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Gneiss

Banded iron formation
Banded iron formation



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Banded iron formation

Formation of Gneiss and Banded iron formation

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.
The banded iron layers are formed in sea water when oxygen is released by photosynthetic cyano-bacteria. The oxygen then combines with dissolved iron in ocean to form insoluble iron oxides, which precipitated out, forming a thin layer of banded iron formation on ocean floor.
1.2 Composition
1.2.1 Mineral Content
Biotite, Chlorite, Feldspar, Garnet, Graphite, Hornblade, Micas, Muscovite or Illite, Quartz, Quartzite, Silica, Zircon
Hematite, Magnetite, Quartz
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
Fe, Iron(III) Oxide, Silicon Dioxide
1.3 Transformation
1.3.1 Metamorphism
50% Metamorphic Rocks Rocks have it !
19% Sedimentary Rocks Rocks have it !
1.3.2 Types of Metamorphism
Impact Metamorphism
Not Applicable
1.3.3 Weathering
65% Metamorphic Rocks Rocks have it !
78% Sedimentary Rocks Rocks have it !
1.3.4 Types of Weathering
Biological Weathering, Mechanical Weathering
Chemical Weathering
1.3.5 Erosion
77% Metamorphic Rocks Rocks have it !
86% Sedimentary Rocks Rocks have it !
1.3.6 Types of Erosion
Chemical Erosion, Coastal Erosion, Sea Erosion
Coastal Erosion, Wind Erosion

Gneiss and Banded iron formation Formation

Formation of rocks is a long process and hence, Gneiss and Banded iron formation 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 Banded iron formation, composition of Gneiss and Banded iron formation and their transformation.