THE CLAY MINERAL CONCEPT

IT IS NOW GENERALLY AGREED THAT SOILS, CLAYS, AND SHALES ARE COMPOSED OF EXTREMELY SMALL PARTICLES OF A FEW MINERALS KNOWN AS THE CLAY MINERALS. CLAY MINERALS ARE GENERALLY CRYSTALLINE - SOME CLAYS CONTAIN MATERIAL AMORPHOUS TO DIFFRACTION TECHNIQUES, BUT SUCH MATERIAL IS BELIEVED TO BE RELATIVELY RARE. STRUCTURE AND COMPOSITION OF THE CLAY MINERALS DETERMINE THEIR PROPERTIES WHICH IN TURN LARGELY DETERMINE BULK PROPERTIES OF THE CLAY ITSELF. CLAY MINERAL COMPOSITION OF ARGILLACEOUS MATERIAL IS OFTEN COMPLEX BECAUSE OF THE MIXING OF MINERALS INDISCRETE PARTICLES AND/ OR AS MIXED-LAYER ASSEMBLAGES. STRUCTURE AND COMPOSITION ARE BRIEFLY REVIEWED FROM THE POINT OF VIEW OF THE INFLUENCE OF THE ATOMIC ARRANGEMENT AND DEGREE OF STRUCTURAL ORDER ON PHYSICAL PROPERTIES. CERTAIN CHARACTERISTICS OF THE CLAY MINERALS, SUCH AS ION EXCHANGE, WATER ABSORPTION, AND REACTION WITH ORGANIC COMPOUNDS, ARE OF A SPECIAL INTEREST IN A CONSIDERATION OF THE CERAMIC PROPERTIES OF CLAY. /AUTHOR/