The crystallization of a hydrous melt in the system K₂SiO₃—SiO₂—H₂O is studied in detail to determine what are the external factors exerting the greatest influence over the character of thefinal crystallization product. These are found to be (a) the nature of the stresses present in the crustal horizon at whichcrystallization takes place and, (b) the effective pressure of the water in the pores of the surrounding rock, a pressurewhich is determined by the potential rate of escape of vapour from the magma as well as by the gas pressure of the water itself.Various types of environment are considered and the products of consolidation of an ideal magma of this system compared forthe various cases. The probable mode of assimilation of a xenolith composed of one of the solid phases of the system in suchan ideal magma is also investigated. With this preliminary study a

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thefinal crystallization hydrous melt crustal horizon xenolith

T. C. Phemister,.The Role of Water in Basaltic Magma I.. 45 (1),19-77.

T. C. Phemister,"The Role of Water in Basaltic Magma I." 45

T. C. Phemister,"The Role of Water in Basaltic Magma I."