Metamorphic rocks are the transformation of the existing rocks, the protolith through the process of metamorphism. The Protoliths can be the igneous rock, sedimentary rock or any old metamorphic rock. Due to severe heat and pressure, the protolithis get various chemical or physical changes. These rocks create a huge part of the Earth's crust and these can be classified by the mineral and chemical assemblage and by the textures. Examples of the metamorphic rocks are: slate, gneiss, schist, marble and quartzite.
Formation of the metamorphic rocks:
The metamorphic rocks are created deep beneath the surface of the Earth because of high temperatures and because of the huge pressure of the layers of the rocks above it. Another process of the formation of the metamorphic rocks is the tectonic process like the continental collision which leads to the horizontal pressure, distortion and friction. Metamorphic rocks can also be formed while any rock gets heated up by the invasion of Magma from the interior part of the Earth.
Minerals which can be found in the metamorphic rocks:
Due to the high pressure and high temperature, minerals are usually found in the metamorphic rocks. The minerals are known as the index minerals and it includes: kyanite, silimanite, staurolite, some garnet and the andalusite. Some other minerals like olivines, amphiboles, pyroxenes, mica, quartz and feldspars can also be found sometimes in the metamorphic rocks. But they are not necessarily the result of the metamorphism process.
Recrystallization and metamorphism:
During the metamorphism process, the change in the rocks particle size is called the recrystallization. As an example, through the process of recrystallization, the limestone crystals change into marbles which are made of larger crystals. The pressure and high temperature, both contribute to the recrystallization process. The high temperatures allow the ions and atoms in the solid crystals to migrate and therefore to...
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