Petrology is the study of rocks - igneous, metamorphic, and sedimentary - and the processes that form and transform them. Mineralogy is the study of the chemistry, crystal structure and physical properties of the mineral constituents of rocks. Both petrological and mineralogical processes are sensitive to environmental conditions, so the compositions of rocks, and the minerals they consist of, are interrogated to answer fundamental questions across a wide range of geological disciplines.<br><br>At CU Boulder, we use petrology to study the formation of volcanoes and their magmatic sources, the evolution of continental crust during the growth and destruction of mountain belts, the genesis of accessory minerals such as REE phosphates in all rock types, the origins of economic concentrations of minerals and petroleum, the make-up of the atmosphere, ocean and life on Earth through time, and the geological processes that occur on other planets.