This manual consists of a total of seven individual volumes. Scientists appointed by the Federal Institute for Geosciences and Natural Resources compile the work based on various combinations of methods, taking into account scientific fundamentals and information. This volume deals with the investigation of the material properties of the subsoil of landfills and contaminated sites, providing, after fundamental information about clay minerals, clays, and clay rocks and their pollutant retention capacity, an overview of the available range of methods, examination possibilities, and evaluation criteria. Extensive literature citations and references to further literature complete this volume.