Polyhedron distortions in tourmaline
- Author(s)
- Andreas Ertl, John M. Hughes, Franz Pertlik, Jr Franklin F. Foit, Stephen E. Wright, Franz Brandstätter, Bernd Marler
- Abstract
Distortion parameters [?, s2, DI(Y-O), DI(O-Y-O), DI(O-O)] have been calculated for cation polyhedra in tourmalines of different chemical compositions. Tourmalines with greater amounts of small, highly charged ions in the YO6 octahedron display greater bond-length distortion in Y. The size and charge of the occupants at the Y site have been included in an empirically determined formula intended to evaluate the bond-length distortion of the YO6 octahedron. This equation demonstrates that the bond-length distortion in the YO6 octahedron is a function of the size and charge of the Y-site occupants, and is predictable from those occupants (r = 0.972 for observed versus calculated distortion). The distortion of the Z octahedron in a tourmaline is largely a function of the of that tourmaline [r = -0.985 for all tourmalines where 03 is occupied by 3 (OH) apfu], although the occupant of the 03 site also affects that distortion. The bond-length distortion of the TO4 tetrahedron is small, but examination of the angle distortion of the tetrahedron demonstrates a strong covariance with the charge at the X site (r = 0.892). Finally, distortions in the XO9 polyhedron were found to correlate with the charge of the occupants at the Y site and the fluorine content (r = 0.881).
- Organisation(s)
- Department of Mineralogy and Crystallography
- External organisation(s)
- Miami University, Washington State University, University of Miami, Geologisk Museum, Ruhr-Universität Bochum (RUB)
- Journal
- The Canadian Mineralogist
- Volume
- 40
- Pages
- 153-162
- No. of pages
- 10
- ISSN
- 0008-4476
- Publication date
- 2002
- Peer reviewed
- Yes
- Austrian Fields of Science 2012
- 1051 Geology, Mineralogy
- Portal url
- https://ucrisportal.univie.ac.at/en/publications/ae01bcbe-3f95-4bb6-99d3-d2109485478d