Volume 20 of Reviews in Mineralogy attempted to: (1) provide examples illustrating the
state-of-the-art in powder diffraction with emphasis on applications to geological materials
(2) describe how to obtain high-quality powder diffraction data and (3) show how to extract
maximum information from available data. In particular the nonambient experiments are examples
of some of the new and exciting areas of study using powder diffraction and the interested
reader is directed to the rapidly growing number of published papers on these subjects. Powder
diffraction has evolved to a point where considerable information can be obtained from ug-sized
samples where detection limits are in the hundreds of ppm range and where useful data can be
obtained in milliseconds to microseconds. We hope that the information in this volume will
increase the reader's access to the considerable amount of information contained in typical
diffraction data.
