READING NESSE: Pages 116-118, Interaction of Light and Matter, Anisotropic versus Isotropic, Reflection and Refraction, Dispersion and Prisms. ASSIGNED: Also read these sections from Gregg Finn's Brock University Optical Mineralogy Page. Reflection and Refraction You need to understand reflection and refraction. Of particular importance will be which way light bends going from a denser material into a less dense material or the opposite, less dense into dense. Be able to use Snell's law and understand roughly how it is derived. Understand what the critical angle is and how light inside of a denser media may be reflected. Also understand the difference between an Isotropic mineral with only one index of refraction, and anisotropic minerals that have multiple indices of refraction.