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II.—Albitization of Basic Plagioclase Felspars1

Published online by Cambridge University Press:  01 May 2009

E. B. Bailey  and
G. W. Grabham
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Extract

Since Cathrein in 1883 investigated the nature of saussurite, it has been well known that albite can arise from the alteration of basic plagioclase felspars. He found that the fine-grained aggregate of minerals known as saussurite has commonly been derived from basic felspar, and that the processes involved in the change have led to little more than a chemical re-arrangement within the limits of the original felspar crystal. The bulk composition of the aggregate thus agrees approximately with that of the felspar from which it has been derived, and the albite which separates out is intermingled with lime-bearing silicates such as epidote, zoisite, and garnet.

Type
Original Articles
Information
Geological Magazine , Volume 6 , Issue 6 , June 1909 , pp. 250 - 256
Copyright
Copyright © Cambridge University Press 1909

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Footnotes

1

By Permission of the Director of H. M. Geological Survery

References

page 250 notes 2 Zeit. Krist., 1883, Band vii, p. 234.

page 250 notes 3 “Sur l'élimination de la Chaux par métasomatose dans les roches éruptives basiques de la région du Pelvoux”: Bull. Soc. Géoi. France, 1898, vol. xxvi, pp. 165–92.Google Scholar

page 250 notes 4 “Sur les andésites et les basaltites albitisées du Cap Marsa”: Comptes Bendus, 1900, vol. cxxx, p. 96Google Scholar. Two references to the replacement of potash-felspar by secondary albite may here be inserted: Becke, F., “Zur Physiographie der Gemengteile der Krystallizen Schiefer,” Wien K. K. Akad. Wiss. Denkschr., 1906, vol. lxxv, p. 28Google Scholar; and Spencer, A. C., “The Treadwell Ore Deposits, Douglas Island,” Bull. U.S. Geol. Surv., 1904, No. 259, p. 74Google Scholar

page 251 notes 1 Although not bearing directly upon the point at issue there is much suggestive matter in Sullivan's “Interaction between Minerals and Water Solutions”, Bull. U.S. Geol. Surr., 1907, No. 312.

page 251 notes 2 It must be understood that, even if we are correct in ascribing the greater part of the albitization studied by ourselves to juvenile changes, this does not preclude the possibility of Termier's explanation holding good in other districts.

page 253 notes 1 The numbers given in parentheses refer to slides in the Geological Survey collection.

page 253 notes 2 Cf. Harker, A., “The Tertiary Igneous Rocks of Skye”: Mem. Geol. Survey, 1904, chap. iv.Google Scholar

page 254 notes 1 1 The minerals mentioned in this paragraph have, in other eases, undoubtedly arisen through weathering. It is probable that juvenile and weathering reactions frequently follow the same course, but that the former, under suitable conditions, proceed with a much greater velocity.

page 255 notes 1 “The Igneous Geology of the Bathgate and Linlithgow Hill”: Trans. Roy. Soc. Edin., 1906, vol. xlv, p. 133.Google Scholar