Plagioclase cation exchange equilibria with aqueous chloride solution; results at 700 degrees C and 2000 bars in the presence of quartz

Abstract

Equil. conditions were detd. for the reaction between a synthetic plagioclase solid soln., and aq. NaCl, in the presence of excess quartz at 700° and 2000 bars: 2NaAlSi3O8 + CaCl2 .dblharw. CaAl2Si2O8 + 2NaCl + 4SiO2. The production of quartz was rapid, and equil. was closely approached in 1 day. Quartz disappearance was slow; no equil. in 30 days. For a soln. in equil., MNaCl2/MCaCl2 was const., i.e., ideal soln. behavior of aq. Cl- soln. Plagioclase solid soln. was continuous, and showed pos. deviations from ideality.