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Curvature in Crystals

Published online by Cambridge University Press:  14 March 2018

L. J. Spencer*
Affiliation:
British Museum

Extract

The following notes were prepared at the request of Dr. J. E. Stead, F.R.S., the well-known metallographer. Several years ago he had obtained in a tin-antimony-arsenic alloy some remarkable crystals having the form of seganents of spherical shells (fig. 3, p. 9.72 below), and he naturally wished to learn if anything of the same kind was known amongst minerals. The notes contain no new data, but merely collect together facts already known to mineralogists. They may perhaps be of some use to metallographers in calling attention to the various habits of growth met with amongst minerals, since distortions and irregularities of crystalline growth are so frequent amongst metals.

Type
Research Article
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1921

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References

1 Specimens were shown at the Royal Society's Conversaziono in 1906, and the complete description is given in the paper 'The ternary alloys of tinantimony-arsenic', by J. E. Stead, with notes byL. J. Speneer, Journ. Institute of Metals, London, 1919, vol. 22 (no. 2 for 1919), pp. 127-1449 10 pls. ; reprinted (from the uncorrected proofs] in Engineering, London, 1919 vol. 108, pp. 663-667 [Min. Abstr., vol. 1, p. 281]. In the discussion (pp. 145-148) on this paper Prof. Carl A. F. Bonedicks offers an ingenious explanation of the curvature of the spherical shells, basing it on differences in the dilatation-coefficient corresponding with variations in chemical composition of the lamellar mixed crystal during growth.