Clarification of the Nature of the Kaolin Minerals in Hawaiian Soils

Abstract

X-ray diffraction, differential thermal and electron microscope studies were made on soils occurring under different rainfall and elevation on the Island of Oahu. A special study was also made on the lattice expansion of the Hawaiian kaolins. Kaolinite was found to be the predominant kaolin mineral in the soils studied. A relationship between the concentration of kaolin minerals as a function of rainfall and elevation was noticed. The concentration of kaolin minerals decreased with increasing rainfall and elevation. The content of kaolinite remained uniformly high in all horizons of the Low Humic Latosols but increased sharply with depth in soils which occur in the high rainfall belt. Hawaiian soil kaolinites and halloysites do not undergo lattice expansion with potassium acetate.