−x )(AsO 4 ) 3 , where 0.5 > x >0, M + is an unspecified monovalent cation, and M 2+ is an unspecified divalent cation. The crystal structure was solved by direct methods and refined to an agreement index R 1 = 0.028 on the basis of 751 independent observed reflections. Hatertite is a new arsenate member of the alluaudite group. Its structure is based upon chains of edge-sharing octahedra running along [−101] and linked by T (2)O 4 tetrahedra into layers parallel to (010). The layers are further interlinked through T (1)O 4 tetrahedra to form a three-dimensional octahedral-tetrahedral framework with the A (1) and A (2)’ sites in the interstices. The mineral was named in honor of Prof. Frederic Hatert (b. 1973), University of Liege, Belgium, for his contributions to the mineralogy and crystal chemistry of alluaudite-group minerals.

Urusovite, Cu[AlAsO5], a new mineral from the Tolbachik volcano, Kamchatka, Russia

Urusovite, ideally Cu[AlAsO 5 ], has been found in a fumarole in the North Breach of the great fissure Tolbachik eruption (1975-76, Kamchatka peninsula, Russia). It occurs as light-green plates up to 0.4 mm in maximal dimension, tabular on {100}, elongated along [001]; well-developed forms are {100}, {010}, {110}, {011}, {111}. Associated minerals are: ponomarevite, piypite, sylvite, dolerophanite, euchlorine, tenorite, hematite and two unknown As-bearing minerals. Urusovite is brittle and has a perfect cleavage on (100), a vitreous luster and a white streak. H = 379 kg/mm 2 . Biaxial, optically negative. α = 1.672(2), β = 1.718(2), γ = 1.722(2), 2V meas ∼ 30(2)°, 2V cale = 32.2°. Optical orientation is b = β, c - α. Pleochroism is in the light-green tones: α - colourless, β - light-green, γ - light-green. The mineral is monoclinic, space group P 2 1 / c, a = 7.314(2), b = 10.223(3), c = 5.576(2) A, β = 99.79(3)°, V = 410.9(2) A 3 . The diagnostic lines of the X-ray powder diffraction pattern are (I-d-hkl): 100-7.20-100; 9-4.844-011; 23-4.327-111; 10-3.604-200; 10-3.174-121; 20-3.125-211; 6-2.656-012; 8-2.458-221. Urusovite is isostructural with Fe 2+ [AlPO 5 ]. Microprobe analysis gave the following chemical composition (wt. %): CuO 32.23 (30.97-32.82), Al 2 O 3 20.89 (20.44-21.44), Fe 2 O 3 0.32 (0.10-0.72), ZnO 0.25 (0.10-0.43), As 2 O 5 46.02 (44.97-47.17), V 2 O 5 0.12 (0.00-0.40), Σ99.83 (98.71-100.64). The empirical formula of urusovite, (Cu 0.99 Zn 0.01 ) Σ1.00 Al 1.00 As 0.98 O 5.00’ calculated on the basis of 5 O atoms, is close to the ideal one, Cu[AlAsO 5 ], confirmed by crystal-structure analysis. The mineral is named urusovite in honour of Vadim Sergeevich Urusov (1936-), crystal chemist, Corresponding Member of the Russian Academy of Sciences, chair of the Department of Crystallography and Crystal Chemistry of Moscow State University.

Lammerite-β, Cu3(AsO4)2, a new mineral from fumaroles of the Great Fissure Tolbachik eruption, Kamchatka Peninsula, Russia

Lammerite-β, Cu3(AsO4)2, occurs as a product of the post-eruption fumarole activity of the second cinder cone of the North breach of the Great Fissure Tolbachik eruption in 1975–1976, Kamchatka Peninsula, Russia. Sporadic light to dark green splinter-shaped grains are no larger than 0.15 mm in size. Cleavage is not observed. The mechanical admixture of finely dispersed hematite forms condensed brownish spots that are occasionally zonal relative to the contours of the lammerite-β grains. Associated minerals are euchlorine, piypite, alumoklyuchevskite, alarsite, and lammerite. Lammerite-β is brittle and transparent and has vitreous luster. The calculated density is 5.06 g/cm3. The mineral is not pleochroic, biaxial (+), α = 1.887(5), β = 1.936(5), γ = 2.01(1), 2V(calc.) = 80.9°; dispersion is strong, r < v. The new mineral is monoclinic, the space group is P21/c, a = 6.306(1), b = 8.643(1), c = 11.310(1) Å, β = 92.26(1)°, V = 615.9(1) Å3, and Z = 4. Characteristic reflections in the X-ray powder diffraction pattern (I-d-hkl) are 100-2.83-004, 10-5.65-002, and 10-4.32-020. The chemical composition is as follows, wt %: 51.30 CuO, 0.32 ZnO, 49.12 As2O3, with a total of 100.74 wt %. The empirical and idealized formulas are Cu3.00Zn0.02As1.99O8 and Cu3(AsO4)2, respectively.

