The second edition of this classic book provides an updated look at crystal field theory - one of the simplest models of chemical bonding - and its applications. Crystal field theory provides a link between the visible region spectra and thermodynamic properties of numerous rock-forming minerals and gems that contain the elements iron, titanium, vanadium, chromium, manganese, cobalt, nickel or copper. These elements are major constituents of terrestrial planets and significantly influence their geochemical and geophysical properties. A unique perspective of the second edition is that it highlights the properties of minerals that make them compounds of interest to solid-state chemists and physicists as well as to all earth and planetary scientists. This book will be useful as a textbook for advanced students as well as a valuable reference work for all research workers interested in this subject.