Metamorphic rock is the result of the transformation of a pre-existing rock type in a process called metamorphism, which means "change in form".
This can occur on sedimentary rock, igneous rock or another older metamorphic rock. Examples of metamorphic rocks are slate and marble.
Metamorphic rocks are formed deep beneath the Earth's surface by great stresses resulting mainly from tectonic plate movements. The pre-existing rock is subjected to heat and extreme pressure causing dramatic physical and/or chemical change.
They are also formed by the intrusion of molten rock, called magma, into solid rock and form particularly at the place of contact between the magma and solid rock where the temperatures are high.
This video looks at Metamorphic rock
Metamorphic rocks are very hard and can be used in the construction industry. They are also used for rip rap in coastal defence schemes.
Decorative rocks such as marble can be used in homes for fireplaces and kitchen work surfaces.