Unique thallium mineralization in the fumaroles of Tolbachik volcano, Kamchatka Peninsula, Russia. I. Markhininite, TlBi(SO4)2

Abstract Markhininite, ideally TlBi(SO4)2, was found in a fumarole of the 1st cinder cone of the North Breach of the Great Fissure Tolbachik volcano eruption (1975-1976), Kamchatka Peninsula, Russia. Markhininite occurs as white pseudohexagonal plates associated with shcherbinaite, pauflerite, bobjonesite, karpovite, evdokimovite and microcrystalline Mg, Al, Fe and Na sulfates. Markhininite is triclinic, P1̄ , a = 7.378(3), b = 10.657(3), c = 10.657(3) Å , α = 61.31(3), β = 70.964(7), γ = 70.964(7)°, V = 680.2(4) Å3, Z = 4 (from single-crystal diffraction data). The eight strongest lines of the X-ray powder diffraction pattern are (I/d/hkl): 68/4.264/111, 100/3.441/113, 35/3.350/222, 24/3.125/122, 23/3.054/202, 45/2.717/022, 20/2.217/331, 34/2.114/204. Chemical composition determined by electron microprobe analysis is (wt.%): Tl2O 35.41, Bi2O3 38.91, SO3 25.19, total 99.51. The empirical formula based on 8 O a.p.f.u. is Tl1.04Bi1.05S1.97O8. The simplified formula is TlBi(SO4)2, which requires Tl2O 35.08, Bi2O3 38.48, SO3 26.44, total 100.00 wt.%. The crystal structure was solved by direct methods and refined to R1 = 0.055 on the basis of 1425 independent observed reflections. The structure contains four Tl+ and two Bi3+ sites in holodirected symmetrical coordination. BiO8 tetragonal antiprisms and SO4 tetrahedra in markhininite share common O atoms to produce [Bi(SO4)2]- layers of the yavapaiite type. The layers are parallel to (111) and linked together through interlayer Tl+ cations. The mineral is named in honour of Professor Yevgeniy Konstantinovich Markhinin (b. 1926), Institute of Volcanology, Russian Academy of Sciences, Kamchatka peninsula, Russia, in recognition of his contributions to volcanology. Markhininite is the first oxysalt compound that contains both Tl and Bi in an ordered crystal structure.

Unique thallium mineralization in the fumaroles of the Tolbachik volcano, Kamchatka Peninsula, Russia. II. Karpovite, Tl2VO(SO4)2(H2O)

Abstract Karpovite, ideally Tl2VO(SO4)2(H2O), was found in a fumarole of the 1st cinder cone of the North Breach of the Great Fissure Tolbachik volcano eruption (1975-1976), Kamchatka Peninsula, Russia. Karpovite occurs as bundles of white, needle-like crystals associated with shcherbinaite, pauflerite, bobjonesite, markhininite, evdokimovite and microcrystalline Mg, Al, Fe and Na sulfates. Karpovite is monoclinic, P21, a = 4.6524(4), b = 11.0757(9), c = 9.3876(7) Å , β = 98.353(2)°, V = 478.60(7) Å3, Z = 2 (from single-crystal diffraction data). The eight strongest lines of the X-ray powder diffraction pattern are (I/d/hkl): 64/4.289/012, 81/4.253/110, 38/3.683/111, 47/3.557/022, 100/3.438/1̄21, 52/2.982/013, 59/2.945/112, 54/2.354/132. The chemical composition determined by the electron microprobe analysis is (wt.%) Tl2O 61.43, VO2 11.53, SO3 23.55, H2O 2.61, total 99.12. The empirical formula (calculated on the basis of 10 O a.p.f.u.) is Tl2.00V0.96S2.03O9(H2O). The simplified formula of karpovite is Tl2VO(SO4)2(H2O), which requires Tl2O 61.93, VO2 12.09, SO3 23.34, H2O 2.62 total 100.00 wt.%. The crystal structure was solved by direct methods and refined to R1 = 0.026 for 4196 independent observed reflections. The structure contains two symmetrically independent Tl+ sites, one V4+ site and two S6+ sites. VO5H2O octahedra and SO4 tetrahedra link together by sharing corners to form kröhnkite-type stripes parallel to the a axis with their planes oriented parallel to (021) and (021̄). Tl+ cations are located between the chains, linked into a three-dimensional structure. The new mineral is named in honour of Professor Gennadii Alexandrovich Karpov (b. 1938), volcanologist at the Institute of Volcanology, Russian Academy of Sciences, Petropavlovsk-Kamchatskii, Kamchatka Peninsula, Russia.

