Book excerpt: In a sense, all mineralogy is environmental mineralogy. However, the term environmental has come to be employed (particularly in combination with terms such as science, issue or problem) to refer to those systems at or near the surface of the Earth where the geosphere comes into contact with the hydrosphere, atmosphere and biosphere. This is, of course, the environment upon which the human race depends for survival and, hence, is now sometimes referred to as the critical zone. Those systems containing minerals that constitute the most important or key environments are considered here: soils, modern sediments, atmospheric aerosols, and the interior or exterior parts of certain micro- and macro-organisms. Particularly important are the roles that minerals play in processes that act over time to control or influence the environment at various scales of observation. Both pure systems and those contaminated as a result of human activity are considered. The objectives for this volume are to help to define the subject of environmental mineralogy, and to provide an initial source of information both for mineralogists and other scientists who wish to understand or work in this field. It was hoped that it might also provide a text for use by those teaching courses in the subject at advanced undergraduate or graduate student level.