Skip to main content

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

  • Letter
  • Published:

A silica-rich sodium pyroxene phase with six-coordinated silicon

Abstract

Phase transitions in minerals and melts that involve a change in the coordination of silicon from fourfold to sixfold are generally accompanied by large changes in material properties such as density, bulk modulus and elastic moduli. When such transformations occur within the Earth, these large changes in material properties can result in seismic discontinuities. The presence of six-coordinated silicon in minerals such as majorite garnet at upper-mantle pressures is therefore of crucial importance to an understanding of the properties of this region of the Earth. The silicate pyroxenes are also believed to comprise a significant portion of the upper mantle1, and to provide a host for large cations such as sodium and calcium. It has long been assumed that silicon is restricted to the tetrahedral sites within the pyroxene structure. Here, however, we report the high-pressure synthesis and characterization of single crystals of a pyroxene of nominal stoichiometry Na(Mg0.5Si0.5)Si2O6, which is the first pyroxene known to contain both tetrahedrally and octahedrally coordinated silicon.

This is a preview of subscription content, access via your institution

Access options

Similar content being viewed by others

References

  1. Takahashi, E. & Ito, E. in High-Pressure Research in Mineral Physics (eds Manghnani, M. H. & Syono, Y.) (American Geophysical Union, Washington DC, 1987).

    Google Scholar 

  2. Gasparik, T. Eos 69, 500 (1988).

    Google Scholar 

  3. Prewitt, C. T. & Burnham, C. W. Am. Miner. 51, 956–975 (1966).

    CAS  Google Scholar 

  4. Finger, L. W. & Prince, E. Natn. Bur. Stand. Tech. Note 854 (1974).

  5. Curtis, L. et al. Can. Mineralogist 13, 62–67 (1975).

    Google Scholar 

  6. International Tables for X-ray Crystallography Vol. 4 (Kynoch, Birmingham, 1974).

  7. Smyth, J. R. & Bish, D. L. Crystal Structures and Cation Sites of the Rock-Forming Minerals (Allen and Unwin, Boston, 1988).

    Google Scholar 

  8. Sinclair, W. & Ringwood, E. A. Nature 272, 714 (1978).

    Article  ADS  CAS  Google Scholar 

  9. Swanson, D. K. & Prewitt, C. T. Am. Miner. 68, 581–585 (1983).

    CAS  Google Scholar 

  10. Horiuchi, H., Hirano, M., Ito, E. & Matsui, Y. Am. Miner. 67, 788–793 (1982).

    CAS  Google Scholar 

  11. Horiuchi, H., Ito, E. & Weidner, D. J. Am. Miner. 72, 357–360 (1987).

    CAS  Google Scholar 

  12. Gasparik, T. Geochim. cosmochim. Acta 48, 2537–2545 (1984).

    Article  ADS  CAS  Google Scholar 

  13. Robinson, K., Gibbs, G. V. & Ribbe, P. H. Science 172, 567–570 (1971).

    Article  ADS  CAS  Google Scholar 

  14. Fisher, R. X. J. appl. Crystallogr. 18, 258–262 (1984).

    Article  Google Scholar 

Download references

Author information

Authors and Affiliations

Authors

Rights and permissions

Reprints and permissions

About this article

Cite this article

Angel, R., Gasparik, T., Ross, N. et al. A silica-rich sodium pyroxene phase with six-coordinated silicon. Nature 335, 156–158 (1988). https://doi.org/10.1038/335156a0

Download citation

  • Received:

  • Accepted:

  • Issue Date:

  • DOI: https://doi.org/10.1038/335156a0

This article is cited by

Comments

By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.

Search

Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing