This text describes the most important techniques for the study of opaque minerals. It covers the basic techniques of sample preparation and examination using polished sections and the polarized light microscope. The qualitative properties used for mineral identification, including textures, are examined, and numerous examples of the major mineral associations are provided. This edition has been updated to reflect new technical and theoretical developments, including new data on the most important ore types. Tables of data for the identification of the most common ore minerals are provided in the appendix.