Crystal Chemistry and Stability of a High-Pressure Hydrous 10Å Layer Silicate in the System MgO-SiO2-H2O

  • J. F. Bauer
  • C. B. Sclar


Previous studies in the system MgO-SiO2-H2O at high pressures [1,2,3,4] has resulted in the discovery of a unique, quenchable, hydrous phyllosilicate phase with the deduced chemical formula [(H3O)2Mg5Si8O20(OH)4]. This phase was synthesized by reaction of brucite [Mg(OH)2] — silicic acid mixtures in the pressure and temperature range 3.2 < P < 9.5 GPa and 375 < T < 525°C, respectively. Preliminary crystallographic analysis of this phase [1] indicated that its structure was that of a mica with a 10-Å basal spacing; in this model structure, the presence of discrete H3O+ ions in the 12-coordinated interlayer sites was invokéd. The apparent alkali-bearing isostructural equivalents of this phase, namely, K2Mg5Si8O20(OH)4 and Na2Mg5Si8O20(OH)4, were independently synthesized at pressures of 0.1 GPa and 0.1–0.5 GPa by Seifert and Schreyer [5] and Franz and Althaus [6], respectively. The potassium end member was later found to be part of an extensive solid-solution series which included the aluminous mica phlogopite [K2Mg6Al2Si6O20(OH)4] [7] and the solid-solution series [K2Mg5Si8O20(OH)4 – K2Fe5 +2Si8O20(OH)4] has also been synthesized [8]. The high-pressure 10-Å phase in the system MgO-SiO2-H2O, therefore, appeared to be an oxonium-bearing non-aluminous member of the phlogopite series of micas. Recent high-pressure experimentation [9] using brucite-silica gel mixtures representing a wide range of bulk compositions indicates that the composition of the 10-Å phase is represented best by the stoichiometric ratio 3MgO:4SiO2:2H2O, which appears to be incompatible with a simple mica model. It was concluded [9] that the thermal stability of the 10-Å phase was much greater than initially proposed [1,2,4].


Bulk Composition Crystal Chemistry Discrete Absorption Concomitant Weight Loss Graphite Resistance Furnace 
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  1. 1.
    C. B. Sclar, L. C. Carrison and C. M. Schwartz, Trans. Amer. Geophys. Union 46, 184 (1965).Google Scholar
  2. 2.
    C. B. Sclar, L. C. Carrison and C. M. Schwartz, paper 2-B-65F Extended abstracts, Basic Sci. Div., Amer. Cer. Soc. Fall Mtg. (1965).Google Scholar
  3. 3.
    C. B. Sclar, and L. C. Carrison, Science 153, 1285 (1966).CrossRefGoogle Scholar
  4. C. B. Sciar, in Proc. USARO-Durham Conference on New Materials from High-Pressure High-Temperature Processes (1967), p. 135.Google Scholar
  5. 5.
    F. Seifert and W. Schreyer, Amer. Mineral. 50, 1114 (1965).Google Scholar
  6. 6.
    G. Franz and E. Althaus, Contr. Mineral. and Petrol. 46, 227 (1974).CrossRefGoogle Scholar
  7. 7.
    F. Seifert and W. Schreyer, Contr. Mineral. and Petrol. 30, 196 (1971).CrossRefGoogle Scholar
  8. 8.
    T. Kwak, Neues Jahrb. fir Mineral. Monats. 1971 326 (1971).Google Scholar
  9. 9.
    K. Yamamoto and S. Akimoto, Amer. J. Sci. 277 288 (1977).Google Scholar
  10. 10.
    C. B. Sciar, L. C. Carrison and C. M. Schwartz, in High Pressure Measurement A. A. Giardini and E. C. Lloyd, eds., Butterworths, London (1963).Google Scholar
  11. 11.
    R. M. Hazen and D. W. Wones, Amer. Mineral. 57, 103 (1972).Google Scholar
  12. 12.
    J. V. Smith and H. S. Yoder, Mineral. Mag. 31, 209 (1956).CrossRefGoogle Scholar
  13. 13.
    D. E. Appleman and H. T. Evans, Jr., NTIS Publ. Pb 216–188 (1973).Google Scholar
  14. 14.
    R.W.T. Wilkins and J. Ito, Amer. Mineral. 52, 1649 (1967).Google Scholar
  15. 15.
    J. D. Russell, V. C. Farmer and B. Velde, Mineral. Mag. 37, 869 (1970).CrossRefGoogle Scholar
  16. 16.
    J. D. Russell, in The Infrared Spectra of Minerals V. C. Farmer, ed., Mineral Soc., London (1974).Google Scholar
  17. 17.
    C. Ferriso and P. Hornig, J. Chem. Phys. 23, 1464 (1955).CrossRefGoogle Scholar
  18. 18.
    M. G. Fournier, G. Mascherpa, D. Rousselet and J. Potier, C. R. Acad. Sci. Ser. C. 269, 279 (1969).Google Scholar
  19. 19.
    R.W.T. Wilkins, A. Mateen and G. W. West, Amer. Mineral. 59, 811 (1974).Google Scholar
  20. 20.
    J. L. White and A. F. Burns, Science 141, 800 (1963).CrossRefGoogle Scholar
  21. 21.
    G. V. Yukhnevich, Russ. Chem. Rev. 32, 619 (1963).Google Scholar
  22. 22.
    J. J. Fawcett and H. S. Yoder, Amer. Mineral. 51, 353 (1966).Google Scholar
  23. 23.
    P. J. Modreski and A. L. Boettcher, Amer. J. Sci. 273, 385 (1973).CrossRefGoogle Scholar
  24. 24.
    S. Kitahara, S. Takenouchi and G. C. Kennedy, Amer. J. Sci. 264, 223 (1966).CrossRefGoogle Scholar
  25. 25.
    C. B. Sclar and S. P. Morzenti, Geol. Soc. Amer., Abstracts with Programs 3, 698 (1971).Google Scholar
  26. 26.
    C. B. Sclar and J. F. Bauer, in Intern. Conf. Geotherm. Geobarom. Extended Abstracts, Pennsylvania State University (1975).Google Scholar

Copyright information

© Springer Science+Business Media New York 1979

Authors and Affiliations

  • J. F. Bauer
    • 1
  • C. B. Sclar
    • 1
  1. 1.Lehigh UniversityBethlehemUSA

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