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Optical dispersion of three intermediate plagioclases

Published online by Cambridge University Press:  14 March 2018

Seitarô Tsuboi
Seitarô Tsuboi*
Affiliation:
Of the Geological Institute, Imperial University of Tokyo, Japan
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Extract

The optical dispersion phenomena of felspars at the alkalic and calic ends of the plagioclase series have been investigated by C. Viola and S. Kôzu, but for those of intermediate composition the data have been lacking. In view of the usefulness of the dispersion data of felspars for their determination in cleavage-flakes by the method to be described in the next paper, the present writer has made a study of the dispersion of certain intermediate plagioelases.

Type
Research Article
Information
Mineralogical magazine and journal of the Mineralogical Society , Volume 20 , Issue 102 , September 1923 , pp. 93 - 107
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1923

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References

Page 93 note 1 Viola, C., Zeits. Kryst. Min., 1899, vol. 30, p. 437 Google Scholar ; 1900, vol. 82, p. 805.

Page 93 note 2 Kôzu, S., Sci. Rep. Tôhoku Imp. Univ. Sendai, Japan, 1914, ser. 2, vol. 2, p. 7 Google Scholar ; Min. Mag., 1915, vol. 17, p. 189.

Page 94 note 1 Offret, A., Bull. Soc. Franç, Min., 1890, vol. 13, p. 648 Google Scholar.

Page 94 note 2 Viola, C., Zeits. Kryst. Min., 1900, vol. 82, p. 383 Google Scholar.

Page 94 note 3 Tertsch, H., Tscherm. Min. Petr. Mitt., 1903, vol. 22, p. 159 Google Scholar.

Page 94 note 4 Kòzu, S., Min. Mag.., 1916, vol. 17, p. 255 Google Scholar.

Page 95 note 1 In some of the following figures certain points have been displaced a little from their true positions in order to make the figures clearer.

Page 97 note 1 ϕ and λ are respectively the latitude and the longitude of the optic axis in the spherical projection, taking the great circle parallel to b (010) as the equator, and the meridian of the c-axis as the initial meridian (cf. fig. 2). In fig. 2, ϕ is positive when measured to the right (i.e. in the first and fourth quadrants); and λ is positive when measured upward (i. e. in the first and second quadrants).

Page 97 note 2 ∠β, the angle between the crystallographic axes c : a, for Ab 76 An 24 is 116° 23.6' according to E. Schmidt, Die Winkel der kristallographischen Achsen der Plagioklase. Chemie dcr Erde, Jena, 1915, vol. 1, p. 351; Inaug.-Diss., Heidelberg, 1916. [Min. Abstr., vol. 1, p. 890.]

Page 98 note 1 Throughout this paper, ρ, θ, ϕ, and λ for B are denoted as ρ′, θ′, ϕ′, and λ′ respectively, to avoid confusion with those for A.

Page 99 note 1 This relation holds good for any positions of A and B, taking signs of ϕ, λ, ϕ′, and λ′ into consideration.

Page 100 note 1 Wads, T., Minerals of Japan, 1904, p. 135 Google Scholar ; revised edition (in Japanese), 1916, p. 184.

Page 100 note 2 Becke, F. and Goldschlag, M., Sitzungsber. Akad. Wiss. Wien, Math.-naturw. Kl., 1918, vol. 127, Abt. I, p. 502 Google Scholar ; Becke, F., Tscherm. Min. Petr. Mitt., 1921, vol. 35, p. 31 Google Scholar. [Min. Abstr., vol. 1, p. 391 ; vol. 2, p. 61.]

Page 101 note 1 Hutchinson, A. and Campbell Smith, W., Min. Mag., 1912, vol. 16, p. 264.CrossRefGoogle Scholar

Page 102 note 1 The analyses are given in the above cited paper (p. 270) by A. Hutchinson and W. Campbell Smith. The mean of the three analyses: