Advertisement

Physics and Chemistry of Minerals

, Volume 25, Issue 2, pp 142–151 | Cite as

Raman spectra of silicate garnets

  • B. A. Kolesov
  • C. A. Geiger
ORIGINAL PAPER

Abstract 

The single-crystal polarized Raman spectra of four natural silicate garnets with compositions close to end-members almandine, grossular, andradite, and uvarovite, and two synthetic end-members spessartine and pyrope, were measured, along with the powder spectra of synthetic pyrope-grossular and almandine-spessartine solid solutions. Mode assignments were made based on a comparison of the different end-member garnet spectra and, in the case of pyrope, based on measurements made on additional crystals synthesized with 26Mg. A general order of mode frequencies, i.e. R(SiO4)>T(metal cation)>T(SiO4), is observed, which should also hold for most orthosilicates. The main factors controlling the changes in mode frequencies as a function of composition are intracrystalline pressure (i.e. oxygen-oxygen repulsion) for the internal SiO4-vibrational modes and kinematic coupling of vibrations for the external modes. Low frequency vibrations of the X-site cations reflect their weak bonding and dynamic disorder in the large dodecahedral site, especially in the case of pyrope. Two mode behavior is observed for X-site cation vibrations along the pyrope-grossular binary, but not along the almandine-spessartine join.

Keywords

Mode Frequency Mode Behavior Orthosilicate External Mode Almandine 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

Copyright information

© Springer-Verlag Berlin Heidelberg 1998

Authors and Affiliations

  • B. A. Kolesov
    • 1
  • C. A. Geiger
    • 2
  1. 1.Institute of Inorganic Chemistry, Lavrentiev prosp. 3, Novosibirsk 630090, RussiaRU
  2. 2.Mineralogisch-Petrographisches Institut, Universität Kiel, Olshausenstr. 40, D-24098 Kiel, Germany Fax: +49 04 31 8 80-44 57; e-mail: NMP4b@rz.uni-kiel.deDE

Personalised recommendations