Metamorphic rocks:
Igneous and sedimentary rocks undergo textural and mineralogical change due to high temperature and pressure without melting. These new rocks are called metamorphic rocks.
Metamorphism:
The process of producing metamorphic rocks is called metamorphism and its mean “new shape”
Anisotropy:
The property of a rock by virtue of it has different values of physical properties in different directions.
Classification of metamorphic rocks:
| Texture | Mineral content | Rock name | Original rock |
| Very fine grained salty texture | Minerals are too small to be seen | Slate | Shale or mud stone |
| Fine grained phyllitic texture(small wrinkle less) | Minerals are too small to be seen | Phyllite | Shale or mud stone |
| May appear very tiny visible grains | Minerals are too small to be seen | Green stone | Basalt |
| Medium to coarse grained schistone texture | Muscovite, biotite , chlorite, quartz, feldspar, pyroxene | Schist | Shale, mildstone, basalt |
| Coarse grained with pebbles from original rock | Muscovite, Chlorite, quartz, feldspar | Meta conglomerates | Conglomerates |
| Coarse grained with elongation and parallelism of grains | Muscovite, biotite, quartz, feldspar | Gneiss | Coarse grained igneous rock or clay and feldspar bearing sedimentary rocks |
| Fine to Coarse grained crystalline ganoblastic texture | Quartz , calcite, dolomite | Quartzite and marble | Sand stone (siliceous), Limestone, dolomite |
*quartz is much stronger rock as compared to schist.*schist is a very weak rock it can be easily broken.
Regional metamorphism: I n this type of metamorphism high stress condition takes place over a large scale.
Thermal or contact metamorphism: I n this type of metamorphism the changes occurred are only due to heat.whe thermal metamorphism occurs immediate near igneous intrusions it is called contact metamorphism.
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