Abstract
The electron back-scattered diffraction (EBSD) technique has been applied to fine-grained kaolin minerals to determine the polytypes (kaolinite, dickite and nacrite) of individual grains and their crystallographic orientations in a scanning electron microscope (SEM). Because kaolin minerals are prone to radiation damage by the intense electron beam necessary to obtain EBSD patterns, the beam has to be rastered across the specimens during pattern acquisition. Kaolinite-dickite and nacrite are easily distinguished by their trigonal or hexagonal symmetry about the [001]* direction, respectively, of the Kikuchi bands with k = 3n. Dickite can be differentiated from kaolinite by mirror symmetry parallel to the ac plane, and by the characteristic contrast of HOLZ rings.
As EBSD analysis is performed using a SEM, morphological characters can be correlated with polytypes. Dickite fragments could be discerned as oriented overgrowths on nacrite plates. Dickite was observed to always adopt euhedral shapes in a diagenetic mixture of kaolinite and dickite. Lath-shaped dickite is elongated along the a axis direction. Rhombohedral dickite consists of crystals with {1̄11} indexed to the side facets.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Baba-Kishi, K.Z. (1998) Measurement of crystal parameters on backscatter Kikuchi diffraction patterns. Scanning, 20, 117–127.
Bailey, S.W. (1963) Polymorphism of the kaolin minerals. American Mineralogist, 48, 1196–1209.
Bailey, S.W. (1988) Polytypism of 1:1 layer silicates. Pp. 927 in: Hydrous Phyllosilicates (Exclusive of Micas) (S.W. Bailey, editor). Reviews in Mineralogy, 19. Mineralogical Society of America, Washington, D.C.
Beaufort, D., Cassangnabere, A., Petit, S., Lanson, B., Berger, G., Lacharpagne, J.C. and Johansen, H. (1998) Kaolinite-to-dickite reaction in sandstone reservoirs. Clay Minerals, 33, 297–316.
Bish, D.L. and Johnston, C.T. (1993) Rietveld refinement and Fourier-transform infrared spectroscopic study of the dickite structure at low temperature. Clays and Clay Minerals, 41, 297–304.
Brindley, G.W. and Robinson, K. (1946) Randomness in the structures of kaolinitic clay minerals. Transactions of the Faraday Society, 42B, 198–205.
Buatier, M.D., Potdevin, J.-L., Lopez, M. and Petit, S. (1996) Occurrence of nacrite in the Lodéve Permian basin (France). European Journal of Mineralogy, 8, 847–852.
Dingley, D.J. (1984) Diffraction from sub-micron areas using electron backscattering in a scanning electron microscope. Scanning Electron Microscopy, 11, 569–575.
Dingley, D.J. and Rändle, V. (1992) Microtexture determination by electron back-scatter diffraction. Journal of Materials Science, 27, 4545–4566.
Ehrenberg, S.N., Aagaard, P., Wilson, M.J., Fraser, A.R. and Duthie, D.M.L. (1993) Depth-dependent transformation of kaolinite to dickite in sandstones of the Norwegian Continental Shelf. Clay Minerals, 28, 325–352.
Giese, R.F. (1988) Kaolin minerals: structures and stabilities. Pp. 2966 in: Hydrous Phyllosilicates (Exclusive of Micas) (S.W. Bailey, editor). Reviews in Mineralogy, 19. Mineralogical Society of America, Washington, D.C.
Güven, N. (1974) Lath-shaped units in fine-grained micas and smectite. Clays and Clay Minerals, 22, 385–390.
Harland, C.J., Akhter, P. and Venables, J.A. (1981) Accurate microcrystallography at high spatial resolution using electron backscattering patterns in a field-emission gun scanning electron microscope. Journal of Physics, E14, 175–182.
Humphreys, F.J. and Brough, I. (1999) High resolution electron backscatter diffraction with a field emission gun scanning electron microscope. Journal of Microscopy — Oxford, 195, 69.
Kogure, T. (2002a) Identification of polytypic groups in hydrous phyllosilicates using Electron Back-Scattering Patterns (EBSPs). American Mineralogist, 87, 1678–1685.
