Fabric (texture and structure) and minpralogic composition determine the response of clays and shales to events occurrins during construction and operation of engineering works. A new system of classification of the fabric of earth materials is proposed. Characteristic minpralogic composition of clays and shales, especially in the western United States, is described. Fabric and composition are correlated with soil mechanics properties and engineering performance. Needed research on clays and shales as a basis for design, construction, and maintenance of engineering structures is emphasized.

Clays are used in the ceramics industries largely because of their contribution to the moulding and drying properties of the wares being produced; many clays, such as the flint clays, are used because of favorable behavior during firing or because they produce favorable properties in fired ware.

To assure the most effective use of a clay, the ceramic technologist must meet problems of purification, aging, bacterial action, and the improvement of the working properties of clays and bodies through additions of non-plastic materials or chemicals. He deals with flocculation and deflocculation, thixotropy, and related phenomena in casting slips. Control of drying behavior is important. Finally, the ceramist is concerned with the influence of the clay content of ceramic bodies on their behavior during firing.