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Hydroxynatropyrochlore, (Na,Сa,Ce)2Nb2O6(OH), a new member of the pyrochlore group from the Kovdor phoscorite–carbonatite pipe, Kola Peninsula, Russia

  • Gregory Yu. Ivanyuk (a1), Victor N. Yakovenchuk (a1), Taras L. Panikorovskii (a1) (a2), Nataliya Konoplyova (a1), Yakov A. Pakhomovsky (a1), Ayya V. Bazai (a1), Vladimir N. Bocharov (a3) and Sergey V. Krivovichev (a1) (a2)...


Hydroxynatropyrochlore, (Na,Сa,Ce)2Nb2O6(OH), is a new Na–Nb–OH-dominant member of the pyrochlore supergroup from the Kovdor phoscorite–carbonatite pipe, Kola Peninsula, Russia. It is cubic, Fd $\bar{3}$ m, a = 10.3211(3) Å, V = 1099.46(8) Å3 and Z = 8 (from powder diffraction data) or a = 10.3276(5) Å, V = 1101.5(2) Å3 and Z = 8 (from single-crystal diffraction data). Hydroxynatropyrochlore is a characteristic accessory mineral of the low-carbonate phoscorite in the contact zone of the phoscorite–carbonatite pipe with host foidolite as well as in the carbonate-rich phoscorite and carbonatite of the pipe axial zone. It usually forms zonal cubic or cubooctahedral crystals (up to 0.5 mm in diameter) with irregularly shaped relics of amorphous U–Ta-rich hydroxykenopyrochlore inside. Characteristic associated minerals include rock-forming calcite, dolomite, forsterite, hydroxylapatite, magnetite and phlogopite, accessory baddeleyite, baryte, barytocalcite, chalcopyrite, chamosite–clinochlore, galena, gladiusite, juonniite, ilmenite, magnesite, pyrite, pyrrhotite, quintinite, spinel, strontianite, valleriite and zirconolite. Hydroxynatropyrochlore is pale brown, with an adamantine to greasy lustre and a white streak. The cleavage is average on {111} and the fracture is conchoidal. Mohs hardness is ~5. In transmitted light, the mineral is light brown, isotropic and n = 2.10(5) (λ = 589 nm). The calculated and measured densities are 4.77 and 4.60(5) g cm−3, respectively. The mean chemical composition determined by electron microprobe is: F 0.05, Na2O 7.97, CaO 10.38, TiO2 4.71, FeO 0.42, Nb2O5 56.44, Ce2O3 3.56, Ta2O5 4.73, ThO2 5.73, UO2 3.66, total 97.65 wt.%. The empirical formula calculated on the basis of Nb + Ta + Ti = 2 apfu is (Na1.02Ca0.73Ce0.09Th0.09 U0.05 ${\rm Fe}_{{\rm 0}{\rm. 02}}^{2 +} $ )Σ2.00(Nb1.68Ti0.23Ta0.09)Σ2.00O6.03(OH1.04F0.01)Σ1.05. The simplified formula is (Na,Ca,Ce)2Nb2O6(OH). The mineral dissolves slowly in hot HCl. The strongest X-ray powder-diffraction lines [listed as (d in Å)(I)(hkl)] are as follows: 5.96(47)(111), 3.110(30)(311), 2.580(100)(222), 2.368(19)(400), 1.9875(6)(333), 1.8257(25)(440) and 1.5561(14)(622). The crystal structure of hydroxynatropyrochlore was refined to R1 = 0.026 on the basis of 80 unique observed reflections. The mineral belongs to the pyrochlore structure type A2B2O6Y1 with octahedral framework of corner-sharing BO6 octahedra with A cations and OH groups in the interstices. The Raman spectrum of hydroxynatropyrochlore contains characteristic bands of the lattice, BO6, B–O and O–H vibrations and no characteristic bands of the H2O vibrations. Within the Kovdor phoscorite–carbonatite pipe, hydroxynatropyrochlore is the latest hydrothermal mineral of the pyrochlore supergroup, which forms external rims around grains of earlier U-rich hydroxykenopyrochlore and separated crystals in voids of dolomite carbonatite veins. The mineral is named in accordance with the pyrochlore supergroup nomenclature.


