i) Petrology: Formation of various types of rocks, their mode of occurrence, composition, texture and structures, geological and geographical distribution on the earth are all studied under petrology. It is one of the important subdivisions of geology and is further subdivided into distinct branches: Igneous petrography, Sedimentary petrology and metamorphic petrology.
ii) Mineralogy: Mineralogy is that branch of geology, which deals with formation, occurrence, aggregation, properties, and uses of minerals. Mineralogy sometimes itself divided into specific sub-branches such as crystallography, optical mineralogy and descriptive mineralogy and so on.