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Natrotitanite, ideally (Na0.5Y0.5)Ti(SiO4)O, a new mineral from the Verkhnee Espe deposit, Akjailyautas mountains, Eastern Kazakhstan district, Kazakhstan: description and crystal structure

Published online by Cambridge University Press:  05 July 2018

A. V. Stepanov ,
G. K. Bekenova ,
V. L. Levin  and
F. C. Hawthorne
A. V. Stepanov
Affiliation:
Satpaev Institute of Geological Sciences, ul. Kabanbai batyr 69, Almaty 050010, Kazakhstan
G. K. Bekenova
Affiliation:
Satpaev Institute of Geological Sciences, ul. Kabanbai batyr 69, Almaty 050010, Kazakhstan
V. L. Levin
Affiliation:
Satpaev Institute of Geological Sciences, ul. Kabanbai batyr 69, Almaty 050010, Kazakhstan
F. C. Hawthorne*
Affiliation:
Satpaev Institute of Geological Sciences, ul. Kabanbai batyr 69, Almaty 050010, Kazakhstan Department of Geological Sciences, University of Manitoba, Winnipeg, Manitoba R3T 2N2, Canada
*
*E-mail: [email protected]
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Abstract

Natrotitanite, ideally (Na0.5Y0.5)Ti(SiO4)O, is a new mineral from the Verkhnee Espe rare-element deposit at the northern exo-contact of the Akjailyautas granite massif in the northern part of the Tarbagatai mountain range, Eastern Kazakhstan. Both the mineral and the name have been approved by the Commission on New Minerals, Nomenclature and Classification of the International Mineralogical Association (IMA 2010-033). Star-shaped aggregates of small short prisms of yellow or yellowish white (Na,Y,REE)-bearing titanite rimmed by thin (∼2 μm) rims of natrotitanite are embedded in yttrium-bearing fluorite and replace narsarsukite. Associated minerals are microcline, albite, quartz, riebeckite, aegirine, biotite, astrophyllite, rutile, zircon and elpidite. Natrotitanite is milky white to yellowish grey, transparent to translucent, and has a white streak and a vitreous lustre. It shows pale orange cathodoluminescence but does not fluoresce under ultraviolet light. It shows no cleavage or parting, and is brittle; the calculated density is 3.833 g cm–3. The indices of refraction, measured with the Bloss spindle stage for the wavelength 590 nm using a gel filter, are α = 1.904, γ = 2.030, and these values are in accord with the mean refractive index, 1.988, calculated from the Gladstone-Dale relation. Natrotitanite is monoclinic, C2/c, a = 6.5691(2), b = 8.6869(3), c = 7.0924(2) Å, β = 114.1269(4)°, V = 369.4(2) Å3, Z = 4, a:b:c = 0.7562:1: 0.8164. The seven strongest lines in the X-ray powder diffraction pattern [in the order d (Å), I, (hkl)] are as follows: 2.597, 10, (130); 3.248, 8, (11); 2.994, 6, (200); 1.641, 4, (330); 4.941, 3, (110); 1.498, 3, (400); 2.273, 3, (11). Chemical analysis by electron microprobe gave Nb2O5 1.28, SiO2 27.83, TiO2 35.00, SnO2 0.57, V2O3 0.36, Fe2O3 0.23, Y2O3 7.87, Ce2O3 0.83, Sm2O3 0.26, Gd2O3 0.46, Tb2O3 0.17, Dy2O3 2.45, Ho2O3 0.16, Er2O3 2.24, Tm2O3 0.50, Yb2O3 2.53, Nd2O3 0.35, Lu2O3 0.28, MnO 0.33, CaO 8.16, Na2O 5.55, F 1.52 O ≡ F –0.64, sum 98.71 wt.%. The resulting empirical formula is (Na0.39Ca0.32Y0.15Dy0.03Yb0.03Er0.03Ce0.01Ho0.01Tm0.01Gd0.01Nd0.01)Σ1.00(Ti0.95Nb0.02Sn0.01Fe3+0.01Mn0.01V0.01)Σ1.01Si1.01O4.00(O0.83F0.17), calculated on the basis of 3 cations per formula unit. The general formula is written as (Na,Ca,Y,REE)TiSiO4(O,F), and the endmember formula is (Na0.5Y0.5)Ti(SiO4)O.

