Geochemistry concerns the distribution and migration of chemical elements within the Earth, but it comprises much more defined challenges such as the study of the origin of chemical elements, their evolution, the formation of minerals and rocks minerals, and also the role of elements in biology (geobiology). From the beginning, geochemistry has undergone very important advances, especially in the twentieth century which include the study of both the interior and crust of the Earth, the composition of the atmosphere, interaction with living organisms, and the distribution of elements in the Solar System and planets. Modern geochemistry can be applied to nearly all of the Earth Sciences. This book includes chapters discussing the use of geochemistry in environmental geochemistry, the correlation of geological materials, use of rare earths, the study of clays, and the biogeochemistry of petrological applications of geochemistry.