Abstract
The electron structural analysis of a Madagascar sepiolite (Ampandrandava) was carried out by selected area electron diffraction obtained from monocristals. Fourier projections, derived from the experimental intensity of Okl, hOl and hkO reflections, show that the Mg2+ cations on the edges of the sheets are distributed between two sites. Correlatively the water molecules bound to these Mg2+ occupy two distinct positions. These principal structural differences with the Brauner and Preisinger model explain details of the i.r. spectra during the desorption of water or the adsorption of polar molecules. The differences between the two models can be considered as a consequence of treating the mineral in vacuum.
Similar content being viewed by others
References
Allpress, J. G. and Sanders, J. V. (1973) The direct observation of the structures of real crystals by lattice imaging. J. appl. Crystallogr. 6, 165–190.
Brauner, L. and Preisinger, A. (1956) Struktur und entstehung des sepioliths. Tschermaks Min. Petr. Mitt. 6, 120–140.
Brindley, G. W. (1959) X-Ray and electron diffraction data for sepiolite. Am. Miner. 44, 495–500.
Caillere, S. (1936) Thermal studies. Bull. Soc. Franc. Miner. 59, 353–374.
Cowley, J. M. and Moodie, A. F. (1962) The scattering of electrons by thin crystals. J. Phys. Soc. Japan. 17, 86–91.
Cowley, J. M. (1968) Acta geologica et geographica Universitatis Comenianae. No. 14. Slovenské Pedagogické Nakladatalastvo, Bratislava.
Martin-Vivaldi, J. L. and Cano-Ruiz, J. (1955) Contribution to the study of sepiolite: some consideration regarding the mineralogical formula. Clays and Clay Minerals, 4th Nat. Conf. U.S., N.R.C., 1956. 173–176.
Martin-Vivaldi, J. L. and Robertson, R. H. S. (1971) The Electron Optical Investigation of Clays (Edited by J. A. Gard), pp. 255–275. London Mineralogical Society.
Menter, J. W. (1956) Electron microscopy. Proc. Stockholm Conf. (Edited by Almquist and Wiksel) pp. 88–93.
Nagata Hiroshi, Susumu Shimoda and Toshio Sudo (1974) On dehydration of bound water of sepiolite. Clays and Clay Minerals 22, 285–293.
Nagy, B. and Bradley, W. F. (1955) The structural scheme of sepiolite. Am. Miner. 40, 885–892.
Pinsker, Z. G. (1968) Physical principles and certain results of the modern electron diffraction structure analysis. Acta geologica et geographica Universitatis Comenianae 14. Slovenské pedagogické nakladatalastvo, Bratislava.
Preisinger, A. (1963) Sepiolite and related compounds: its stability and application. Clays and Clay Minerals, Proc. Nat. Conf, Vol. 10, pp. 365–371. Pergamon Press, Oxford.
Prost, R. (1973) Spectre infra-rouge de l’eau présente dans l’attapulgite et dans la sépiolite. Bull. Gr. Franç. Argiles. 25, 53–63.
Rautureau, M. and Tchoubar, C. (1972) Etude morphologique de la sépiolite par microscopie électronique. J. Microsc. 14, 139–146.
Rautureau, M., Tchoubar, C. and Mering, J. (1972) Analyse structurale de la sépiolite par microdiffraction électronique. C. r. Acad. Sci. 274, 269–271.
Rautureau, M., Tchoubar, C. and Mering, J. (1972) Analyse structurale de la sépiolite à partir des données de la diffraction électronique. Int. Clay Conf. Madrid (Edited by J. M. Serratosa) pp. 115–121.
Serna, J. C. (1973) Naturaleza y propriedades de la superficie de la sepiolita. Thesis, University of Madrid.
Serna, J. C., Rautureau, M., Prost, R., Tchoubar, C. and Serratosa, J. M. (1974) Etude de la sépiolite à l’aide des données de la microscopie électronique, de l’analyse thermopondérale et de la spectroscopie infra-rouge. Bull. Groupe Franç. Argiles 26, 153–163.
Tchoubar, C., Rautureau, M., Clinard, C. and Ragot, J. P. (1973) Technique d’inclusion appliquée à l’étude des silicates lamellaires et fibreux. J. Microsc. 18, 147–154.
Zvyagin, B. B. (1967) Electron Diffraction Analysis of Clay Mineral Structures. Plenum Press, New York.
Author information
Authors and Affiliations
Additional information
This work is a part of the Doctoral Thesis of M. Michel Rautureau, 1974, University of Orleans, France.
Rights and permissions
About this article
Cite this article
Rautureau, M., Tchoubar, C. Structural Analysis of Sepiolite by Selected Area Electron Diffraction—Relations with Physico-Chemical Properties. Clays Clay Miner. 24, 43–49 (1976). https://doi.org/10.1346/CCMN.1976.0240105
Received:
Published:
Issue Date:
DOI: https://doi.org/10.1346/CCMN.1976.0240105