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The Decomposition Products of Anorthite Attacked by Pure Water at Elevated Temperatures and Pressure

Published online by Cambridge University Press:  01 January 2024

A. F. Frederickson
Affiliation:
Washington University, St. Louis, Mo., USA
J. E. Cox Jr.
Affiliation:
Washington University, St. Louis, Mo., USA

Abstract

The behavior of anorthite under the test conditions is similar to that of other feldspars and quartz. The solubility of anorthite in pure water was measured at 300 bars pressure between 200° and 350°C. Under these conditions, anorthite not only partially dissolves, but also disintegrates by shedding small particles of crystalline material which forms, with matter in true solution, a nonhomogeneous suspension. Two zeolites (afwillite and xonotlite) develop at the higher temperatures. Their stability is determined by the CaO:SiO2 ratio of the solution.

The anorthite fragments react with the solution. They maintain their identity although their composition and structure gradually change over a wide temperature range. Possibly the zeolites inherit their structure from the altered anorthite. It is almost certain that xonotlite inherits its structure from afwillite.

Type
Article
Copyright
Copyright © Clay Minerals Society 1953

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References

References Cited

Frederickson, A. F. (1951) Mechanism of Weathering: Geol. Soc. Amer. Bull., v. 62, p. 221232.CrossRefGoogle Scholar
Frederickson, A. F., and Cox, J. E. Jr. (1954a) Mechanism of “solution” of quarts in pure water at elevated pressure and temperature: Amer. Mineral, (in press).Google Scholar
Frederickson, A. F., and Cox, J. E. Jr. (1954b) “Solubility” of albite in hydrothermal solutions: Amer. Mineral, (in press).Google Scholar