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On the remarkable problem presented by the crystalline development of Calaverite

Published online by Cambridge University Press:  14 March 2018

G. F. Herbert Smith
Affiliation:
Mineral Department of the British Museum
G. T. Prior
Affiliation:
Mineral Department of the British Museum

Extract

The validity of Haüy's great law of the rationality of intercepts — better known as the law of rational indices—or its equivalent, the law of homogeneity of arrangement of the ultimate particles in a crystalline structure, has as yet never been seriously called into question : nevertheless, in the crystals of the telluride of gold, calaverite, we find characters which are to all appearance at variance with this law. As far as the author is aware and can ascertain, no difficulty of a precisely similar kind has ever been encountered before. Certain substances do, indeed, display the so-called optical anomalies; but these are, as was first established by Mallard, in reality in strict accordance with the actual crystalline arrangement.

Type
Research Article
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1902

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References

Page 122 note 1 The faces with high indices but simple mutual relations, lying in the same zone, in such a mineral as meneghinlte may possibly be due to a similar cause, but in this case the common faces present no difficulties at all.

Page 122 note 2 Re-entrant angles do occur in the prism zone, but are due to its oscillatory and striated character.

Page 123 note 1 Amer. Journ. Sci., 1868, ser. 2, vol. xlv, p. 814.

Page 123 note 2 16th Annual Report U. S. Geol. Survey, 1894-5 (1895), pt. ii, pp. 135-6 ; also Amer. Journ. Sci., 1895, set. 3, vol. 1, p. 131.

Page 123 note 3 Amer. Joura. Sci., 1901, set. 4, vol. xii, pp. 225-46 ; a German translation appeared in Zeits. Kryst. Min, 1902, vol. xxxv, pp. 430-51.

Page 124 note 1 Nature, 1901, vol. lxlil, p. 554.

Page 124 note 2 Loc. cit., p. 241.

Page 126 note 1 This Magazine, 1899, vol. xii, pp. 175-82; a translation appeared in the Zeits. Kryst. Min., 1900, vol. xxxii, pp. 209-16. Cf. also this vol., p. 75.

Page 126 note 2 This is the same notation as that employed in the papers mentioned above : A is the horizontal circle, whose axis is fixed in space ; B the vertical circle, whose axis lies in a horizontal plane ; and C the third circle, whose axis may take any direction in space.

Page 134 note 1 Miers, Cf. H. A. : ‘On a New Method of Measuring Crystals, and its Application to the Measurement of the Octahedron Angle of Potash Alum and Ammonia Alum.’ Report Brit. Assoc., 1894 (Oxford), pp. 654-5.Google Scholar

Page 134 note 2 Loc. cit., p. 243.

Page 134 note 3 Loc. cit., pp. 230 et seq.

Page 143 note 1 Amer. Journ. Sci, 1898, set. 4, vol. v, p. 376.

Page 144 note 1 Loc. cit., p. 237

Page 149 note 1 Loc. cit., p. 246.