Phase equilibria of some minerals in the K 2 O-Na 2 O-Al 2 O 3 -SiO 2 -H 2 O system at 25 degrees C and 1 atmosphere

Abstract

Phase equilibria in the above system are depicted graphically in terms of the parameters log K (super +) /H (super +) , log Na (super +) /H (super +) , and log SiO ₂ at 25 degrees C and on the chemistry of the coexisting aqueous phase are used to construct the phase diagram. Two phase boundaries are based on recent laboratory investigations by Hemley (1959) and Hemley, Meyer, and Richter (1961). The results show that K-mica, K-spar, montmorillonite, and phillipsite are all stable in an environment chemically equivalent to that existing in oceanic sediments. The kaolinite field is favored by lower alkali /H (super +) ratios while gibbsite is restricted to systems that contain extremely low silica values, probably less than 1 ppm. Albite and analcite are indicative of high log Na (super +) /H (super +) concentrations.