The crystal structure of a composite optically continuous crystal of natrotitanite and (Na, Y)-bearing titanite was mounted on a Bruker D8 three-circle diffractometer equipped with a rotating anode generator (MoKα radiation), a multi-layer optics incident-beam path and an APEX-II CCD detector. The crystal structure was refined in space group C2/c to a final R1 index of 1.8%. Natrotitanite is isostructural with titanite, (Na + Y + REE) replacing Ca at the Ca site in the titanite structure.

Keywords

Natrotitanitenew mineraltitanitecrystal-structure refinementelectron-microprobe analysisoptical propertiesVerkhnee Espe depositKazakhstan
Type
Research Article
Information
Mineralogical Magazine , Volume 76 , Issue 1 , February 2012 , pp. 37 - 44
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 2012

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References

Burns, P.C. and Hawthorne, F.C. (1995) The crystal structure of sinkankasite, a complex heteropolyhedral sheet mineral. American Mineralogist, 80, 620–627.CrossRefGoogle Scholar
Černý, P., Novak, M. and Chapman, R. (1995) The Al(Nb,Ta)Ti-2 substitution in titanite: the emergence of a new species? Mineralogy and Petrology, 52, 61–73.Google Scholar
Chakhmouradian, A.R. (2004) Crystal chemistry and paragenesis of compositionally-unique (Al-, Fe-, Nb-, and Zr-rich) titanite from Afrikanda, Russia. American Mineralogist, 89, 1752–1762.CrossRefGoogle Scholar
Chakhmouradian, A.R. and Zaitsev, A.N. (2002) Calcite-amphibole-clinopyroxene from the Afrikanda Complex, Kola Peninsula, Russia: mineralogy and a possible link to carbonatites II Silicate I. minerals. The Canadian Mineralogist, 40, 1347–1374.CrossRefGoogle Scholar
Groat, L.A., Raudsepp, M., Hawthorne, F.C., Ercit, T.S., Sherriff, B.L. and Hartman, J.S. (1990) The amblygonite-montebrasite series: characterization by single-crystal structure refinement, infrared spectroscopy and multinuclear MAS-NMR spectroscopy. American Mineralogist, 75, 992–1008.Google Scholar
Hawthorne, F.C. (2002) The use of end-member chargearrangements in defining new mineral species and heterovalent substitutions in complex minerals. The Canadian Mineralogist, 40, 699–710.CrossRefGoogle Scholar
Hawthorne, F.C., Groat, L.A., Raudsepp, M. and Ercit, T.S. (1987) Kieserite, Mg(SO4)(H2O), a titanitegroup mineral. Neues Jahrbuch für Mineralogie Abhandlungen, 157, 121–132.Google Scholar
Hawthorne, F.C, Groat, L.A., Raudsepp, M., Ball, N.A., Kimata, M., Spike, F.D., Gaba, R., Halden, N.M., Lumpkin, G.R., Ewing, R.C., Greegor, R.B., Lytle, F.W., Ercit, T.S., Rossman, G.R., Wicks, F.J., Ramik, R.A., Sherriff, B.L., Fleet, M.E. and McCammon, C. (1991) Alpha-decay damage in titanite. American Mineralogist, 76, 370–396.Google Scholar
Hawthorne, F.C, Ungaretti, L. and Oberti, R. (1995) Site populations in minerals: terminology and presentation of results of crystal-structure refinement. The Canadian Mineralogist, 33, 907–911.Google Scholar
Higgins, J.B. and Ribbe, P.H. (1976) The crystal chemistry and space groups of natural and synthetic titanites. American Mineralogist, 61, 878–888.Google Scholar
Hughes, J.M., Bloodaxe, E.S., Hanchar, J.M. and Foord, E.E. (1997) Incorporation of rare earth elements in titanite: stabilization of the A2/a dimorph by creation of antiphase boundaries. American Mineralogist, 82, 512–516.CrossRefGoogle Scholar