Unique thallium mineralization in the fumaroles of Tolbachik volcano, Kamchatka Peninsula, Russia. III. Evdokimovite, Tl4(VO)3(SO4)5(H2O)5

Abstract Evdokimovite, ideally Tl4(VO)3(SO4)5(H2O)5, was found in a fumarole of the 1st cinder cone of the North Breach of the Great Fissure Tolbachik volcano eruption of 1975-1976, Kamchatka Peninsula, Russia. Evdokimovite occurs as thin, colourless needles up to 0.09 mm long associated with shcherbinaite, pauflerite, bobjonesite, markhininite, karpovite and microcrystalline Mg, Al, Fe and Na sulfates. Evdokimovite is monoclinic, P21/n, a = 6.2958(14), b = 10.110(2), c = 39.426(11) Å, β = 90.347(6)°, V = 2509.4(10) Å3 and Z = 4 (from single-crystal diffraction data). The eight strongest lines of the powder X-ray diffraction pattern are (I/d/hkl): 57/9.793/011, 100/8.014/013, 26/6.580/006, 19/ 4.011/026, 29/3.621/118, 44/3.522/125, 19/3.010/036, 21/2.974/212. Chemical composition determined by the electron microprobe analysis is (wt.%): Tl2O 55.40, VO2 14.92, SO3 25.83, H2O 5.75, total 101.90. The empirical formula for evdokimovite calculated on the basis of (Tl + V + S) = 12 a.p.f.u. is Tl4.10V2.83S5.07H10.00O27.94. The simplified formula is Tl4(VO)3(SO4)5(H2O)5. The crystal structure was solved by direct methods and refined to R1 = 0.11 on the basis of 3660 independent observed reflections. V4+O6 octahedra and SO4 tetrahedra share common corners to form two types of vanadyl-sulfate chains, [(VO)(H2O)2(SO4)2]2- and [(VO)2(H2O)3(SO4)3]2-. Thallium atoms are located in between the chains. The structure can be described as a stacking of layers of two types, A and B. The A layer contains [(VO)2(H2O)3(SO4)3]2- chains and the Tl2 and Tl3 atoms, whereas the B layer contains [(VO)(H2O)2(SO4)2]2- chains and the Tl1 atoms. Stacking of the layers can be described as ...A’*BAA’B*A*..., where A and A’ denote A layers with opposite orientations of the [(VO)2(H2O)3(SO4)3]2- chains, and the A* and B* layers are rotated by 180° relative to the A and B layers, respectively. [(VO)2(H2O)3(SO4)3]2- chains are modulated and are arranged to form elliptical tunnels hosting disordered Tl(4), Tl(4A) and Tl(4B) sites. The new mineral is named in honour of Professor Mikhail Dmitrievich Evdokimov (1940-2010), formerly of the Department of Mineralogy, St Petersburg State University, for his contributions to mineralogy and petrology, and especially for teaching mineralogy to several generations of students at the University. Evdokimovite is the most complex V4+ sulfate known to date with structural information amounting to 1130 bits per unit cell, which places evdokimovite among minerals with the complexity of the vesuvianite group.

Ivsite, Na3H(SO4)2, a new mineral from volcanic exhalations of fumaroles of the Fissure Tolbachik Eruption of the 50th Anniversary of the Institute of Volcanology and Seismology, Far East Branch, Russian Academy of Sciences

Fine-granular (<0.1 mm) flattened colorless transparent crystals of ivsite form white aggregates. The empirical formula (Na2.793Cu0.056)2.849HS2.016O8 is close to the ideal Na3H(SO4)2. The structure was refined up to R = 0.040. Ivsite has a monoclinic symmetry, P21/c, a = 8.655(1) Å, b = 9.652(1) Å, c = 9.147(1) Å, β = 108.76(1)°, V = 723.61(1) Å3, Z = 4. Na atoms occur at six- and seven-fold sites (NaO6 and NaO7); S atoms, in isolated SO4 tetrahedrons; these polyhedrons form a three-dimensional framework. The diagnostic lines of powder diffraction patterns (d[Å]–I–hkl) are 4.010–53–12-1, 3.949–87–012, 3.768–100–210, 3.610–21–20-2, 3.022–22–031, 2.891–42–22-2, 2.764–49–31-1, and 2.732–70–13-1.

Thermal expansion of new arsenate minerals, bradaczekite, NaCu4(AsO4)3, and urusovite, Cu(AsAlO5)

Thermal behavior of two new exhalation copper-bearing minerals, bradaczekite and urusovite, from the Great Tolbachik Fissure Eruption (1975–1976, Kamchatka Peninsula, Russia) has been studied by X-ray thermal analysis within the range 20–700°C in air. The following major values of the thermal expansion tensor have been calculated for urusovite: α11 = 10, α22 = αb = 7, α33 = 4, αV = 21 × 10−6°C−1, μ = c∧α33 = 49° and bradaczekite: α11aver = 23, α22 = 8, α33aver = 6 × 10−6°C−1, μ(c∧α33) = 73°. The sharp anisotropy of thermal deformations of these minerals, absences of phase transitions, and stability of the minerals in the selected temperature range corresponding to conditions of their formation and alteration during the posteruption period of the volcanic activity are established.