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IMA 2014-025 = katiarsite (1 reply)

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Reference:
▪ Pekov, I.V., Yapaskurt, V.O., Britvin, S.N., Zubkova, N.V., Vigasina, M.F., Sidorov, E.G. (2016): New arsenate minerals from the Arsenatnaya fumarole, Tolbachik volcano, Kamchatka, Russia. V. Katiarsite, KTiO(AsO4). Mineralogical Magazine, 80, 639-646.

Abstract:
A new mineral katiarsite, ideally KTiO(AsO4), occurs in sublimates of 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 hatertite, bradaczekite, johillerite, yurmarinite, tilasite, arsmirandite, hematite, tenorite, As-bearing orthoclase, fluorophlogopite and aphthitalite. Katiarsite occurs as long prismatic to acicular, typically sword-like crystals up to 3 x 10 x 50 um, rarely up to 0.15 mm long. Crystal forms are: {011}, {201}, {100} and {001}. Katiarsite is transparent, colourless, with vitreous lustre. The mineral is brittle. Cleavage was not observed, the fracture is uneven. Dcalc is 3.49 g cm-3. Katiarsite is optically biaxial (+), alpha = 1.784(3), beta = 1.792(3), gamma = 1.870(5), 2Vobs is small. Orientation: X = b, Y = a, Z = c. The Raman spectrum is reported. The chemical composition (wt%, electron-microprobe data) is: K2O 18.98, Fe2O3 5.07, TiO2 27.49, As2O5 47.48, total 99.02. The empirical formula, calculated based on 5 O apfu, is: K1.00(Ti0.85Fe3+0.16)1.01As1.02O5. The strongest reflections of the powder X-ray diffraction pattern [d,Å(I)(hkl)] are: 5.91(17)(110), 5.62(74)(011), 4.18(19)(202), 3.157(66)(013), 2.826(100)(221), 2.809(96)(022) and 2.704(19)(004). Katiarsite is orthorhombic, a = 13.174(4), b = 6.5635(10), c = 10.805(2) Å, V = 934.3(3) Å3 and Z = 8 (single-crystal XRD data). Space group is Pna21, by analogy with KTA, the synthetic KTiO(AsO4), a very important non-linear optical crystalline 35 material. The name of the mineral reflects its chemical composition, kalium titanyl arsenate.

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