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On the Chemical Classification of the Mica Group. II. The Basic Micas

Published online by Cambridge University Press:  14 March 2018

A. F. Hallimond
A. F. Hallimond*
Affiliation:
Museum of Practical Geology, London1
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Extract

In the first part of this paper it was shown that the acid section of the mica group could be divided into two main series, the potash micas and the lithia micas. The molecular ratio of potash to silica was 1 : 6 and the micas were therefore represented as salts of an acid characterized by this value. The present section contains the result of a similar investigation of the basic micas, especially biotite and phlogopite; here again it will be seen that the grouping K2O. 6SiO2 is present throughout. For comparison of the molecular composition, the analyses of the basic micas have been recalculated in molecular ratios, (Si,Ti)O2 being made equal to 600 according to the method already used for the acid micas.

Type
Research Article
Information
Mineralogical magazine and journal of the Mineralogical Society , Volume 21 , Issue 113 , June 1926 , pp. 25 - 33
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1926

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References

page 25 note 2 Hallimond, A. F., Min. Mag., 1925, vol. 20, pp. 305–318 Google Scholar.

page 26 note 1 Dana's ‘System of Mineralogy', 6th ed., 1892, pp. 680, 631, 633.

page 26 note 2 Boeke, H. E., Neues Jahrb. Min., 1916, vol. 1, pp. 89–95 Google Scholar. [Min. Abstr, vol. 1, p. 245.]

page 26 note 3 A. N. Winchell, Amer. Journ. Sci., 1925, ser. 5, vol. 9, pp. 309-327, 415-450, diagram p. 321. [Min. Abstr., vol. 3, p. 12.]

page 26 note 4 Figs. 1-2 were given in Part I of this paper.