The fourth edition of has been thoroughly revised and updated to increase reading comprehension and improve the clarity of its illustrations. Author William D. Nesse continues his detailed discussions of the petrographic microscope, the nature and properties of light, and the behavior of light in isotropic and anisotropic minerals, with detailed coverage of uniaxial and biaxial optics. Ideal for advanced undergraduate and graduate courses in optical mineralogy, this accessible text is also an essential resource for petrology and petrography courses.