The volume Rare Earth Elements C 12/b deals mainly with the carbonates, oxide and hydroxide carbonates, alkali carbonates, thiocyanates, alkali and alkyl ammonium thiocyanates of the rare earth elements. Cyanides, cyanates, and selenocyanates of the rare earth elements are less extensively studied and described in some smaller sections. Major chapters are devoted to the preparation of carbonates, basic carbonates, and alkali rare earth carbonates by various procedures, and to characterize the compounds by crystallographic and IR spectroscopic methods. Another large chapter covers the preparation and some interesting physical properties of rare earth thiocyanates, alkali and alkyl ammonium rare earth thiocyanates, as well as adducts with some organic solvents.