Evidence is presented to show that the big potash feldspars in the aplite-pegmatite complex at Tremearne and in the Carnmenellis granite in western Cornwall have grown in solid or nearly solid rock. It is considered that the rocks present before metasomatism were aplitic and that these rocks have been permeated by a fluid phase containing potassium; there is evidence that this dispersed phase caused the metasomatism and re-crystallization of the aplitic rocks to produce porphyritic granite and pegmatite. These conclusions can be extended to other granitic rocks of southwest England.
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Stone et al. (1961) studied this question.