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On crossite from Anglesey

Published online by Cambridge University Press:  14 March 2018

Norman Holgate
Norman Holgate*
Affiliation:
Department of Geology, University of Glasgow
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Extract

The occurrence of a member of the glaucophane group of minerals in Anglesey has been known since 1888, in which year Blake reported the presence of a blue amphibole in a schist exposed in the neighbourhood of the Anglesey Column, west of the Menai Bridge. In the course of his paper Blake made general remarks on the petrography of the schist and on its field relations. He dwelt at some length on the question of the identity of the blue amphibole which is its most notable constituent, describing its columnar habit and pleochroism, and recording an extinction angle of 15° with the axis of elongation (c). By comparison with a description of glaucophane due to Rosenbusch, Blake concluded that the blue amphibole from the Anglesey rock is a normal glaucophane, although it, an extinction angle as recorded by him is considerably in excess of the 4° to 6° mentioned by Rosenbusch.

Type
Research Article
Information
Mineralogical magazine and journal of the Mineralogical Society , Volume 29 , Issue 215 , December 1951 , pp. 792 - 798
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1951

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References

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