Metamorphic rock

Metamorphic rock consists of minerals which were originally sedimentary rock or igneous rock and which have been chemically altered by heat, pressure or the introduction of other chemical substances, but which have not been remelted. This process is called metamorphism or metamorphosis.

Metamorphic rocks are sometimes revealed when plates collide (see obduction and subduction) and mountains are created.

See also: List of minerals, rock (geology)