Formation of Gneiss and Coquina

Gneiss

Coquina

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1 Formation

1.1 Formation

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.

Coquina is a sedimentary rock which is formed when billions of small clam-like seashell, called Coquina, or cockleshell are die and hence are deposited, buried and turns into a rock when pressure is applied.

1.2 Composition

1.2.1 Mineral Content

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

Apatite, Augite, Bronzite, Calcite, Chert, Chlorite, Clay Minerals, Epidote, Feldspar, Garnet, Micas, Muscovite or Illite

1.2.2 Compound Content

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

CaO, Carbon Dioxide, Iron(III) Oxide, MgO

1.3 Transformation

1.3.1 Metamorphism

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50% Metamorphic Rocks Rocks have it !

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19% Sedimentary Rocks Rocks have it !

1.3.2 Types of Metamorphism

Impact Metamorphism

Not Applicable

1.3.3 Weathering

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65% Metamorphic Rocks Rocks have it !

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78% Sedimentary Rocks Rocks have it !

1.3.4 Types of Weathering

Biological Weathering, Mechanical Weathering

Biological Weathering, Chemical Weathering, Mechanical Weathering

1.3.5 Erosion

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77% Metamorphic Rocks Rocks have it !

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86% Sedimentary Rocks Rocks have it !

1.3.6 Types of Erosion

Chemical Erosion, Coastal Erosion, Sea Erosion

Coastal Erosion, Sea Erosion, Water Erosion, Wind Erosion

Gneiss and Coquina Formation

Formation of rocks is a long process and hence, Gneiss and Coquina 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 Gneiss and Coquina, composition of Gneiss and Coquina and their transformation.