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An unusual occurrence of quartz and amorphous silica at Carmean, Moneymore, Co. Antrim

Published online by Cambridge University Press:  01 May 2009

J. Preston
Affiliation:
Department of Geology, The Queen's University of Belfast, Belfast BT7 1NN, Northern Ireland

Summary

Cavities in Cretaceous chalk, Co. Antrim, contain spongy silica. SEM photographs show minute doubly terminated quartz crystals trapped in fibrous mats of amorphous silica. The absence of both opal diffraction lines and a globular structure indicate the prior existence of gelatinous silica which prevented settling of the suspended quartz crystals. Drying and shrinkage of the gel produced the spongy deposit.

Type
Articles
Copyright
Copyright © Cambridge University Press 1977

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