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An X-ray powder method for the estimation of (K, Ba) feldspars

Published online by Cambridge University Press:  14 March 2018

P. Gay*
Affiliation:
Department of Mineralogy and Petrology, Cambridge

Summary

Examination of previous physical methods of estimating the barium-content of these feldspars showed that they are generally unsatisfactory. A new variation diagram is constructed correlating BaO content and values of d132 determined from diffractometer records. It is estimated that the BaO content of these feldspars can normally be determined to about 2–3% by using this diagram.

Some of the problems of the mineralogy of the series are reviewed in the light of the experimental results, in particular the effect of polymorphic changes on the variation diagram. Some experimental evidence of the effect of different structural states upon the value of d132 is obtained, and the limitations imposed upon the method by the existence of such states are discussed.

Type
Research Article
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1965

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References

Gay, (P.), 1956. Acta Cryst., vol. 9, p. 474.CrossRefGoogle Scholar
Newham, (R.E.) and MeGaw, (H.D.), 1960. Ibid., vol. 13, p. 303.Google Scholar
Segnit, (E.R.), 1946. Min. Mag., vol. 27, p. 166.Google Scholar
Vermaas, (F. H. S.), 1953. Amer. Min., vol. 38, p. 845.Google Scholar
Yosimura, (T.), 1939. Journ. Fac. Sci. Univ. Hokkaido, Set. 4, vol. 4, p. 31.Google Scholar