Light lanthanoid partitioning in rocks and materials containing rare earths

An extensive survey of geochemical literature has been made. The information obtained has been condensed to illustrate the various factors which control partitioning of the chemically similar light lanthanoid elements in rocks and minerals formed under different geochemical conditions. The reasons for partitioning may be classified under one or more of the following categories: (1) ionic radius differences, (2) crystal structures, (3) basicity differences, (4) oxidation states, (5) stability of complexes. Although the actual differences are often small in quantity, these small differences may shift the chemical equilibrium and allow partitioning