Metamorphic rocks are formed when rock changes over a period of time due to a lot of physical changes like pressure, heat and different chemical activity. When sedimentary rocks or igneous rocks go through the physical process such as pressure exposure, heat changes, and tectonic plate movement at plate edges. This rock changes occur when these rocks are exposed to an environment.
This type of rock has been classified into two main categories although there are hundreds of different types and the most abundant ones are again classified into types- foliated and unfoliated rocks. Metamorphic rocks are classified into different classes which are arranged according to their complexity of chemical molecules.
- ultramafic rocks
- carbonate rocks
- Pelites or shale
- Mafic rocks
- Feldspathic rocks
Learn more about igneous rocks here.
Characteristics of Metamorphic Rock
- Cataclastic metamorphism occurs along with the tectonic plate faults where the rocks get rubbed with each other which results in the grain size reduction.
- Transformation of these rocks are classified as one which could not form non foliated rock and is of low grade.
- Circulation of rock results in huge number of mineral water chemical reactions which results in different kinds of precious metals and stones.