Metamorphic Ore Deposits
Metamorphic rocks are formed from heat and fluids near cooling magma (contact metamorphism) and by high temperatures and pressures deep with the crust (regional metamorphism). Although rock metamorphism certainly plays an important role in ore deposition, most of the resulting deposits are classified as hydrothermal. Relatively few ore deposits actually form in regionally metamorphosed rocks, but regional metamorphism drives water and other volatile components from the rock to form hydrothermal fluids responsible for ore deposits elsewhere. Contact metamorphic rocks contain a wide variety of ore deposits, but because hot fluids are commonly involved, they are generally considered to be part of the hydrothermal realm.