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Barrydawsonite-(Y), Na1.5CaY0.5Si3O9H: a new pyroxenoid of the pectolite–serandite group

Published online by Cambridge University Press:  02 January 2018

R. H. Mitchell ,
M. D. Welch ,
A. R. Kampf ,
A. K. Chakhmouradian  and
J. Spratt
R. H. Mitchell*
Affiliation:
Department of Geology, Lakehead University, Thunder Bay, Ontario, Canada P7B 5E1
M. D. Welch
Affiliation:
Department of Earth Sciences, The Natural History Museum, Cromwell Road, London SW7 5BD, UK
A. R. Kampf
Affiliation:
Mineral Sciences Department, Natural History Museum of Los Angeles County, 900 Exposition Boulevard, Los Angeles, CA 90007, USA
A. K. Chakhmouradian
Affiliation:
Department of Geological Sciences, University of Manitoba, Winnipeg, Manitoba, Canada R3T 2N2
J. Spratt
Affiliation:
Department of Earth Sciences, The Natural History Museum, Cromwell Road, London SW7 5BD, UK
*
*E-mail: [email protected]
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Abstract

The new pyroxenoid barrydawsonite-(Y) occurs at the Merlot Claim, North Red Wine Pluton, Labrador, Canada (62°32'38.54'' W; 54°08'1.37'' N). The host rock is a metamorphosed eudialyte syenite consisting of eudialyte, potassic arfvedsonite, jadeitic aegirine, nepheline, albite and potassium feldspar with accessory Y-bearing pectolite, britholite and steenstrupine. Barrydawsonite-(Y) crystals commonly have discrete thin rims of Y-bearing pectolite. The average empirical formula (based on nine anions p.f.u.) is Na1.54Ca0.74Mn0.15Fe0.07Y0.38Nd0.01Sm0.01Gd0.02Tb0.01Dy0.04Ho0.01Er0.02Yb0.01Si3.00O9H. The simplified formula is Na1.5Y0.5CaSi3O9H. Barrydawsonite-(Y) is related to pectolite by the substitution ½[NaM3+Ca–2] (M3+ = Y,REE), and is exceptional in being the only member of the pectolite group that has the structure of the monoclinic M2abc polytype. The crystal structure has been determined in monoclinic space group P21/a: a = 15.5026(2), b = 7.0233(1), c = 6.9769(1) Å, β = 95.149(1)°, V = 756.58(2) Å3(Z = 4). Final agreement indices are R1 = 0.038, wR2 = 0.068, Goof = 1.136. The asymmetric unit of barrydawsonite-(Y) has three metal sites: M(1) = Ca, M(2) = Na0.5(Y,REE)0.5, M(3) = Na. M(1) and M(2) are octahedrally-coordinated sites, whereas M(3) is [8]-coordinated as in pectolite and serandite. The structural formula for the empirical composition is M(3)Na1.00M(2)(Na0.50Y0.38REE0.13)Σ=1.01M(1)(Na0.04Ca0.74Mn0.152+Fe0.072+)Σ=1.00Si3O9H. There is excellent agreement between the refined site-scattering values and those calculated based upon the structural formula.

Barrydawsonite-(Y) is biaxial (+) with α = 1.612(1), β = 1.617(1), γ = 1.630(1) (white light) and 2V = 63(1)°. The five strongest peaks in the X-ray powder diffraction pattern are [dobs (Å), Iobs%, (hkl)]: [2.905, 100, (023)], [3.094, 30, (210,211,121,202)], [1.7613, 29, (127,323,040)], [3.272, 27, (202,104)], [1.7016, 27, (140,227,325)].

