- GeoRef, Copyright 2008, American Geological Institute. Reference includes data from Bibliography and Index of North American Geology, U. S. Geological Survey, Reston, VA, United States
Much of the clay material in Recent and Tertiary sediments has been found to contain interlayer mixtures of three clay mineral types. An analytical method to determine the quantities of each clay mineral type in this kind of mixture involves gathering diffraction data from oriented aggregate specimens in equilibrium with 50% RH together with data from the specimen either after heating or solvating with ethylene glycol. The method provides precision commensurate with that of data which are obtained from this kind of clay material.