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Gahnite compositions compared

Published online by Cambridge University Press:  05 July 2018

Richard A. Batchelor  and
Judith A. Kinnaird
Richard A. Batchelor
Affiliation:
Department of Geology, University of St Andrews, St Andrews, Fife, Scotland
Judith A. Kinnaird
Affiliation:
Department of Geology, University of St Andrews, St Andrews, Fife, Scotland
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Abstract

Blue-coloured gem-quality spinel from Nigeria was analysed by wet chemical methods (using atomic absorption spectrophotometry) and investigated by X-ray diffraction. The results showed it to be gahnite (unit cell dimension a=8.091±0.003 Å) containing 36.7% ZnO, 3.58% FeO, and 0.12% MgO. The spinel has an RI of 1.79 and density between 4.4 and 4.59. Broadening of the n[111] XRD reflections indicates a measure of compositional heterogeneity. The gahnite analyses were compared with compositions of zinc spinels from other parts of the world. The analyses cluster into two distinct groups, Mg-rich spinels of metamorphic origin and Mg-poor spinels (including the Nigerian gahnite) with igneous affinities. Diadochy seems to operate within the zinc spinel structure between (Zn + Mn) and (Fe + Mg).

Type
Research Article
Information
Mineralogical Magazine , Volume 48 , Issue 348 , September 1984 , pp. 425 - 429
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1984

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References

Alvarez-Perez, A., Campa-Vineta, J. A., and Montoriol-Pous, J. (1974) Acta Geol. Hispanica. 9, 111-13.Google Scholar
Anderson, D. W., and Payne, C. J. (1937) Mineral. Mag. 24, 547-54.Google Scholar
Boar, P. L., and Ingram, L. K. (1970) Analyst. 95, 124-30.CrossRefGoogle Scholar
Brush, G. J. (1871) Am. J. Sci. (3rd ser.), 1, 28-9.Google Scholar
Deer, W. A., Howie, R. A., and Zussman, J. (1962) Rockforming minerals, 5. Longmans, London.Google Scholar
Eskola, P. (1914) Geol. Foren. Forhandl. 36, 25–30.CrossRefGoogle Scholar
Frost, B. R. (1973) Am. Mineral. 58, 831-4.Google Scholar
Gandhi, S. M. (1971) Mineral. Mag. 38, 528-9.CrossRefGoogle Scholar
Ingamells, C. O. (1970) Anal. Chim. Acta. 52, 323-34.CrossRefGoogle Scholar
Jackson, B. (1982) J. Gemmology. 18, 265-76.CrossRefGoogle Scholar
Jacobson, R. R. E., and Webb, J. S. (1946) Bull. Geol. Surv. Nigeria, No. 17.Google Scholar
Kloosterman, J. B. (1969) Proc. 2nd. Tech. Conf. Tin, Bangkok. 1, 195-221. Int. Tin Council, London, 1970.Google Scholar
Kloosterman, J. B. (1970) Proc. VIII Guyanas Geol. Conf. Georgetown, 18 pp.Google Scholar
Lisitsyn, A. E., and Yurkina, K. B. (1974) Zap. Vses. Mineral. Obshch. 103, 641-3.Google Scholar
Palache, C., Berman, H., and Frondel, C. (1944) Dana's System of Mineralogy, 7th edn. 1. John Wiley.Google Scholar
Pearce, T. H. (1968) Contrib. Mineral. Petrol. 19, 142-57.CrossRefGoogle Scholar
Pehrman, B. (1948) Bull. Geol. Inst. Uppsala 32, 329-36.Google Scholar
Shannon, E. V. (1923) Am. Mineral. 8, 147-8.Google Scholar
Simpson, E. S. (1930) J.R. Soc. West. Australia 16, 30-2.Google Scholar
Simpson, E. S. (1931) Ibid. 17, 137.Google Scholar
Simpson, E. S. (1937) Ibid. 23, 30-1.Google Scholar
Stoddard, E. F. (1979) Am. Mineral. 64, 736-41.Google Scholar
Taylor, S. R. (1965) Phys. Chem. Earth. 6, 178.CrossRefGoogle Scholar