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II.—On a Sodalite Syenite (Ditroite) from Ice River Valley, Canadian Rocky Mountains

Published online by Cambridge University Press:  01 May 2009

T. G. Bonney
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Extract

In the year 1886 the late Dr. G. M. Dawson gave an account of a syenitic rock, rich in a beautiful blue sodalite, which he had discovered when exploring the district near Hector Pass, on the watershed of the Canadian Rocky Mountains, and an analysis of the mineral was afterwards published by Professor Harrington. The place was visited last Summer by Mr. E. Whymper during his examination of the district south of the Canada Pacific Railway, when he collected a number of specimens, which he showed to me on his return. The rock is hardly less beautiful than lapis lazuli, and as no description of its microscopic structure has been published, as far as I can ascertain, I give the results of my examination, together with a condensed account of its mode of occurrence. I am much indebted to Mr. Whymper for placing his specimens at my disposal, to Mr. L. Fletcher, Keeper of the Mineral Collection in the British Museum, for the opportunity of examining specimens of sodalite rock not in my own cabinet, and to Mr. L. J. Spencer, of that department, for giving me his kind assistance and valuable references to papers about the mineral.

Type
Original Articles
Information
Geological Magazine , Volume 9 , Issue 5 , May 1902 , pp. 199 - 206
Copyright
Copyright © Cambridge University Press 1902

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References

page 199 note 1 “Physical and Geological Features of that portion of the Rocky Mountains between lat. 49° and 51° 30′”: Geol. and Nat. Hist. Survey of Canada, 1885, p. 122, b.Google Scholar

page 199 note 2 Trans. Roy. Soc. Canada, vol. iv, sect. iii, p. 81.

page 199 note 3 Hector Pass, by which the Canada Pacific Railway crosses the watershed of the continent, was formerly called Kicking Horse Pass.

page 200 note 1 This mineral, as it happens, does not occur in the specimens which I have examined.

page 201 note 1 Mr. Whymper found a few specimens where the mineral was a pale blue.

page 201 note 2 Amer. Journ. Sci., vol. xlviii (1894), pp. 10 and 16; see also vol. xlix (1895), p. 465.Google Scholar

page 201 note 3 Professor Harrington thinks the term elæolite needless, for no line can be drawn between the specimens with the more oily and the more glassy lustre. pSo far as I have had the opportunity of judging, the distinction can hardly be maintained.

page 202 note 1 As these rocks are practically identical, one of the names should be dropped.

page 202 note 2 Described by Brögger and Backström: Zeitsch. Kryst., vol. xviii (1890), p. 222.Google Scholar

page 202 note 3 For sodalite rocks in general see Rosenbusch, “Elemente der Gesteinlehre,” 1898, pp. 115, 131. A most lucid description of the mineral sodalite is given by Fouqué & Lévy, Mineral. Micrograph., 1879, pp. 447–450.Google Scholar

page 202 note 4 The extinction angles, measured from the composition edge, are rather small.

page 202 note 5 Mineralogie Micrographique, pl. xlv, figs. 1 and 2.

page 203 note 1 I have a slice, practically all sodalite, about 1 inch long and rather less in breadth.

page 206 note 1 Fouqué & Lévy (loc. cit.) remark that the chemical formula of sodalite (allowing for the chlorine) is identical with that of nepheline. They and Rosenbusch (loc. cit.) allow that it may be a secondary mineral.

page 206 note 2 Morozewicz made sodalite artificially by fusing kaolin or nepheline with soda and excess of sodium chloride; see Journ. Chem. Soc., vol. lxxvi, pt. 2 (1899), p. 764.Google Scholar