Quick Search:    advanced search

GSW Home   GeoRef Home   My GSW Alerts   Contact GSW   About GSW   Journals List   Help

This Article Figures Only Full Text Full Text (PDF) Supplementary Data Info Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Grew, E. S. Articles by Carson, C. J. Search for Related Content GeoRef GeoRef Citation

Stornesite-(Y), (Y, Ca)₂Na₆(Ca,Na)₈(Mg,Fe)₄₃(PO₄)₃₆, the first terrestrial Mg-dominant member of the fillowite group, from granulite-facies paragneiss in the Larsemann Hills, Prydz Bay, East Antarctica

¹ Department of Earth Sciences, University of Maine, 5790 Bryand Research Center, Orono, Maine 04469-5790, U.S.A.
² Laboratorium für chemische und mineralogische Kristallographie, Universität Bern, Freiestrasse 3, CH-3012 Bern, Switzerland
³ Institut für Geowissenschaften/Mineralogie, Ruhr-Universität Bochum, D-44780 Bochum, Germany
⁴ Geoscience Australia, GPO Box 378, Canberra ACT 2601, Australia

Correspondence: ^* E-mail: esgrew{at}maine.edu

Stornesite-(Y), end-member formula Y₂Na₆(Ca₅Na₃)Mg₄₃(PO₄)₃₆, is a new Y-dominant analog of the meteoritic mineral chladniite. A representative electron microprobe analysis is SiO₂ = 0.02, P₂O₅ = 48.11, SO₃ = 0.05, MgO = 23.16, MnO = 0.24, FeO = 15.55, Na₂O = 5.04, CaO = 5.66, SrO = 0.02, Y₂O₃ = 1.43, Yb₂O₃ = 0.24, UO₂ = 0.01, Sum = 99.53 wt%, which gives Y_0.68Yb_0.06Na_8.69Ca_5.40Sr_0.01Mg_30.71Fe_11.56 Mn_0.18Si_0.02S_0.04P_36.22O₁₄₄. Overall, Y + REE range from 0.542 to 0.985 atoms per formula, and atomic Mg/(Mg + Fe) ratio from 0.684 to 0.749. Single-crystal X-ray diffraction gives trigonal symmetry, R, a = 14.9628(27) Å, c = 42.756(11) Å, V = 8290(4) ų, calculated density = 3.196 g/cm³, Z = 3. The mineral is isostructural with synthetic chladniite, but the (0, 0, 0) site is dominantly occupied by Y instead of Ca. Bond lengths are considerably shorter than for Ca sites; Y and Yb are fully ordered at this site, which is our rationale for recognizing stornesite-(Y) as a distinct species. The strongest lines in the powder pattern [d in Å, (I), (hkl)] are 3.67 (40) (0 3 6, 3 0 6), 3.52 (40) (0 0 12, 3 1 2, 1 3 ), 2.94 (60) (0 1 14, 3 2 , 2 3 2), 2.73 (100) (2 0 14, 0 3 12, 3 0 12), 1.84 (40) (1 5 14, 5 1 , 0 6 12, 6 0 12). The mineral is optically uniaxial +, n = 1.6215(10) and n = 1.6250(10) at 589 nm. Its color is pale yellow in standard thin sections. Stornesite-(Y) is found as inclusions in fluorapatite nodules in two paragneiss specimens from Johnston Fjord, Stornes Peninsula (whence the name) and in a third from Brattnevet, Larsemann Hills. Associated minerals are wagnerite, xenotime-(Y), monazite-(Ce), P-bearing K-feldspar, biotite, sillimanite, quartz, and pyrite; it is commonly altered to rusty material and secondary phosphates. Grains are anhedral, subhedral, or locally euhedral with hexagonal or rhombic outlines; maximum dimensions are 1 x 0.25 mm. It is inferred to have formed at 800–860 °C, 6–7 kbar by reaction of biotite with an anatectic melt locally enriched in P by interaction with fluorapatite.

Key Words: Phosphate • new mineral • Antarctica • Larsemann Hills • electron microprobe • crystal structure • granulite facies • anatexis

This article has been cited by other articles:

				E. S. Grew, M. G. Yates, R. J. Beane, C. Floss, and C. Gerbi Chopinite-sarcopside solid solution, [(Mg,Fe)3{square}](PO4)2, in GRA95209, a transitional acapulcoite: Implications for phosphate genesis in meteorites American Mineralogist, February 1, 2010; 95(2-3): 260 - 272. [Abstract] [Full Text] [PDF]

				F. Hatert and E. A.J. Burke THE IMA-CNMNC DOMINANT-CONSTITUENT RULE REVISITED AND EXTENDED Can Mineral, June 1, 2008; 46(3): 717 - 728. [Abstract] [Full Text] [PDF]

				E. S. Grew, H. A. Graetsch, B. Poter, M. G. Yates, I. Buick, H.-J. Bernhardt, W. Schreyer, G. Werding, C. J. Carson, and G. L. Clarke Boralsilite, Al16B6Si2O37, and "boron-mullite:" Compositional variations and associated phases in experiment and nature American Mineralogist, February 1, 2008; 93(2-3): 283 - 299. [Abstract] [Full Text] [PDF]

				E. S. Grew, T. Armbruster, O. Medenbach, M. G. Yates, and C. J. Carson TASSIEITE, (Na,{square})Ca2(Mg,Fe2+,Fe3+)2(Fe3+,Mg)2(Fe2+,Mg)2(PO4)6{middle dot}2H2O, A NEW HYDROTHERMAL WICKSITE-GROUP MINERAL IN FLUORAPATITE NODULES FROM GRANULITE-FACIES PARAGNEISS IN THE LARSEMANN HILLS, PRYDZ BAY, EAST ANTARCTICA Can Mineral, April 1, 2007; 45(2): 293 - 305. [Abstract] [Full Text] [PDF]

				D. E. Harlov, H. R. Marschall, and M. Hanel Fluorapatite-monazite relationships in granulite-facies metapelites, Schwarzwald, southwest Germany Mineralogical Magazine, April 1, 2007; 71(2): 223 - 234. [Abstract] [Full Text] [PDF]

				E. S. Grew, T. Armbruster, O. Medenbach, M. G. Yates, and C. J. Carson Chopinite, [(Mg, Fe)3{square}](PO4)2, a new mineral isostructural with sarcopside, from a fluorapatite segregation in granulite-facies paragneiss, Larsemann Hills, Prydz Bay, East Antarctica European Journal of Mineralogy, March 1, 2007; 19(2): 229 - 245. [Abstract] [Full Text] [PDF]