Liferovich, R.P. and Mitchell, R.H. (2005) Composition and paragenesis of Na-, Nb-and Zr-bearing titanite from Khibina, Russia, and crystal-structure data for synthetic analogues. The Canadian Mineralogist, 43, 795–812.CrossRefGoogle Scholar
Liferovich, R.P. and Mitchell, R.H. (2006) Tantalumbearing titanite: synthesis and crystal structure data. Physics and Chemistry of Minerals, 33, 73–83.CrossRefGoogle Scholar
Lussier, A.J., Cooper, M.A., Hawthorne, F.C. and Kristiansen, R. (2009) Triclinic titanite from the Heftetjern granitic pegmatite, Tørdal, southern Norway. Mineralogical Magazine, 73, 709–722.CrossRefGoogle Scholar
Mongiorgi, R. and Riva Di Sanseverino, L.R. (1968) A reconsideration of the structure of titanite, CaTiOSiO4. Mineralogica et Petrographica Acta, 14, 123–141.Google Scholar
Moore, P.B. (1970) Structural hierarchies among minerals containing octahedrally coordinating oxygen. Neues Jahrbuch für Mineralogie Monatshefte, 1970, 163–173.Google Scholar
Moore, P.B. and Araki, T. (1974) Jahnsite, CaMn2+Mg2(H2O)8Fe3+ 2 (OH)2[PO4]4: a novel stereoisomerism of ligands about octahedral corner-sharing chains. American Mineralogist, 59, 964–973.Google Scholar
Oberti, R., Rossi, G. and Smith, D.C. (1985) X-ray crystal structure refinement studies of the TiO $ Al(OH,F) exchange in high-aluminum sphenes. Terra Cognita, 5, 428 (abstract).Google Scholar
Oberti, R. Smith, D.C., Rossi, G. and Caucia, F. (1991) The crystal-chemistry of high-aluminium titanites. European Journal of Mineralogy, 3, 777–792.CrossRefGoogle Scholar
Ribbe, P.H. (1980) Titanite. Pp. 137–154. in: Orthosilicates (Ribbe, P.H., editor). Reviews in Mineralogy, 5. Mineralogical Society of America, Washington DC.Google Scholar
Robinson, P.D., Sen Gupta, P.K., Swihart, G.H. and Houk, L. (1992) Crystal structure, H positions, and the Se lone pair of synthetic chalcomenite, Cu(H2O)2(SeO3). American Mineralogist, 77, 834–838.Google Scholar
Sheldrick, G.M. (2008) A short history of SHELX. Acta Crystallographica, A64, 112–122.CrossRefGoogle Scholar
Speer, J.A. and Gibbs, G.V. (1976) The crystal structure of synthetic titanite, CaTiOSiO4, and the domain textures of natural titanites. American Mineralogist, 61, 238–247.Google Scholar
Stepanov, A.V. and Bekenova, G.K. (2009) Brief description of the Verkhnee Espe rare-element deposit. Proceedings of an international conference on geology, mineralogy and future trends of mineral resources development. Almaty, Kazakhstan, 248–258.Google Scholar
Süsse, P. (1975) Structure and crystal chemistry of slavikite, NaMg2Fe5(SO4)7(OH)6·33H2O. Neues Jahrbuch für Mineralogie Monatshefte, 1975, 27–40.Google Scholar
Taylor, M. and Brown, G.E. (1976) High-temperature structural study of the P21/a > A2/a phase transitions in synthetic titanite, CaTiSiO5 . American Mineralogist, 61, 435–447.Google Scholar
Zachariasen, W.H. (1930) The crystal structure of titanite. Zeitschrift für Kristallographie, 73, 7–17.Google Scholar
Zemann, A. and Zemann, J. (1962) Die Kristallstruktur von TeiniEint. Beispiel für die Korrektur einer chemischen Formel auf Grund der strukturbestimmung. Acta Crystallographica, 15, 698–702.CrossRefGoogle Scholar