Clay minerals form in a wide variety of crustal environments, e.g. in soil profiles, in sediments at the surface and in deeply buried sedimentary deposits, and under regional, contact and hydrothermal metamorphism conditions. The book provides information about the dynamics of isotope systems in clays and helps us to understand the physical and chemical parameters in the transfer of masses within the crustal domain. Written for graduate students taking courses in sedimentary geochemistry, clay mineralogy, and soil mineralogy, the book will also appeal to scientists carrying out research on clay genesis and mass transfer in crustal environments.