The aim of this comprehenvise book is to present the most important results achieved in the research of the clay minerals palygorskite and sepiolite. Palygorskite and sepiolite have found to be useful in a huge variety of industrial and medical applications. As a result, research on these clays has been intensified during the last two decades, and important advances in their characterization have been made. The book contains contributions from distinguished scientists in the field.