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Polyhedral serpentine: a spherical analogue of polygonal serpentine?

Published online by Cambridge University Press:  05 July 2018

G. Cressey ,
B. A. Cressey  and
F. J. Wicks
G. Cressey*
Affiliation:
Department of Mineralogy, Natural History Museum, Cromwell Road, London SW7 5BD, UK
B. A. Cressey
Affiliation:
Electron Microscopy Centre, School of Chemistry, University of Southampton, Southampton SO17 1BJ, UK
F. J. Wicks
Affiliation:
Natural History Department, Royal Ontario Museum, 100 Queen’s Park, Toronto M5S 2C6, Canada
*
*E-mail: g.cressey@nhm.ac.uk
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Abstract

Vugs in late hydrothermal veins in the serpentinite at Gew-graze, Lizard, Cornwall, UK, contain serpentine spheres ≤0.7 mm in diameter composed of a crystallographically controlled radial array of well crystallized lizardite-1T crystals. Examinations with optical and scanning electron microscopy reveal that the spheres actually have polyhedral morphology. The polyhedral facets at the sphere surface are the (0001) terminations of individual single crystals of lizardite. Each lizardite crystal is a hexagonal prism and tapers inwards to the core. The angle from prism axis to prism axis is always ∼24°, and this angle is consistent even though individual prisms have not maintained contact during growth. The space between prisms is filled by smaller crystals of lizardite in more random orientations, forming a solid sphere. Collectively, the tapering prisms form a growth array that produces a surface tessellation consisting of mainly 6-fold neighbours, but with some 5-fold arrangements to accommodate a closed spherical structure. A ‘buckybalF, modified by adding face-centring points to each hexagon and pentagon, provides a useful model to describe the space filling adopted by the polyhedral lizardite spheres. Cross sections (close to an equatorial plane) through these polyhedral spheres resemble cross sections of polygonal serpentine, with 15 sectors at 24° to each other, though very much larger in diameter.

Keywords

serpentinepolyhedralpolygonalLizardUK
Type
Research Article
Information
Mineralogical Magazine , Volume 72 , Issue 6 , December 2008 , pp. 1229 - 1242
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 2008

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References

Andreani, M., Mevel, C. Boullier, A.-M. and Escartin, J. (2007) Dynamic control on serpentine crystallization in veins: Constraints on hydration processes in oceanic peridotites. Geochemistry Geophysics Geosystems, 8, Q020 1 2, doi: 1 0 . 1 029/ 2006GC001373.CrossRefGoogle Scholar
Andreani, M., Grauby, O., Baronnet, A. and Munoz, M. (2008) Occurrence, composition and growth of polyhedral serpentine. European Journal of Mineralogy, 20, 159–171.CrossRefGoogle Scholar
Baronnet, A. and Devouard, B. (2005) Microstructures of common polygonal serpentines from axial HRTEM imaging, electron diffraction and lattice-simulation data. The Canadian Mineralogist, 43, 513–542.CrossRefGoogle Scholar
Baronnet, A., Andreani, M., Grauby, O., Devouard, B., Nitsche, S. and Chaudanson, D. (2007) Onion morphology and micro structure of polyhedral serpentine. American Mineralogist, 92, 687–690.CrossRefGoogle Scholar
Batchelder, M. and Cressey, G. (1998) Rapid accurate phase quantification of clay-bearing samples using a position-sensitive X-ray detector. Clays and Clay Minerals, 46, 183–194.CrossRefGoogle Scholar
Cressey, G. and Schofield, P.F. (1996) Rapid whole-pattern profile stripping method for the quantification of multiphase samples. Powder Diffraction, 11, 35–39.CrossRefGoogle Scholar
Cressey, B.A. and Whittaker, EJ.W. (1993) Five-fold symmetry in chrysotile asbestos revealed by transmission electron microscopy. Mineralogical Magazine, 57, 729–732.CrossRefGoogle Scholar
Cressey, B.A. and Zussman, J. (1976) Electron microscopic studies of serpentinites. The Canadian Mineralogist, 14, 307–313.Google Scholar
Cressey, G., Spratt, J. and Cressey, B.A. (1993) Electron and X-ray petrography of an unusual serpentine from the Tilly Foster mine, Brewster, New York. The Canadian Mineralogist, 31, 447–458.CrossRefGoogle Scholar
Cressey, G., Cressey, B.A. and Wicks, FJ. (2008) The significance of the aluminium content of a lizardite at the nanoscale: the role of clinochlore as an aluminium sink. Mineralogical Magazine, 72, 817–825.CrossRefGoogle Scholar
Kroto, H.W., Heath, J.R., O'Brien, S., Curl, R.F. and Smalley, R.E. (1985) C60: Buckminsterfullerene Nature, 318, 162–163.CrossRefGoogle Scholar
Mellini, M. and Viti, C. (1994) Crystal structure of lizardite-1T from Elba, Italy. American Mineralogist, 79, 1194–1198.Google Scholar
Mellini, M. and Zanazzi,P.F (1987) Crystal structure of lizardite-ir and lizardite-2H from Coli, Italy American Mineralogist, 72, 943–948.Google Scholar
Mitchell, R.H. and Putnis, A. (1988) Polygonal serpentine in segregation-textured kimberlite. The Canadian Mineralogist, 26, 991–997.Google Scholar
Papp, G. (1988) Mineralogical study of serpentines with special regard to the occurrences in Hungary. PhD thesis, Library of Eotvos Lorand University, Budapest (in Hungarian).Google Scholar
Rucklidge, J.C. and Zussman, I (1965) Crystal structure of serpentine mineral lizardite Mg3Si2O5(OH)4 . Ada Crystallographica, 19, 381–389.CrossRefGoogle Scholar
Wicfc, FJ and Whitaker, EJW. (1977) Serpentine textures and serpentimzation. The Canadian Mineralogist, 15, 459–488.Google Scholar
Zega, TJ Garvle, LAJ Dodony, L Freidrich, H. Stroud, R.M. and Buseck, P.R. (2006) Polyhedral serpentine grains in CM ehondrites. Meteoritics and Planetary Science, 41, 681–690.CrossRefGoogle Scholar