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On the changed composition of an anorthoclase-bearing rock-glass1

Published online by Cambridge University Press:  14 March 2018

L. Hawkes  and
H. F. Harwood
L. Hawkes
Affiliation:
Bedford College, London University
H. F. Harwood
Affiliation:
Bedford College, London University
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Extract

The present investigation began with an attempt to isolate and analyse the small sparse anorthoclase insets (t)henocrysts) of the chilled glassy selvage of a felsite dike. On comparison of the compositions of the insets and the host rock it was found that the relationship was abnormal and that the insets could not have grown in a magma represented by the glass. The composition of the felsite interior of the dike, however, represents a magma which could have yielded the anorthoclase, and full consideration leads to the conclusion that the glass, though absolutely fresh and unaltered in appearance, has suffered marked changes in composition.

Type
Research Article
Information
Mineralogical magazine and journal of the Mineralogical Society , Volume 23 , Issue 138 , September 1932 , pp. 163 - 174
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1932 

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Footnotes

1

Unless otherwise stated, the chemical analyses given in this paper were made by Dr. H. F. Harwood. The remainder of the work was carried out by Dr. L. Hawkcs who has written the paper

References

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page 167 note 1 Glassy contact facies of the dike. Jafnadal, StoSvarfjord, Iceland.

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