What is Metamorphic rock?
[[File:Calcite-Spinel-dtn37a.jpg|thumb|250px|right|Spinel: a small spinel crystal on top of a white calcite from Mogok, [[Myanmar]]. This is a metamorphic mineral]] [[File:Quartzite.jpg|thumb|250px|right|Quartzite, a form of metamorphic [[sandstone]]]] [[File:Migma ss 2006.jpg|thumb|250px|Folded strata in a metamorphic rock from near [[Geirangerfjord]], [[Norway]]]] A '''metamorphic rock''' is a type of [[Rock (geology)|rock]] which has been changed by extreme [[heat]] and [[pressure]]. Its name is from 'morph' (meaning form), and 'meta' (meaning change).<ref>This originally [[Greek language|Greek]] [[prefix]] has several meanings, but here it means 'change'.</ref> The original rock gets heated (temperatures greater than 150 to 200&nbsp;°C) and pressured (1500 [[Barometric pressure|bars]]).<ref>Blatt, Harvey and Robert J. Tracy, 1996. ''Petrology''. 2nd ed, W.H.Freeman, p.355. {{ISBN|0-7167-2438-3}}</ref> This causes profound physical and/or chemical change. The original rock may be [[sedimentary rock]], [[igneous rock]] or another older metamorphic rock. There is always more pressure and higher temperature under the Earth's surface. In the root of a [[mountain]] chain or a [[volcano]] these forces will be enough to change shape of the [[strata]] and the [[mineral]]s it is made of. Sedimentary rock which has been near such forces often looks as if a [[giant]] had twisted it and heated it over a fire. Examples of metamorphic rock: * [[Marble]] is a metamorphic rock formed from [[limestone]]. * [[Slate]] is a metamorphic [[mudstone]] or [[shale]]. * [[Quartzite]] is a metamorphic [[sandstone]]. The recrystallisation of minerals after heating generally causes the destruction of any [[fossil]]s the rocks might have contained. These rocks are formed when igneous or sedimentary rocks are subjected to extreme heat and pressure. As a result, they undergo a complete change in their form and characteristics. Rocks who have been changed in this way are called metamorphic rocks. == Types of metamorphism == ===Regional m