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On the relation of chamosite and daphnite to the chlorite group1 (With Plates XVIII and XIX.)

Published online by Cambridge University Press:  14 March 2018

A. F. Hallimond*
Affiliation:
Museum of Practical Geology, London

Extract

There is a close optical and chemical resemblance between chamosite, the chloritic mineral of the bedded ironstones, and daphnite, a low-temperature vein-chlorite common in some of the Cornish tin mines. New material has made it possible to undertake a fresh comparison of the two minerals: chemical analyses have been made by Mr. C. O. Harvey, chemist to H.M. Geological Survey, and a report on the X-ray measurements is contributed by Mr. F. A. Bannister, of the Mineral Department of the British Museum.

The new analysis of chamosite agrees with the simple formula previously assigned: X-ray examination of material from several localities has now established the distinctive crystalline nature of this fine-grained mineral, which differs structurally from ordinary chlorites such as clinochlore. Daphnite, on the other hand, has the ordinary chlorite structure, but the new analysis fully confirms Tschermak's original opinion that it cannot be represented chemically as a mixture of serpentine and amesite.

Type
Research Article
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1939

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Footnotes

1

Published by permission of the Director, Geological Survey and Museum.

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