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This section is not intended to provide a comprehensive glossary of terms used in this book. There are, however, several terms that are used throughout the text where a definition is either useful or necessary in order to avoid ambiguity. The following definitions are consistent with those provided in the Glossary of Geology (Bates and Jackson 1987) and The Encyclopedia of the Solid Earth Sciences (Kearey 1993).

 Ore: any naturally occurring material from which a mineral or aggregate of value can be extracted at a profit. In this book the concept extends to coal (a combustible rock comprising more than 50% by weight carbonaceous material) and petroleum (naturally occurring hydrocarbon in gaseous, liquid, or solid state).

 Syngenetic: refers to ore deposits that form at the same time as their host rocks. In this book this includes deposits that form during the early stages of sediment diagenesis.

 Epigenetic: refers to ore deposits that form after their host rocks.

 Hypogene: refers to mineralization caused by ascending hydrothermal solutions.

 Supergene: refers to mineralization caused by descending solutions. The term generally refers to the enrichment processes accompanying the weathering and oxidation of sulfide and oxide ores at or near the surface.

 Metallogeny: the study of the genesis of mineral deposits, with emphasis on their relationships in space and time to geological features of the Earth's crust.

 Metallotect: any geological, tectonic, lithological, or geochemical feature that has played a role in the concentration of one or more elements in the Earth's crust.

 Metallogenic Epoch: a unit of geologic time favorable for the deposition of ores or characterized by a particular assemblage of deposit types.

 Metallogenic Province: a region characterized by a particular assemblage of mineral deposit types.

 Epithermal: hydrothermal ore deposits formed at shallow depths (less than 1500 m) and fairly low temperatures (50–200 °C).

 Mesothermal: hydrothermal ore deposits formed at intermediate depths (1500–5000 m) and temperatures (200–400 °C).

 Hypothermal: hydrothermal ore deposits formed at substantial depths (greater than 5000 m) and elevated temperatures (400–600 °C).