Many common terms in metamorphic petrology vary in their usage and meaning between countries. The International Union of Geological Sciences (IUGS) Subcommission on the Systematics of Metamorphic Rocks (SCMR) has aimed to resolve this, and to present systematic terminology and rock definitions that can be used worldwide. This 2007 book is the result of discussion and consultation lasting 20 years and involving hundreds of geoscientists worldwide. It presents a complete nomenclature of metamorphic rocks, with a comprehensive glossary of definitions, sources and etymology of over 1200 terms, and a list of mineral abbreviations. Twelve multi-authored sections explain how to derive the correct names for metamorphic rocks and processes, and discuss the rationale behind the more important terms. These sections deal with rocks from high- to low- and very-low-grade. This book will form a key reference and international standard for all geoscientists studying metamorphic rocks.