Optical Mineralogy is the study of minerals using light and optical techniques. It involves examining the properties of minerals under a microscope, particularly how they interact with polarized light. This helps identify minerals based on their optical characteristics, such as color, birefringence, and pleochroism. In petrology, optical mineralogy plays a crucial role in understanding the composition and formation of rocks. By analyzing thin sections of rock samples, geologists can determine the types of minerals present and their relationships, providing insights into geological processes and the history of the Earth's crust.