Сибирский федеральный университет

Тип публикации: статья из журнала

Год издания: 2011

Идентификатор DOI: 10.1134/S1075701511080022

Ключевые слова: Cation ordering, Chemical compositions, Electron microprobes, Empirical formulas, Fibrous crystals, Grossular, Hercynite, Hibonite, In-vacuum, Inter-growths, IR spectrum, Kuznetsky Alatau, Moscow , Russia, New mineral, New mineral species, OH group, Oxygen atom, Russian Academy of Sciences, Space Groups, Structural data, Tetrahedral coordination, Unit cell parameters, Weight loss, X ray spectrum, Carbonate minerals, Chemical analysis, Crystal structure, Iodine, Iron oxides, Manganese, Manganese oxide, Perovskite, Phosphate minerals, Positive ions, Rare earth compounds, Silicate minerals, X ray powder diffraction, X rays, Aluminum, cation, chemical composition, cleavage, crystallography, infrared spectroscopy, skarn, tashelgite, X-ray diffraction, Kuznetsk Alatau, Russian Federation

Аннотация: A new mineral species has been discovered at the calc-skarnoid occurrence near the mouth of the Tashelga River, Kuznetsky Alatau, Gorny Shoria, Russia, and named after the locality of its discovery. Associated minerals are calcite, hibonite, grossular, vesuvianite, hercynite, magnetite, corundum, perovskite, scapolite, diopside, and apatite. The new mineral occurs as prismatic or finely fibrous crystals up to 1.5-2.0 mm in length, their parallel intergrowths, and felty aggregates as large as 10 mm across. Tashelgite is bluish green, translucent to transparent, with vitreous luster; D (calc) = 3.67 g/cm(3). The IR spectrum does not contain bands of OH groups. Tashelgite is biaxial (-), with alpha = 1.736(2), beta = 1.746(2), gamma = 1.750(2); 2V (meas) = -20(2)A degrees. Dispersion is strong, r Y (yellowish green) > Z (almost colorless). Chemical composition (electron microprobe, average of five-point analyses, Fe2O3 is estimated from the ratio of intensities I(Fe-K beta 5)/I(Fe-K beta 1) in the X-ray spectrum, H2O was determined as a weight loss on heating in vacuum up to 1000A degrees C), wt %: 7.98 CaO, 6.75 MgO, 0.45 MnO, 11.32 FeO, 1.40 Fe2O3, 70.70 Al2O3, 1.8(2) H2O, 100.40 in total. The empirical formula calculated on the basis of 17 oxygen atoms is H1.27Ca0.90Mg1.06Mn0.04 Fe (1.00) (2+) Fe (0.11) (3+) Al8.80O17.00. The idealized formula is CaMgFe2+Al9O16(OH). According to single-crystal X-ray structural data, tashelgite is monoclinic, pseudoorthorhombic, space group Pc; unit cell parameters are: a = 5.6973(1), b = 17.1823(4), c = 23.5718(5); beta = 90.046(3)A degrees; V = 2307.5(1)(3), Z = 8. The crystal structure of tashelgite is unique and characterized by ordering of all cations; Al occupies sites with octahedral and tetrahedral coordination. The cation ordering has also been confirmed by IR spectroscopy. The strongest lines of the X-ray powder diffraction pattern (d, ]-I[hkl] are: 11.79-48 [002], 2.845-43 [061], 2.616-100 [108], 2.584-81 [146], 2.437-44 [163], 2.406-61 [057], 2.202-72 [244]. The type specimen of tashlegite has been deposited at the Fersman Mineralogical Museum of the Russian Academy of Sciences, Moscow, Russia.

Журнал: GEOLOGY OF ORE DEPOSITS

Выпуск журнала: Vol. 53, Is. 8

Номера страниц: 751-757

ISSN журнала: 10757015

Место издания: NEW YORK

Издатель: MAIK NAUKA/INTERPERIODICA/SPRINGER

• Ananyev S.A. (Siberian Federal University)
• Konovalenko S.I. (Tomsk State University)
• Rastsvetaeva R.K. (Institute of Crystallography,Russian Academy of Sciences)
• Aksenov S.M. (Institute of Crystallography,Russian Academy of Sciences)
• Chukanov N.V. (Institute of Problems of Chemical Physics,Russian Academy of Sciences)
• Sapozhnikov A.N. (Institute of Geochemistry, Siberian Branch,Russian Academy of Sciences)
• Zagorsky V.E. (Institute of Geochemistry, Siberian Branch,Russian Academy of Sciences)
• Virus A.A. (Institute of Experimental Mineralogy,Russian Academy of Sciences)

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