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Rotated and extended model structures in amphiboles and pyroxenes

Published online by Cambridge University Press:  05 July 2018

A. D. Law  and
E. J. W. Whittaker
A. D. Law
Affiliation:
Department of Geology and Mineralogy, Parks Road, Oxford OXI 3PR
E. J. W. Whittaker
Affiliation:
Department of Geology and Mineralogy, Parks Road, Oxford OXI 3PR
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Summary

The model for the amphibole and pyroxene structures based on close-packed oxygen layers introduced by Thompson is investigated systematically. It is shown that different features of it can best be understood in terms of three different symbolisms: the O and S rotations of tetrahedra; the A,B, C stacking notation for close-packed layers; and the c, h notation for the relationship of close-packed layers to their neighbours. The possible stacking arrangements and their space-groups are derived systematically. Relationships between the close-packed, fully rotated, model and the extended chain model are discussed, and some important drawbacks in the former model are pointed out, especially in connection with real amphibole structures.

Type
Research Article
Information
Mineralogical Magazine , Volume 43 , Issue 329 , March 1980 , pp. 565 - 574
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1980

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Footnotes

*

Present address: Queen Mary College, London.

References

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