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Corresponding author: Sergey V. Krivovichev, Email:


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Associate Editor: G. Diego Gatta



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Andrade, M., Atencio, D., Persiano, A. and Ellena, J. (2013) Fluorcalciomicrolite, (Ca,Na,□)2Ta2O6F, a new microlite-group mineral from Volta Grande pegmatite, Nazareno, Minas Gerais, Brazil. Mineralogical Magazine, 77, 29892996.
Andrade, M., Atencio, D., Chukanov, N. and Ellena, J. (2015) Hydrokenomicrolite, (□,H2O)2Ta2(O,OH)6(H2O), a new microlite-group mineral from Volta Grande pegmatite, Nazareno, Minas Gerais, Brazil. American Mineralogist, 98, 292296.
Andrade, M.B., Yang, H., Atencio, D., Downs, R.T., Chukanov, N.V., Lemée-Cailleau, M.H., Persiano, A.I.C., Goeta, A.E. and Ellena, J. (2016) Hydroxycalciomicrolite, Ca1.5Ta2O6(OH), a new member of the microlite group from Volta Grande pegmatite, Nazareno, Minas Gerais, Brazil. Mineralogical Magazine, 81, 555564.
Atencio, D., Andrade, M.B., Christy, A.G., Gieré, R. and Kartashov, P.M. (2010) The pyrochlore supergroup of minerals nomenclature. The Canadian Mineralogist, 48, 673698.
Atencio, D., Ciriotti, M.E. and Andrade, M.B. (2013) Fluorcalcioroméite, (Ca,Na)2Sb5+2(O,OH)6F, a new roméite-group mineral from Starlera mine, Ferrera, Grischun, Switzerland: description and crystal structure. Mineralogical Magazine, 77, 467473.
Atencio, D., Andrade, M.B., Bastos Neto, A.C. and Pereira, V.P. (2017) Ralstonite renamed hydrokenoralstonite, coulsellite renamed fluornatrocoulsellite, and their incorporation into the pyrochlore supergroup. The Canadian Mineralogist, 55, 115120.
Bahfenne, S. and Frost, R.L. (2010) Raman spectroscopic study of the antimonate mineral roméite. Spectrochimica Acta A, 75, 637639.
Biagioni, C., Orlandi, P., Nestola, F. and Bianchin, S. (2013) Oxycalcioroméite, Ca2Sb2O6O, from Buca della Vena mine, Apuan Alps, Tuscany, Italy: a new member of the pyrochlore supergroup. Mineralogical Magazine, 77, 30273037.
Britvin, S.N., Dolivo-Dobrovolsky, D.V. and Krzhizhanovskaya, M.G. (2017) Software for processing of X-ray powder diffraction data obtained from the curved image plate detector of Rigaku RAXIS Rapid II diffractometer. Zapiski Rossiiskogo Mineralogicheskogo Obshestva, 146(3), 104107 [in Russian].
Bruker-AXS (2014) APEX2. Version 2014.11-0. Madison, Wisconsin, USA.
Christy, A.G. and Atencio, D. (2013) Clarification of status of species in the pyrochlore supergroup. Mineralogical Magazine, 77, 1320.
Epstein, E.M., Basmanov, V.N., Berezina, L.A., Gol'dfurt, T.L., Zhuravleva, L.N., Nechaeva, E.A., Sokolov, S.V. and Chernyshova, L.V. (1970) The appropriateness of allocation, the mineralogical and geochemical features and valuation of iron-phosphorus and rare-metal ores of the Kovdor deposit. Report about scientific works. Vol.1. Moscow, Russia (Archives of the Geological Institute of the Kola Science Centre of RAN) 217 pp. [in Russian].
Fan, G., Ge, X., Li, G., Yu, A. and Shen, G. (2016) Oxynatromicrolite, (Na,Ca,U)2Ta2O6(O,F), a new member of the pyrochlore supergroup from Guanpo, Henan Province, China. Mineralogical Magazine, 81, 743751.
Gargori, C., Galindo, R., Cerro, S., García, A., Llusar, M. and Monrós, G. (2010) Synthesis of a new CaxY2–xVxSn2–xO7 yellow pigment. Physics Procedia, 8, 8487.
Hålenius, U. and Bosi, F. (2013) Oxyplumboroméite, Pb2Sb2O7, a new mineral species of the pyrochlore supergroup from Harstigen mine, Värmland, Sweden. Mineralogical Magazine, 77, 29312939.
Ivanyuk, G.Yu., Yakovenchuk, V.N. and Pakhomovsky, Ya.A. (2002) Kovdor. Laplandia Minerals, Apatity, 326 pp.
Ivanyuk, G.Yu., Kalashnikov, A.O., Pakhomovsky, Ya.A., Mikhailova, J.A., Yakovenchuk, V.N., Konopleva, N.G., Sokharev, V.A., Bazai, A.V. and Goryainov, P.M. (2016) Economic minerals of the Kovdor baddeleyite-apatite-magnetite deposit, Russia: mineralogy, spatial distribution, and ore processing optimization. Ore Geology Reviews, 77, 279311.
