Metamorphic refers to a type of rock that has undergone a transformation due to heat, pressure, or chemically active fluids. This process, known as metamorphism, alters the mineral composition and structure of the original rock, which can be either igneous or sedimentary. Common examples of metamorphic rocks include schist, gneiss, and marble. Metamorphic rocks are typically found deep within the Earth's crust, where conditions are suitable for these changes to occur. The study of metamorphic rocks helps geologists understand the geological history and processes that shape the Earth. They can also provide insights into the conditions present during their formation.