Transformation of minerals of the montmorillonite family into 10 Å. micas

In his work on the mineralogy of soils colloids G. Nagelschmidt, suggests the possibility of a reversible change of the type montmorillonite ⇋ illite ⇋ muscovite. We have attempted to establish experimentally the existence of this transformation following fixation or departure of the potassium from between the fundamental structural sheets of the mica type. The initial material was montmorillonite from Camp Bertaux, Morocco, separated from its impurities by sedimentation. As it was evident a priori that the alteration of montmorillonite into illite necessitates (1) saturation of the base-exchange capacity of the minerals by potassium, and (2) the departure of the layers of water from between the structural sheets of the montmorillonite, we finally, after several attempts, were led to make use of the following technique.