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)º, 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 180º 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.

Thalliomelane, TIMn7.54+Cu0.52+O16, a new member of the coronadite group from the preglacial oxidation zone at Zalas, southern Poland

“…DOI: https://doi.org/10.2138/am-2021-7577. http://www.minsocam.org/ other Tl minerals related to oxygen: chrysothallite, K 6 Cu 6 Tl 3+ Cl 17 (OH) 4 •H O (Pekov et al 2013(Pekov et al , 2015, markhininite, TlBi(SO 4 ) 2 (Filatov et al 2013;Siidra et al 2014a), karpovite, Tl 2 VO(SO 4 ) 2 (H 2 O) (Vergasova et al 2013;Siidra et al 2014b), and evdokimovite, Tl (VO) 3 (SO 4 ) 5 (H 2 O) (Siidra et al 2013(Siidra et al , 2014c are products of the crystallization of fumarole gas; the remaining from above 100 Tl mineral species known so far are mainly sulfides, arsenoor antimono-sulfides related to hydrothermal activity. Thalliomelane and its name were approved by the Commission on New Minerals, Nomenclature and Classification of the International Mineralogical Association (IMA CNMNC), proposal 2019-055 (Gołębiowska et al 2020).…”

Kalithallite, K3Tl3+Cl6⋅2H2O, a new mineral with trivalent thallium from the Tolbachik volcano, Kamchatka, Russia

“…Three Tl + minerals were first described in sublimates of fumaroles at the La Fossa crater, Vulcano island, Aeolian archipelago, Italy, namely lafossaite Tl(Cl,Br) (Roberts et al , 2006), hephaistosite TlPb 2 Cl 5 (Campostrini et al , 2008), and steropesite Tl 3 BiCl 6 (Demartin et al , 2009). At the Tolbachik volcano, besides chrysothallite and kalithallite containing Tl 3+ , three minerals with univalent thallium were discovered: markhininite TlBi(SO 4 ) 2 , karpovite Tl 2 VO(SO 4 ) 2 (H 2 O), and evdokimovite Tl 4 (VO) 3 (SO 4 ) 5 (H 2 O) 5 (Siidra et al , 2014a, 2014b, 2014c). Nataliyamalikite TlI was found in an active fumarole at the Avacha (Avachinskiy) volcano, Kamchatka, Russia (Okrugin et al , 2017).…”

Evolution of fumarolic anhydrous copper sulfate minerals during successive hydration/dehydration

“…As a result of alteration by hydration processes, the formation of unique associations of secondary hydrated sulfate minerals has been observed (e.g. Siidra et al , 2014b,c). However, the transformation of primary fumarolic minerals under the influence of atmospheric moisture has been poorly studied to date.…”