<P> Metamorphic rocks arise from the transformation of existing rock types , in a process called metamorphism , which means `` change in form '' . The original rock ( protolith ) is subjected to heat ( temperatures greater than 150 to 200 ° C ) and pressure ( 150 megapascals ( 1,500 bar ) ) , causing profound physical or chemical change . The protolith may be a sedimentary , igneous , or existing metamorphic rock . </P>
<P> Metamorphic rocks arise from the transformation of existing rock types , in a process called metamorphism , which means `` change in form '' . The original rock ( protolith ) is subjected to heat ( temperatures greater than 150 to 200 ° C ) and pressure ( 150 megapascals ( 1,500 bar ) ) , causing profound physical or chemical change . The protolith may be a sedimentary , igneous , or existing metamorphic rock . </P>
what is any process that changes a rock 's chemical composition
what is any process that changes a rock 's chemical composition
metamorphism
metamorphism