The principal objective of this course is to enable you to identify and interpret the most common rocks forming minerals. The study of minerals is important to geologists, because minerals compose rocks. The proper identification of rocks (e.g., sedimentary, igneous, or metamorphic rocks) requires the ability to identify the constituent minerals. Naturally this identification is only the first step toward an interpretation of the rocks. Mineralogy is a subject that goes beyond mere mineral identification. Knowledge of symmetry, twinning, phase equilibria, crystal chemistry helps us to interpret the conditions of formation of a mineral as well as other events that a mineral has experienced.