The literature on the geology, chemistry, and biochemistry of phosphorus generally takes its mineralogy for granted. The in­ cidental information on phosphate minerals given in these texts is often obsolescent and inaccurate. The few mineralogical texts that have dealt comprehensively with the phosphate minerals have now become outdated, and typically present the essential information in a manner unsuitable for nongeological readers. This volume is intended as a ready reference for workers who require good basic information on phosphate minerals or their synthetic equivalents. The topics covered should appeal to geologists and geochemists, lithologists, environmental scientists and engineers, chemists and biochemists who have any interest in the intricate world of phosphorus. The hard tissues of many vertebrates and the many pathological calcifications consist mostly of phosphate minerals. The precipita­ tion of these compounds also plays a major role in the ecological cycling of phosphorus, and occasionally even dominates the behavior of many trace metals in many geochemical and biolog­ ical systems. Indeed, many pegmatitic phosphate minerals have acquired some notoriety because of the rarer trace metals which they tend to accumulate. With the commercialization of phosphate fertilizers since the early part of the 19th century, phosphate minerals have assumed an important role in industrial chemistry and agriculture. Clearly, the study of phosphate minerals is important from the economic, agricultural, environmental and (human and animal) health viewpoint.