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Irregularly developed crystals of Zircon (sp. gr. 4.0) from Ceylon

Published online by Cambridge University Press:  14 March 2018

L. J. Spencer*
Affiliation:
British Museum

Extract

Some small isolated crystals from the gem-washings in Ceylon, recently sent by Mr. A. K. Coomáraswámy to the British Museum for determination and study, were at first thought to be rutile, but on detailed examination proved to be zircon of a rather unusual type. This has a specific gravity of 4.0, which is not increased when the crystals are heated.

The majority of the crystals are from the Balangoda district in the Sabaragamuwa province, and, according to Mr. Coomáraswámy have been derived from a group of zircon-granites which occur in this district; a few others are from Walaweduwa in the Bamberabotnwa district, and from the Hatton district. Associated with them are zircons of more usual types (see p. 48); the present description is, however, confined to the crystals of lower specific gravity.

Type
Research Article
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1904

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References

Page 43 note 1 Geol. Mag., 1904, new ser., dec. 5, vol. i, p. 418.

Page 44 note 1 The method of giving a plan of the crystal together with the clinographic drawing is borrowed from Robinson, H. H. (Amer. Journ. Sci., 1901, ser. 4, vol. xii, p. 180)CrossRefGoogle Scholar.

Page 46 note 1 The mean of ten approximate readings, varying between 1.9 and 2.1, was 1.97. The section has a thickness of about 1 mm.

Page 47 note 1 Zeits. Kryst. Min., 1903, vol. xxxvii, p. 252.

Page 47 note 2 Journ. Chem. Soc. London, 1864, new ser., vol. ii, pp. 389, 415; Geol. Mag., 1875, new ser., dec. 2, vol. il, p. 822; Chem. News, 1902, vol. lxxxv, p. 270.

Page 47 note 3 Zeits. Kryst. Min., 1903, vol. xxxvii, p. 247.

Page 48 note 1 Compt. Rend. Acad. Sci. Paris, 1864, vol. lviii, p. 158.

Page 48 note 2 The lowest recorded is by Stevanovié (loc. cit., p. 250), who describes greenish crystal-fragments, from Ceylon, which increase in sp. gr. from 4.33 to 4.66, at the same time losing their colour and changing from optically biaxial to uniaxial.