Keywords

barrydawsonite-(Y)pyroxenoidpectolite–seranditepolytype
Type
Research Article
Information
Mineralogical Magazine , Volume 79 , Issue 3 , June 2015 , pp. 671 - 686
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 2015

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References

Arakcheeva, A., Pattison, P., Meisser, N., Chapuis, G., Pekov, I. and Thélin, P. (2007) New insight into the pectolite-serandite series: a single crystal diffraction study of Na(Ca1.73Mn0.27)[HSi3O9] at 293 and 100 K. Zeitschrift für Kristallographie, 222, 696–704.Google Scholar
Belokoneva, E.I., Sandomirski, P.A. and Simonov, M.A (1974) Crystal structure of cadmium pectolite. Soviet Physics Doklady, 18, 629–630. [Russian].Google Scholar
Brown, I.D. and Altermatt, D.A. (1985) Bond-valence parameters obtained from a systematic analysis of the Inorganic Crystal Structure Database. Acta Crystallographica, B41, 244–247.CrossRefGoogle Scholar
Curtis, L.W. and Currie, K.L. (1981) Geology and petrology of the Red Wine alkaline complex, central Labrador. Geological Survey of Canada, Bulletin, 294, pp. 61.Google Scholar
Farrugia, L.J. (1999) WinGX: An integrated system of Windows Programs for the solution, refinement and analysis of single-crystal X-ray diffraction data. Journal of Applied Crystallography, 32, 837–838.CrossRefGoogle Scholar
Frost, R.L., Mahendran, M. and Poologanathan, K. and Xi, Y. (2012) Raman spectroscopic study of the mineral xonotlite Ca6Si6O17(OH)2-a component of plaster boards. Materials Research Bulletin, 47, 3644–3649.CrossRefGoogle Scholar
Groat, L.A. (1998) The crystal structure of gerenite-(Y), (Ca,Na)2(Y,REE)3Si6O18·2H2O, a cyclosilicate mineral. The Canadian Mineralogist, 36, 801–808.Google Scholar
Hammer, M.F., Libowitzky, E. and Rossmann, G.R. (1998) Single-crystal IR spectroscopy of very strong hydrogen bonds in pectolite, NaCa2[Si3O8(OH)], and serandi t e , NaMn2[Si3O8(OH)]. American Mineralogist, 83, 569–576.CrossRefGoogle Scholar
Henmi, C., Kawahara, A. and Henmi, K. (1983) The 3T, 4T and 5T polytypes of wollastonite from Kushiro, Hiroshima Prefectur e , Japan. American Mineralogist, 68, 156–163.Google Scholar
Jacobsen, S.D., Smyth, J.R., Swope, R.J. and Sheldon, R.I. (2000) Two proton positions in the very strong hydrogen bond of serandite, NaMn2[Si3O8(OH)]. American Mineralogist, 85, 745–752.CrossRefGoogle Scholar
Kerr, A. (2011) Rare earth element (REE) mineralization in Labrador: A review of known environments and the geological context of current exploration activity. Current Research, Newfoundland and Labrador Department of Natural Resources, Geological Survey, Report 11-1. 109–143.Google Scholar
Liebau, F. (1980) The role of cationic hydrogen in pyroxenoid crystal chemistry. American Mineralogist, 65, 981–985.Google Scholar
Mellini, M. and Merlino, S. (1982) The crystal structure of cascandite, CaScSi3O9H. American Mineralogist, 67, 604–609.Google Scholar
Müller, W.F. (1976) On stacking disorder and polytypism in pectolite and serandite. Zeitschrift für Kristallographie, 144, 401–408.CrossRefGoogle Scholar
Prewitt, C.T. (1967) Refinement of the crystal structure of pectolite, Ca2NaHSi3O9. Zeitschrift für Kristallographie, 125, 298–316.CrossRefGoogle Scholar
Robinson, K., Gibbs, G.V. and Ribbe, P.H. (1971) Quadratic elongation: A quantitative measure of distortion in coordination polyhedral. Science, 172, 567–570.CrossRefGoogle Scholar
Sheldrick, G.M. (2008) A short history of SHELX. Acta Crystallographica, A64, 112–122.CrossRefGoogle Scholar
Thomas, A. (1981) Geology along the southwestern margin of the Central Mineral Belt. Newfoundland and Labrador Department of Energy and Mines, Mineral Development Division, Report 81-4. pp. 40.Google Scholar
Wilson, A.J.C. (editor) (1992) International Tables for Crystallography. Volume C: Mathematical, Physical and Chemical Tables. Kluwer Academic Publishers, Dordrecht, The Netherlands.Google Scholar
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