MS13-P10 Solid-state synthesis and structural characterization of novel geo-inspired sulfate, Na2CuM2(SO4)4 (M=Mg, Zn). Sulfates attract considerable attention due to their wide distribution in nature. A large group of anhydrous sulfate minerals is formed in high-temperature exhalative processes in fumaroles of volcanoes. Many of the exhalative minerals demonstrate unique structure types and may be of interest from the view point of materials science.
Itelmenite, Na2CuMg2(SO4)4, was recently found in a fumarole of the Naboko scoria cone of the Fissure Tolbachik volcano eruption (2012-2013), Kamchatka Peninsula, Russia . [M2+3(SO4)4]2- sulphate framework in itelmenite is unique and has not been described before in minerals or synthetic compounds. Sulphate tetrahedra are packed into pseudolayered arrangements perpendicular to the a axis. Structure topology of itelmenite is rather simple. Each MO5 or MO6 polyhedron shares all common corners with sulphate tetrahedra thus forming heteropolyhedral framework with voids filled by Na+ cations.
Single crystals of Mg- and Zn-dominant synthetic analogues of itelmenite were grown by the solid-state reaction from the mixture containing equimolar quantities of anhydrous CuSO4, Na2SO4, MgSO4 or ZnSO4. Na2CuMg2(SO4)4 (1) and Na2CuZn2(SO4)4 (2) are orthorhombic, Pbca. 1: a = 9.531(6) Å, b = 8.745(6) Å, c = 28.72(2) Å, V = 2393.3(3) Å3. 2: a = 9.458(5) Å, b = 8.811(4) Å, c = 28.850(15) Å, V = 2404(2) Å3. Mixed cationic character of M1, M2 and M3 sites is similar to that observed in natural sample. Symmetrical M3 octahedral site is occupied exclusively by Mg and Zn in the structures of 1 and 2, respectively.
Obtained materials were investigated using powder X-ray diffraction, high-temperature powder X-ray diffraction, IR spectroscopy and DSC-TGA.
This work was ﬁnancially supported by the Russian Science Foundation through the grant 16-17-10085. Ph.D. of D.O.N. is carried out within the framework of the international French–Russian co-tutorial Ph.D. program. D.O.N. also acknowledges support of the Saint-Petersburg State University through its internal grant. Technical support by the SPbSU X-ray Diffraction Resource Centre is gratefully acknowledged.
 Nazarchuk E.V., Siidra O.I., Agakhanov A.A., Lukina E.A., Avdontseva E.Y., Karpov G.A. (2018) Itelmenite, Na2CuMg2(SO4)4, a new anhydrous sulphate mineral from the Tolbachik volcano. Mineralogical Magazine, in press DOI: 10.1180/minmag.2017.081.089.Keywords: sulphates, minerals, materials