Ivanyuk, G.Y., Yakovenchuk, V.N., Panikorovskii, T.L., Konoplyova, N., Pakhomovsky, Y.A., Bazai, A.V., Bocharov, V.N. and Krivovichev, S.V. (2017) Hydroxynatropyrochlore, IMA 2017-074. CNMNC Newsletter No. 40, December 2017, page 1580; Mineralogical Magazine, 81, 15771581.
Jingwu, Y., Li, G., Guangming, Y., Ge, X., Xu, H. and Wang, J. (2015) Fluornatropyrochlore, a new pyrochlore supergroup mineral from the Boziguoer rare earth element deposit, Baicheng County, Akesu, Xinjiang, China. The Canadian Mineralogist, 53, 455460.
Kalashnikov, A.O., Yakovenchuk, V.N., Pakhomovsky, Y.A., Bazai, A.V., Sokharev, V.A., Konopleva, N.G., Mikhailova, J.A., Goryainov, P.M. and Ivanyuk, G.Yu. (2016) Scandium of the Kovdor baddeleyite–apatite–magnetite deposit (Murmansk Region, Russia): Mineralogy, spatial distribution, and potential resource. Ore Geology Reviews, 72, 532537.
Li, G., Yang, G., Lu, F., Xiong, M., Ge, X., Pan, B. and de Fourestier, J. (2016) Fluorcalciopyrochlore, a new mineral species from Bayan Obo, Inner Mongolia, P.R. China. The Canadian Mineralogist, 54, 12851291.
Mączka, M., Knyazev, A.V., Kuznetsova, N.Yu., Ptak, M. and Macalik, L. (2011) Raman and IR studies of TaWO5.5, ASbWO6 (A = K, Rb, Cs, Tl) and ASbWO6·H2O (A = H, NH4, Li, Na) pyrochlore oxides. Journal of Raman Spectroscopy, 42, 529533.
Mandarino, J.A. (1981) The Gladstone – Dale relationship: Part IV. The compatibility concept and its application. The Canadian Mineralogist, 19, 441450.
Mikhailova, J.A., Kalashnikov, A.O., Sokharev, V.A., Pakhomovsky, Y.A., Konopleva, N.G., Yakovenchuk, V.N., Bazai, A.V., Goryainov, P.M. and Ivanyuk, G.Y. (2016) 3D mineralogical mapping of the Kovdor phoscorite–carbonatite complex (Russia). Mineralium Deposita, 51, 131149.
Mills, S.J., Christy, A.G., Kampf, A.R., Birch, W.D. and Kasatkin, A. (2017) Hydroxykenoelsmoreite, the first new mineral from the Republic of Burundi. European Journal of Mineralogy, 29, 491497.
Miyawaki, R., Momma, K., Matsubara, S., Sano, T., Shigeoka, M. and Horiuchi, H. (2017) Hydroxykenopyrochlore, IMA 2017-030a. CNMNC Newsletter No. 39, October 2017. Mineralogical Magazine, 81, 1285.
Momma, K. and Izumi, F. (2011) VESTA 3 for three-dimensional visualization of crystal, volumetric and morphology data. Journal of Applied Crystallography, 44, 12721276.
Rodionov, N.V., Belyatsky, B.V., Antonov, A.V., Kapitonov, I.N. and Sergeev, S.A. (2012) Comparative in-situ U–Th–Pb geochronology and trace element composition of baddeleyite and low-U zircon from carbonatites of the Palaeozoic Kovdor alkaline–ultramafic complex, Kola Peninsula, Russia. Gondwana Research, 21, 728744.
Sheldrick, G.M. (2008) A short history of SHELX. Acta Crystallographica, A64, 112122.
Subbotin, V.V. and Subbotina, G.F. (2000) Minerals of the pyrochlore group in phoscorites and carbonatites of the Kola Peninsula. Vestnik MGTU, 3(2), 273284 [in Russian].
Yakovenchuk, V.N., Ivanyuk, G.Yu., Pakhomovsky, Ya.A. and Men'shikov, Yu.P. (2005) Khibiny. Laplandia Minerals, Apatity, 2005. 468 pp.
Yakovenchuk, V.N., Ivanyuk, G.Y., Pakhomovsky, Y.A., Panikorovskii, T.L., Britvin, S.N., Krivovichev, S.K., Shilovskikh, V.V. and Bocharov, V.N. (2018) Kampelite, Ba3Mg1.5Sc4(PO4)6(OH)3·4H2O, a new very complex Ba-Sc phosphate mineral from the Kovdor phoscorite-carbonatite complex (Kola Peninsula, Russia). Mineralogy and Petrology, 112, 111112.
Witzke, T., Steins, M., Doering, T., Schuckmann, W., Wegner, R. and Pöllmann, H. (2011). Fluornatromicrolite, (Na,Ca,Bi)2Ta2O6F, a new mineral species from Quixaba, Paraiba, Brazil. The Canadian Mineralogist, 49, 11051110.
Yang, G., Li, G., Xiong, M., Pan, B. and Yan, C. (2014) Hydroxycalciopyrochlore, a new mineral species from Sichuan, China. Acta Geologica Sinica, English Edition, 88, 748753.
Yin, J., Li, G., Yang, G., Ge, X., Xu, H. and Wang, J. (2015) Fluornatropyrochlore, a new pyrochlore supergroup mineral from the Boziguoer rare earth element deposit, Baicheng county, Akesu, Xinjiang, China. The Canadian Mineralogist, 53, 455460.


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