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The thermal decomposition of afwillite

Published online by Cambridge University Press:  14 March 2018

K. M. Moody*
Affiliation:
Crystallographic Laboratory, Cavendish Laboratory, Cambridge

Extract

The mineral afwillite is one of the hydrated calcium silicates which are found in set cements. It has the empirical formula 3CaO.2SiO2.3H20; a recent determination of the structure by Megaw (in press) has shown that the structural formula is Cas(SiO3OH)2. 2H2O, the hydroxyl groups being linked directly to silicon atoms. When afwillite is heated it loses water. Parry and Wright observed that practically all the water could be driven off by heating for prolonged periods at 300° C., or for shorter periods at higher temperatures. They also found that a further reaction took place on heating to about 1300° C. The present work was undertaken to investigate these changes, and to identify the products formed, using-X-ray powder methods.

Type
Research Article
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1952

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References

page 838 note 2 Parry, J. and Wright, F. E, Min. Mag., 1925, vol. 20, p. 277 Google Scholar.

page 839 note 1 Taylor, H. F. W., Journ. Chem. Soc. London, 1950, p. 3682. [M.A. 11–314.]Google Scholar

page 839 note 2 Tilley, C. E., Min. Mag., 1942, vol. 26, p. 190 Google Scholar.

page 839 note 3 Flint, E. Y., MeMurdie, H. F., and Wells, L. S., Journ. Res. Nat. Bur. Standards U.S.A., 1938, vol. 21, p. 628. [M.A. 7283.]Google Scholar

page 840 note 1 Megaw, H. D., Acta Cryst., 1949, vol. 2, p. 419 Google Scholar. [M.A. 11–430.]