Clay minerals
Pure clay minerals were selected for comparison to the clay fraction in the selected soils. Illite and kaolinite clay minerals were obtained from Washington State University’s mineral collection and were pulverized prior to obtain a mean particle size between 25 and 2 mm. Beidellite clay (Bid-1) was purchased from the Clay Mineral Repository and pulverized prior to use (University of Missouri, St. Louis, MO).