(NA, SR)-FELDSPARS - AN EXPERIMENTAL-STUD Y

The distribution of Na and Sr between feldspar (albite-Sr-celsian seri es) and a salt-bearing fluid at 700 degrees C and 2 kbar was studied e xperimentally. The distribution of the elements between feldspar and t he fluid is not ideal. Strontium enriches feldspar relative to the flu id over the entire compositional range. The unit cell parameters of th e albite-Sr-celsian celsian solid solutions were refined. The experime ntal data are used to calculate the excess volumes and energies of mix ing of the solid solutions of (Na,Sr)-feldspars, which are approximate d by a two-parameter Margules model.