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A Study of Possible Factors concerning Garnet Formation in Rocks from Ardara, Co. Donegal, Ireland

Published online by Cambridge University Press:  01 May 2009

K. A. Jones  and
A. K. Galwey
K. A. Jones
Affiliation:
Dept. of Geology (K. A. J.) and Dept. of Chemistry (A. K. G.), The Queen's University, Belfast.
A. K. Galwey
Affiliation:
Dept. of Geology (K. A. J.) and Dept. of Chemistry (A. K. G.), The Queen's University, Belfast.
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Abstract

Chemical and modal analyses have been made for a series of ten homogeneous specimens of meta-sediments, with identical metamorphic histories, from the aureôle of the Ardara pluton. Results showed that total amount of garnet was determined by the quanity of “free ferrous oxide” (assuming that the reaction: FeO + Fe2O3→ Fe3O4, has gone to completion) in the rock. Size distribution curves showed that each specimen contained crystals with a preferred radius and throughout the series a quantitative relation between the preferred radius and the frequency distribution about this value was observed.

Measurement of the number of crystals per unit volume showed that this gave trends with functions of the chemical composition of the rock. A discussion of the mechanism of garnet formation in terms of chemical laws of nucleation and growth is given.

Type
Articles
Information
Geological Magazine , Volume 101 , Issue 1 , 06 February 1964 , pp. 76 - 93
Copyright
Copyright © Cambridge University Press 1964

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References

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