1989 Edition

Alkaline rocks—undersaturated

  • D. K. Bailey
Reference work entry

Nepheline syenite

Nepheline syenite is a pale-colored, coarse-grained rock composed essentially of alkali feldspar (ca. 70%) and nepheline (ca. 20%) with minor proportions of dark minerals such as sodic pyroxene, sodic hornblende, or biotite; its volcanic equivalent is phonolite. It was first described from Foya (hence the original name, foyaite ) in S Portugal by Blum (1861). Rosenbusch (1877) proposed the alternative name nepheline syenite. An historical review, and a systematic discussion of varieties and related rocks is given by Johannsen (1938). Use of the term foyaite has been confused by its adoption by some authors as a name for any nepheline syenite that shows fluidal textures.

Common accessory minerals are sphene (titanite), apatite, and iron ore, but nepheline syenites may carry a large range of uncommon minerals containing elements such as Ti, Zr, Nb, REE, U, Th ( Vlasov et al., 1966). The feldspathoid nepheline (NaAlSiO 4) reflects an inadequate silica content in the rock...
This is a preview of subscription content, log in to check access.


  1. Bailey, D. K. 1976, Applications of experiments to alkaline rocks, in D. K. Bailey and R. Macdonald, eds., The Evolution of the Crystalline Rocks. London: Academic Press, 416–469.Google Scholar
  2. Bailey, D. K., 1980, Volatile flux, geotherms, and the generation of the kimberlite-carbonitite-alkaline magma spectrum, Mineral. Mag. 43, 695–699.Google Scholar
  3. Bailey, D. K., 1982, Mantle metasomatism—continuing chemical change within the Earth, Nature 296, 525–530.Google Scholar
  4. Bailey, D. K., 1984, Kimberlite: “The Mantle Sample” formed by ultrametasomatism, in J. Kornprobst, ed., Kimberlites. I. Kimberlites and Related Rocks. Amsterdam: Elsevier, 323–333.Google Scholar
  5. Blum, R., 1861, Foyait, ein neues Gestein aus Sud-Portugal. Neues Jahrb. 426.Google Scholar
  6. Fitton, J. G. and B. G. J. Upton eds., 1987, Alkaline Igneous Rocks, Spec. Publ. Geol. Soc. London 30.Google Scholar
  7. Johannsen, A., 1938, A Descriptive Petrography of the Igneous Rocks, Vol. IV. University of Chicago Press.Google Scholar
  8. Le Bas, M. J., 1977, Carbonatite-Nephelinite Volcanism: an African Case History. London: Wiley.Google Scholar
  9. Lehijarvi, M., 1960, The alkaline district of Iivaara, Kuusamo, Finland, Bull. Comm. Geol. Finl. 185.Google Scholar
  10. Le Maitre, R. W., 1976, The chemical variability of some common igneous rocks, J. Petrol. 17, 589–598.Google Scholar
  11. Nockolds, S. R., 1954, Average chemical compositions of some igneous rocks, Bull. Geol. Soc. Am. 65, 1007–1032.Google Scholar
  12. Rosenbusch, H., 1877, Mikroskopische Physiographie II. Stuttgart: Schweizerbart.Google Scholar
  13. Sørensen, H. ed., 1974, The Alkaline Rocks. New York: Wiley.Google Scholar
  14. Streckeisen, A. L., 1976, To each plutonic rock its proper name, Earth Sci. Rev. 12, 1–34.Google Scholar
  15. Vlasov, K. A., M. V. Kuz-Menko, and E. M. Es'kova, 1966, The Lovozero Alkali Massif. Edinburgh: Oliver & Boyd.Google Scholar

Copyright information

© Van Nostrand Reinhold 1989

Authors and Affiliations

  • D. K. Bailey

There are no affiliations available