ORTHOSILICATES

A second edition, in two parts, of Volume 1 of this well-known reference series. This volume deals mainly with the olivine and garnet groups and also the humitegroup, zircon, sphene, vesuvianite, the Al2SiO5 (including mullite), topaz, staurolite and chloritoid. The disilicates and ring-silicates are covered in Volume 1B. In the years since the first edition was published, the quantity and scope of research on the olivines, garnets and the aluminosilicates has grown enormously and has given rise to a wide variety of literature. This book, which has been completely rewritten and considerably expanded, summarizes the important research results and presents them in an organized fashion. Each mineral chapter is divided into sections on structure, chemistry, optical and physical properties, distinguishing features and paragenesis. Each chapter is headed by a tabulation of mineral data and a sketch showing optical orientation, and concludes with full references to the literature. Diagrams of the crystal structures are presented and are followed by a discussion of the structural features. The chemical sections include a large number of analyses from which structural formulae have been calculated, illustrating the chemical and paragenetical variation exhibited by each mineral; phase equilibria in relevant systems are fully considered. In the sections on optical and physical properties, particular attention is paid to the correlation of these properties with chemical composition. The principal modes of occurrence are described and discussed in the paragenesis sections; here again correlation with chemistry is emphasized.