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A simple graphic method for determining extinction-angles in sections of biaxial crystals

Published online by Cambridge University Press:  14 March 2018

H. G. Smith*
Affiliation:
Imperial College of Science and Technology

Extract

The relationship between the optic axes and the vibration-directions in a section of a biaxial crystal was enunciated by Biot in 1819, and may be stated as follows : The vibration-directions in any section of a biaxial crystal are given by the bisectors of the angles between the optic axes as projected on the plane of section.

Dr. Fletcher and Mr. Harker have elaborated the idea, but there appears to be room for a simpler presentment, more adapted to the needs of students, which does not involve the use of the optical indicatrix or the spherical projection.

Type
Research Article
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1912

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References

Page 232 note 1 Blot, J. B., ‘Sur les lois générales de la double réfraction et de la polarisation dana lea corps régulièrement cristallisés,’ Mém. Acad. Royale des Sci., Institut de France. 1820, vol. iii (annie 1818), pp. 177384 Google Scholar.

Page 232 note 2 Fletcher, L., ‘The optical indicatrix and the transmission of light in crystals,’ Mineralogical Magazine, 1891, vol. ix, pp. 278888 (see p: 341)CrossRefGoogle Scholar.

Page 232 note 3 Harker, A., ‘Extinction-angles in cleavage-flakes’ Mineralogical Magazine, 1898, vol. x, pp. 289–240Google Scholar.