A clear understanding of the processes responsible for observed rock microstructures is essential for making reliable petrogenetic interpretations, including inferences made from chemical and isotopic analyses of minerals. This volume presents a comprehensive survey of rock microstructures, emphasising basic concepts and the latest methods, while highlighting potential pitfalls in the interpretation of the origin of rock microstructure. Richly illustrated with over 250 colour photographs, including more than 10 percent new photomicrographs and several mesoscopic images, it demonstrates the basic processes responsible for the wide variety of microstructures in igneous, metamorphic and sedimentary rocks. This second edition includes extensive updates to the coverage of igneous rocks as well as recent ideas on physical processes in migmatites and partial melting of sedimentary rocks. This practical guide will continue to be an invaluable resource to advanced students and early-career researchers of mineralogy, petrology and structural geology, as well as professional geologists and material scientists.