During the formation and development process of crust, the re-combination of mineral composition, texture and structure occurred to the previously formed rocks, including magmatic rocks, sedimentary rocks and first-formed metamorphic rocks, even including changes of chemical composition, in the case of the solid state in order to adapt to the new conditions of geological environment and physical and chemical changes. This change process is called metamorphism. The rocks formed as a result of metamorphism are known as metamorphic rocks.