The word "metamorphic" comes from the Greek meta meaning "to change" and morphe meaning "form." Geologically, it denotes a rock (whether sedimentary, igneous or pre-existing metamorphic rock) which has been changed in form, and therefore in structure, by heat, pressure, or a combination of the two. The heat and pressure are not sufficient to liquefy the material (so forming an igneous rock), but are sufficient to change it chemically. During this change, bedding planes and fossils are lost. Examples of metamorphic processes are:
Metamorphic rocks include:
Slate A very durable rock which is impervious, acid—and alkali – resistant, and ...