Metamorphic rock

Facts

 * A metamorphic rock is formed because of the change of a pre-existing rock.
 * The process called metamorphism, which means "change in form."
 * The product may be sedimentary, igneous or another metamorphic rock.
 * Metamorphic rocks form only at the high temperatures and pressures.
 * Rocks that were subjected to equal pressure from all sides will not be foliated.