Dive into the world of optical mineralogy with this comprehensive video lecture on the optical indicatrix, uniaxial vs biaxial minerals, and interference figures. Learn how to use the optical indicatrix and its properties to identify minerals, understand the impact of mineral grain orientation on optical properties, and explore the use of special lenses like the upper swing-in condensing lens and Bertrand lens in petrographic microscopes. Discover how to determine optic axes, optic angles, optic signs, and interference figures for mineral identification. Gain insights into uniaxial and biaxial minerals, their interference figures, and how to determine their optic signs. Conclude with a review of diagnostic properties for mineral identification and a preview of upcoming content in the mineralogy playlist.