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The hydration of larnite (β-Ca2SiO4) and bredigite (α1-Ca2SiO4) and the properties of the resulting gelatinous mineral plombierite

Published online by Cambridge University Press:  14 March 2018

J. D. C. McConnell*
Affiliation:
Department of Mineralogy and Petrology, University of Cambridge

Abstract

In this paper the formation of a gelatinous hydrate phase from the natural dicalcium silicate minerals larnite and bredigite is described. Detailed study of the gel so formed indicates that the process of hydration is a solid reaction which is effeeted by diffusion. The preferred orientation of the hydrate phase suggests that the hydration is facilitated by a relationship between the structure of the anhydrous silicate and that of the hydrate phase produced.

In this investigation the variations in density, mean refractive index, and chemical composition of the natural gels have been determined and the characteristics of the adsorbed water studied by isothermal dehydration and rehydration. In discussing the mechanism of hydration it has been assumed that this obtains at constant volume. This assumption is based on the study of gel pseudomorphs after single crystals of larnite and bredigite in thin section.

Type
Research Article
Copyright
Copyright © 1955, The Mineralogical Society

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