Kogure, T. (2002b) Investigation of micas using advanced TEM. Pp. 281312 in: Micas: Crystal Chemistry & Metamorphic Petrology (A. Mottana, F.P. Sassi, J.B. Thompson, Jr. and S. Guggenheim, editors). Reviews in Mineralogy and Geochemistry, 46. Mineralogical Society of America and the Geochemical Society, Washington, D.C.
Kogure, T. (2003) A program to assist Kikuchi pattern analysis. Journal of the Crystallographic Society of Japan, 45, 391–395 (in Japanese with English abstract; the program is available from https://doi.org/www.gbs.eps.s.u-to-kyo.ac.jp/kogure/edana).
Kogure, T. and Bunno, M. (2004) Investigation of polytype occurrence in lepidolite by using Electron Back-Scattering Diffraction (EBSD). American Mineralogist, 89, 1680–1684.
Kogure, T. and Inoue, A. (2005) Determination of defect structures in kaolin minerals by High-Resolution Transmission Electron Microscopy (HRTEM). American Mineralogist, 90, 85–89.
Kogure, T., Hybler, J. and Yoshida, H. (2002) Coexistence of two polytypic groups in cronstedtite from Lostwithiel, England. Clays and Clay Minerals, 50, 504–513.
Lanson, B., Beaufort, D., Berger, G., Bauer, A., Cassagnabère, A. and Meunier, A. (2002) Authigenic kaolin and illitic minerals during burial diagenesis of sandstones: a review. Clay Minerals, 37, 1–22.
Michael, J.R. and Eades, J.A. (2000) Use of reciprocal lattice layer spacing in electron backscatter diffraction pattern analysis. Ultramicroscopy, 81, 67–81.
Murray, H.H. (1988) Kaolin minerals: Their genesis and occurrence. Pp. 67–90 in: Hydrous Phyllosilicates (Exclusive of Micas) (S.W. Bailey, editor). Reviews in Mineralogy, 19. Mineralogical Society of America, Washington, D.C.
Neder, R.B., Burghammer, M., Grasl, T., Schulz, H., Bram, A. and Fiedler, S. (1999) Refinement of the kaolinite structure from single-crystal synchrotron data. Clays and Clay Minerals, 47, 487–494.
Prior, D.J., Boyle, A.P., Brenker, F., Cheadle, M.C., Day, A., Lopez, G., Peruzzo, L., Potts, G.J., Reddy, S., Spiess, R., Timms, N.E., Trimby, P., Wheeler, J. and Zetterström, L. (1999) The application of electron backscatter diffraction and orientation contrast imaging in the SEM to texture problem in rocks. American Mineralogist, 84, 1741–1759.
Robertson, I.D.M. and Eggleton, R.A. (1991) Weathering of granitic muscovite to kaolinite and halloysite and of plagioclase-derived kaolinite to halloysite. Clays and Clay Minerals, 36, 113–126.
Ruiz Cruz, M.D. (1996) Dickite, nacrite and possible dickite/nacrite mixed-layers from the Betic Cordilleras (Spain). Clays and Clay Minerals, 44, 357–369.
Schmidt, E.R. and Heckroodt, R.O. (1959) A dickite with an elongated crystal habit and its dehydroxylation. Mineralogical Magazine, 32, 314–323.
Seward, G.G.E., Celotto, S., Prior, D.J., Wheeler, J. and Pond, R.C. (2004) In situ SEM-EBSD observations of the hep to bec phase transformation in commercially pure titanium. Acta Materialia, 52, 821–832.
Shutov, V.D., Aleksandova, A.V. and Losievskaya, S.A. (1970) Genetic interpretation of the polymorphism of the kaolinite group in sedimentary rocks. Sedimental, 15, 69–82.
Venables, J.A. and Harland, C.J. (1973) Electron back-scattering patterns — A new technique for obtaining crystallographic information in the scanning electron microscope. Philosophical Magazine, 27, 1193–1200.
Zheng, H. and Bailey, S.W. (1994) Refinement of the nacrite structure. Clays and Clay Minerals, 42, 46–52.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Kogure, T., Inoue, A. & Beaufort, D. Polytype and Morphology Analyses of Kaolin Minerals By Electron Back-Scattered Diffraction. Clays Clay Miner. 53, 201–210 (2005). https://doi.org/10.1346/CCMN.2005.0530301
Received:
Revised:
Published:
Issue Date:
DOI: https://doi.org/10.1346/CCMN.2005.0530301