Saranovskite, SrCaFe 2+ 2 (Cr 4 Ti 2 )Ti 12 O 38 , a new crichtonite-group mineral
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ORIGINAL PAPER
Saranovskite, SrCaFe2+2(Cr4Ti2)Ti12O38, a new crichtonite‑group mineral Nikita V. Chukanov1,2 · Ramiza K. Rastsvetaeva3 · Olga N. Kazheva1 · Oleg K. Ivanov4 · Igor V. Pekov2,5 · Atali A. Agakhanov6 · Konstantin V. Van7 · Vasiliy D. Shcherbakov2 · Sergey N. Britvin8 Received: 16 August 2020 / Accepted: 9 October 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract The new crichtonite-group mineral saranovskite, ideally SrCaFe2+2(Cr4Ti2)Ti12O38, was discovered in the Glavnoe Saranovskoe deposit, Middle Urals, Russia, and named after the type locality. The associated minerals are chromite, Cr-bearing clinochlore, and calcite. Saranovskite forms black crude equant crystals about 2 mm across. The lustre is submetallic, and the streak is brownish-gray. Cleavage is not observed. The Mohs hardness is 6. Density calculated using the empirical formula is equal to 4.501 g cm–3. The reflectance spectra in visible range are given. The IR spectrum shows the absence of H-, B- and C-bearing groups. The Raman spectrum of saranovskite confirms the absence of H-bearing groups and indicates a rather high degree of ordering of T i4+ and lower-valence cations. The chemical composition of saranovskite is (wt.%; electron microprobe, total iron apportioned between FeO and F e2O3 taking into account charge balance): MgO 2.01, CaO 1.43, MnO 0.21, FeO 8.14, SrO 3.27, BaO 2.18, Al2O3 0.53, S c2O3 0.69, Cr2O3 10.27, F e2O3 2.19, Y2O3 1.56, La2O3 0.94, Ce2O3 0.91, P r2O3 0.14, Nd2O3 0.35, T iO2 64.25, Z rO2 0.58, total 99.65. The crystal chemical formula of saranovskite is (Sr0.55Ba0.25Ln0.10Ca0.10)(Ca0.36Y0.25Ln0.16Fe2+0.08Zr0.10Mn0.05) (Fe2+1.12Mg0.88)(Cr3+2.34Ti2.28Fe2+0.91Fe3+0.11Al0.18Sc3+0.18) (Ti5.82Fe3+0.18)Ti6.0O38. The idealized formula is S rCaFe2+2(Cr4Ti2)Ti12O38. The crystal structure was determined using single-crystal X-ray diffraction data and refined to R = 0.0243. The new mineral is isostructural to other crichtonite-group members. Saranovskite is trigonal, space group R3 , with a = 10.3553(2) Å, c = 20.7301(4) Å, V = 1925.12(8) Å3 and Z = 3. The strongest lines of the powder X-ray diffraction pattern [d, Å (I, %) (hkl)] are: 3.398 (75) (024), 2.881 (100) (– 126), 2.842 (65) (– 234), 2.247 (67) (– 144). 2.137 (76) (– 345), 1.799 (63) (– 348), 1.597 (72) (– 1.4.10, 152), 1.439 (76) (520). Keywords Saranovskite · New mineral · Crichtonite group · Crystal structure · IR spectroscopy · Raman spectroscopy · Glavnoe Saranovskoe deposit · Middle urals
Oleg K. Ivanov deceased 01 February 2020. * Nikita V. Chukanov [email protected] 1
Institute of Problems of Chemical Physics, Russian Academy of Sciences, Moscow Region, Chernogolovka 142432, Russia
2
Faculty of Geology, Moscow State University, Vorobievy Gory, Moscow 119991, Russia
3
FSRC “Crystallography and Photonics”, Russian Academy of Sciences, Leninskii pr. 59, Moscow 119333, Russia
4
Institute of Geology and Geochemistry, of Urals Branch of Russian Academy of Sciences, Vonsovsky Street 15, Yekaterinb
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