All Earth Science students need to understand the origins, environments, and basic processes that produce igneous and metamorphic rocks. This concise introductory textbook provides students with the essential knowledge needed to understand how petrology relates to other topics in the geologic sciences, and has been written specifically for one-semester courses. Throughout, the emphasis is on interpreting the mineralogy and petrology of rock suites in terms of origin and environment, with the first half of the book concentrating on igneous rocks, and the second half on metamorphic rocks. This Second Edition has been thoroughly revised and brought completely up-to-date. It now includes a new chapter on the application of stable and radiogenic isotopes in petrology, introducing students to the concept of isotopic fractionation and describing the process of radioactive decay. The discussions of phase diagrams, connections between igneous and metamorphic rock suites, and convergent margin magmatism have also been expanded. There is a new glossary of terms, updated end-of-chapter exercises, and updated further readings.