On the Identification of Ti-Ta- Nb-Oxides in “Wiikites” from Karelia
M. Hosseinpour Khanmiri1, D. Goldwirt2, N. Platonova1, S. Janson1, Yu. Polekhovsky1, R. Bogdanov1
1Saint Petersburg State University, Saint Petersburg, Russian Federation
2Mining and Metallurgical Company “Norilsk Nickel”, Saint Petersburg, Russian Federation
Min. miner. depos. 2018, 12(1):28-38
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Purpose. With respect to the nature of Ti-Ta-Nb-oxides, which are included in the mineral associations that have historically gone by the now outdated name of “wiikites”, there is no unanimity of opinion. The main difficulty in identifying them is associated with the complexity of their chemical composition, their metamict structure and the substantial changes in their initial mineral form due to the effects of natural weathering. The aim of this work is the development of methodology to identify Ti-Ta-Nb-oxides corresponding to the mineral formulas AB2O6 and A2B2O7.
Methods. The methodology developed in the work includes two experimental approaches: 1) electron probe microanalysis of phases revealed through use of the SEM-BSE method. Based on the resulting data, a hypothesis about the nature of the Ti-Ta-Nb-oxides in a number of wiikite samples is proposed. 2) XRD analysis of those phases that are formed in the course of thermal annealing of samples from 200 to 1000°C. Based on the resulting data here, the previous hypotheses are either accepted or rejected for each sample.
Findings. Using this methodology, three “wiikite” samples were analyzed (the experimental codes were Wk-2, Wk-3 and Wk-7). The Ti-Ta-Nb-oxides in two of these wiikites (Wk-2 and Wk-3) were preliminarily determined to be hydroxyyttropyrochlore and hydroxycalciobetafite, respectively. In the third sample (Wk-7), the Ti-Ta-Nb-oxide was classified as polycrase. The results of XRD phase analysis of the annealed samples were compatible with the primary hypotheses that hydroxycalciobetafite and polycrase were the initial minerals in “wiikites” 3 and 7, respectively.
Originality. The paper considers the issue of the chemical conditions necessary for the recovery of the original Ti-Ta-Nb-oxide during recrystallization of the metamict structures. This is a problem that has not been substantively addressed in the literature. Also for the first time experimentally proved the existence of the polycrase in “wiikites”.
Practical implications. Completed work expands our knowledge of the mineral composition of the granitic pegmatites of the Baltic shield and the possibility of their use both for research purposes and for needs of national economy.
Keywords: Ti-Ta-Nb-oxides, polycrase, pyrochlore supergroup minerals, isochronous thermal annealing, SEM-BSE analysis, EMP analysis
Ambartsumyan, Z.L., Basalova, G.I., Gorzhevskaya, S.A., Nazarenko, N.G., & Hodzhaeva, R.P. (1961). Termicheskie isledovania uranovykh i uransoderzhaschikh mineralov. Moskva: Gosatomizdat.
Ant-Wuorinen, J. (1936). Der Wiikite Und Seine Chemische Zusammensetzung. Bulletin de la Commission Geologique de Finlande, (115), 213-229.
Atencio, D., Andrade, M.B., Christy, A.G., Giere, R., & Karta-shov, P.M. (2010). The Pyrochlore Supergroup of Minerals: Nomenclature. The Canadian Mineralogist, 48(3), 673-698.
Beus, A.A., & Kalita, A.P. (1961). Sovremennye dannye o tak nazyvaemom wiikite. Doklady Akademii Nauk SSSR, (141), 705-708.
Bjørlykke, H. (1931). Ein Betafitmineral von Tangen bei Kragerö. Norsk Goelisk Tidskrift, 12(1).
Bogdanov, R.V., Batrakov, Yu.F., Puchkova, E.V., Sergeev, A.S., & Burakov, B.E. (2002). A Study of Natural Minerals of the U-Pyrochlore Type Structure as Analogues of Plutonium Ceramic Waste Forms. Materials Research Society, Symposium Proceedings, (713), 295-301.
Cao, Q., Krivovichev, S.V., Burakov, B.E., & Liu, X. (2014). Natural Metamict Minerals as Analogues of Aged Radioactive Waste Forms. Journal of Radioanalytical and Nuclear Chemistry, 304(1), 251-255.
Christy, A.G., & Atencio, D. (2013). Clarification of Status of Species in the Pyrochlore Supergroup. Mineralogical Ma-gazine, 77(1), 13-20.
Ercit, T.S. (2005). Identification and Alteration Trends of Granitic Pegmatite-Hosted (Y, REE, U, Th)-(Nb, Ta, Ti) Oxide Minerals: A Statistical Approach. The Canadian Mineralogist, 43(4), 1291-1303.
Fleischer, M. (1987). Glossary of Mineral Species. Tucson, Arizona: The Mineralogical Record Inc.
Frye, K. (1983). The Encyclopedia of Mineralogy. Stroudsburg, Pennsylvania: Springer.
Glebovickiy, V.A. (2005). Ranniy dokembriy baltiyskogo shchita. Sankt-Peterburg: Nauka.
Hogarth, D.D. (1977). Classification and Nomenclature of the Pyrochlore Group. American Mineralogist, (62), 403-410.
Hosseinpour Khanmiri, M., Goldwirt, D.K., & Bogdanov, R.V. (2015). Isotopic Parameters of Uranium and Thorium in the Natural Titanium-Tantalum-Niobate. In VIII All-Russian Conference on Radiochemistry “Radiochemistry-2015” (pp. 339). Zheleznogorsk: Gorno-khimicheskiy kombinat (predpriyatie Goskorporatsii “Rosatom”).
Kalita, A.P. (1961). Redkozemel’nye pegmatity Alakurtti i Priladozh’ya. Moskva: Akademiya nauk USSR.
Krivovichev, V.G. (2008). Mineralogichesky slovar’. Sankt-Peterburg: Sankt-Peterburgskiy Universitet.
Lokka, L. (1928). Über Wiikit. Bulletin de la Comission Geologique de Finlande, (82), 68-84.
Lokka, L. (1950). Uranium Mineral Wiikite. On Wiikite in General and on Its Physical Properties. Bulletin de la Comission Geologique de Finlande, (149), 33-61.
Moiseev, B.M. (1985). Prirodnye radiatsionnye protsessy v mineralakh. Moskva: Nedra.
Nettleton, K.C.A., Nikoloski, A.N., & Da Costa, M. (2015). The Leaching of Uranium from Betafite. Hydrometallurgy, (157), 270-279.
Qiuxiang, C., Isakov, A.I., Xiaodong, L., Krivovichev, S.V., & Burakov, B.E. (2014). A Study of Natural Metamict Yttrium Niobate as an Analogue of an Actinide Ceramic Waste Form. Materials Research Society Proceedings, (1665), 313-318.
Rakov, L.T. (1989). Povedenie paramagnitnykh defectov pri ter-micheskom otzhige kvartsa. Kristallografiya, (34), 260-262.
Reed, S.J.B. (2005). Electron Microprobe Analysis and Scanning Electron Microscopy in Geology. Cambridge, London: University of Cambridge.
Soboleva, M.V., & Pudovkina, I.A. (1957). Mineraly urana. Moskva: Gosudarstvennoe nauchno-tekhnicheskoe izdatel’stvo literatury po geologii i okhrane nedr.