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On some crystals of Quartz from De Aar (Cape Colony) and other localities

Published online by Cambridge University Press:  14 March 2018

Extract

A Small set of quartz crystals of somewhat peculiar habit, collected by Lieut. E. G. Spencer-Churchill near De Aar, South Africa, and given by him to the Mineral Department of the University Museum, present some features of interest; two crystals, in particular, are remarkable as exhibiting faces seldom observed on quartz. The first has a face X lying in the zone [mz] (or [mr]?), the other a well-developed face in the zone [rz].

The crystal bearing the former face, X, is depicted in fig. 1. As regards habit and other features, it is in all respects similar to the second crystal (fig. 2).

The faces r and z cannot be distinguished with certainty, but cleavage-cracks within the crystal point to the lettering shown in fig. 1. The polariscope proves the presence of both right- and left-handed material.

Type
Research Article
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1903

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References

Page 332 note 1 Ann. Phys. Chem. (Poggendorff), 1856, vol. xcix, p. 296.

Page 333 note 1 ‘Minéralogie de la France,’ 1901, Tome iii, Fasc. 1, p. 100.

Page 334 note 1 Bull. Soc. franç, Min., 1902, vol. xxv, p. 62.

Page 335 note 1 Bull. Soc. franç. Min., 1902, vol. xxv, p. 61.

Page 335 note 2 Bull. Soc. franç. Min., 1899, vol. xxii, p. 97.

Page 335 note 3 Ibid., p. 93, fig. 1, and p. 124, fig. 1.

Page 335 note 4 Mineralogy, 1902, p. 66.

Page 335 note 5 Crystallography, 1899, p. 454.