POTASSIUM FIXATION IN CLAY MINERALS AS RELATED TO CRYSTAL STRUCTURE

Abstract

The total amt. of K fixed in 21 type clay minerals apparently increases with increasing tetrahedral charge. The order of increasing crystal lattice K for minerals studied was: Calif. bentonite, Wyo. bentonite, Putnam clay, and illite. Calculation of the max. oxygen radius for stable 14-fold coordination with alkali metals in the hexagonal oxygen networks of the clay surfaces showed that the value for such coordination with K is exactly 1.4 A., the observed value. K seems to form the most stable configuration; Rb and Na form less stable configurations, Cs and Li nonstable configurations in 14-fold coordination with oxygen.