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The optical orientation of labradorite from County Down (Ireland) determined by the Fedorov Method

Published online by Cambridge University Press:  14 March 2018

W. Campbell Smith
W. Campbell Smith*
Affiliation:
Mineral Department of the British Museum (Natural History)
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Extract

Labradorite of exceptional purity, occurring as phenocrysts in two basaltic dikes just below the lighthouse at St. John's Point, Ardglass, County Down, Northern Ireland, was described by Professor A. Hutchinson and myself in 1912. The refractive indices for sodium-light were determined on an Abbé-Pulfrich total-reflectometer. Carefully selected material was analysed by Mr. G. G. Knighton and by Mr. M. C. Burkitt, and the specific gravity of the material analysed was determined.

Type
Research Article
Information
Mineralogical magazine and journal of the Mineralogical Society , Volume 21 , Issue 122 , September 1928 , pp. 543 - 551
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1928

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References

page 543 note 1 Hutchinson, A. and Campbell Smith, W., On sericite from North Wales and oh penninite and labradorite from Ireland. Min. Mag., 1912, vol. 16, pp. 267-271 Google Scholar.

page 543 note 2 Tsuboi, S., Optical dispersion of three intermediate plagioelases. Min. Mag., 1923, vol. 20, pp. 101–107 Google Scholar.

page 544 note 1 W. W. Nikitin, La methode universelle de Fedoroff. French translation by L. Duparc and V. de Dervies, Genève, Paris, and Liege, 1914, 516 pp. and atlas.

page 544 note 2 L. Dupare and M. Keinhard, La détermination des plagioclases dans les coupes minces. Mém. Soc. Phys. Hist. Nat. Genève, 1924, vol. 40, pp. 1-149, 59 text-figs., 18 pis. [Min. Abstr., vol. 3, p. 34.]

page 544 note 3 M. Berek, Mikroskopische Mineralbestimmung mit Hilfe der Universaldrehtisehmethoden. Berlin, 1924, 168 pp., 55 text-figs.. 7 pis. [Min. Abstr., vol. 2, p. 365.]

page 544 note 4 ‘Bluish glaucous’, see E. Ridgway, Color standards and nomenclature. Washington, 1912, pL 42.

page 544 note 5 Loc. cit., p. 38.

page 545 note 1 ‘Complex’: term used by Fedorov for a combination of a normal hemitrope with a parallel hemitrope having the same plane of association.

page 549 note 1 A stereographic net with six-inch radius and graduated to single degrees is printed nt the University Press, Cambridge, for the Mineralogical Department of the University. This is reduced by permission of the Hydrograpliic Department of the United States Navy from the net prepared in 1888 by the late Admiral C. D. Sigsbee.

page 549 note 2 M. Gysin, Note sur l'étude de qnelqucs caracteres des plagioelases. Compte Eendu Soc. Phys. Hist Nat. Genève, 1922, vol. 39, p. 73.

page 550 note 1 A. Borloz, Contribution à l'étude des plagioclases des roches d'epanchement. Univ. Genève, Faculte Sci. 1924, These no. 744, p. 49. [Min. Abstr., vol. 3, p. 292.]