Fractional crystallization, or crystal fractionation, is one of the most important geochemical and physical processes operating within crust and mantle of a rocky planetary body, such as the Earth. It is important in the formation of igneous rocks because it is one of the main processes of magmatic differentiation.[1] Fractional crystallization is also important in the formation of sedimentaryevaporite rocks.
^Petrology The Study of Igneous...Rocks, Loren A. Raymond, 1995, McGraw-Hill, p. 91