Plan of Review This review of clay microstructure is aimed at the diverse group of professionals who share an interest in the properties of fine-grained minerals in sediments. During the last several decades, members of this group have included geologists, soil scientists, soil engineers, engineering geologists, and ceramics scientists. More recently, it has included significant numbers of marine geologists and other engineers. Each of the disciplines has developed special techniques for investigating properties of clay sediments that have proven to be fruitful in answering questions of...