Formation of Schist and Gneiss

Schist

Gneiss

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1 Formation

1.1 Formation

Schist formed by dynamic metamorphism at high temperatures and pressures that aligns the grains of mica, hornblende and other elongated minerals into thin layers.

Gneiss is a high grade metamorphic rock i.e. it has been subjected to higher temperatures and pressures than schist. It is formed by the metamorphosis of Gneiss forms from volcanic rock, shale or granitie.

1.2 Composition

1.2.1 Mineral Content

Alusite, Amphibole, Biotite, Chlorite, Epidote, Feldspar, Garnet, Graphite, Hornblade, Kyanite, Micas, Muscovite or Illite, Porphyroblasts, Quartz, Sillimanite, Staurolite, Talc

Biotite, Chlorite, Feldspar, Garnet, Graphite, Hornblade, Micas, Muscovite or Illite, Quartz, Quartzite, Silica, Zircon

1.2.2 Compound Content

CaO, Carbon Dioxide, MgO

Aluminium Oxide, NaCl, CaO, Iron(III) Oxide, FeO, Potassium Oxide, Magnesium Carbonate, MgO, MnO, Phosphorus Pentoxide, Silicon Dioxide, Titanium Dioxide

1.3 Transformation

1.3.1 Metamorphism

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50% Metamorphic Rocks Rocks have it !

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50% Metamorphic Rocks Rocks have it !

1.3.2 Types of Metamorphism

Not Applicable

Impact Metamorphism

1.3.3 Weathering

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65% Metamorphic Rocks Rocks have it !

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65% Metamorphic Rocks Rocks have it !

1.3.4 Types of Weathering

Biological Weathering, Chemical Weathering, Mechanical Weathering

Biological Weathering, Mechanical Weathering

1.3.5 Erosion

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77% Metamorphic Rocks Rocks have it !

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77% Metamorphic Rocks Rocks have it !

1.3.6 Types of Erosion

Chemical Erosion, Coastal Erosion, Glacier Erosion

Chemical Erosion, Coastal Erosion, Sea Erosion

Schist and Gneiss Formation

Formation of rocks is a long process and hence, Schist and Gneiss formation sounds very interesting. According to the formation, all rocks are divided into :Igneous Rocks, Fossil Rocks and Metamorphic Rocks. Igneous rocks form by crystallization of magma or lava. The magma is made up of various components of pre-existing rocks which have been subjected to melting either at subduction zones or within the Earth's mantle. Igneous rocks are generally seen at mid ocean ridges or in intra-plate hotspots. Sedimentary rocks are formed when sediments accumulate gradually. As the sediments are buried they get compacted as more and more material is deposited on top. Eventually the sediments become so dense that they form a rock. Metamorphic rocks are rocks which once existed as igneous or sedimentary rocks but have been subjected to varying degrees of pressure and heat within the Earth's crust. Get to know all about formation of Schist and Gneiss, composition of Schist and Gneiss and their transformation.