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Coesite is a form (polymorph
Polymorphism (materials science)

Polymorphism in materials science is the ability of a solid material to exist in more than one form or crystal structure. Polymorphism can potentially be found in any crystalline material including polymers, minerals, and metals, and is related to allotropy, which refers to chemical elements....
) of silicon dioxide
Silicon dioxide

The chemical compound 'silicon dioxide', also known as 'silica' , is an oxide of silicon with a chemical formula of and has been known for its hardness since antiquity....
 Si
Silicon

Silicon is the most common metalloid. It is a chemical element, which has the symbol Si and atomic number 14. The atomic mass is 28.0855....
O
Oxygen

Oxygen no O2 produced; 2) O2 produced, but absorbed in oceans & seabed rock; 3) O2 starts to gas out of the oceans, but is absorbed by land surfaces and formation of ozone layer; 4-5) O2 sinks filled and the gas accumulates]]...
2 that is formed when very high pressure (2–3 gigapascals) and moderately high temperature (700 °C) are applied to quartz
Quartz

Quartz is the most abundant mineral in the Earth's continental crust . It is made up of a Crystal structure of silica tetrahedra. Quartz has a hardness of 7 on the Mohs scale and a density of 2.65 g/cm?....
. Coesite was first created by Loring Coes, Jr. in 1953. In 1960, coesite was found by Edward C. T. Chao
Edward C. T. Chao

Edward C. T. Chao was one of the founders of the field of impact crater metamorphism, the study of the effects of meteorite impacts on the Earth's crust....
, in collaboration with Eugene Shoemaker, to naturally occur in the Barringer Crater, which was evidence that the crater must have been formed by an impact.

The presence of coesite in unmetamorphosed rocks may be evidence of a meteorite impact event
Impact event

An impact event is the collision of a large meteoroid, asteroid or comet with the Earth. Impact events have been a plot and background element in science fiction since knowledge of real impacts became established in the scientific mainstream....
 or of an atomic bomb explosion.






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Coesite is a form (polymorph
Polymorphism (materials science)

Polymorphism in materials science is the ability of a solid material to exist in more than one form or crystal structure. Polymorphism can potentially be found in any crystalline material including polymers, minerals, and metals, and is related to allotropy, which refers to chemical elements....
) of silicon dioxide
Silicon dioxide

The chemical compound 'silicon dioxide', also known as 'silica' , is an oxide of silicon with a chemical formula of and has been known for its hardness since antiquity....
 Si
Silicon

Silicon is the most common metalloid. It is a chemical element, which has the symbol Si and atomic number 14. The atomic mass is 28.0855....
O
Oxygen

Oxygen no O2 produced; 2) O2 produced, but absorbed in oceans & seabed rock; 3) O2 starts to gas out of the oceans, but is absorbed by land surfaces and formation of ozone layer; 4-5) O2 sinks filled and the gas accumulates]]...
2 that is formed when very high pressure (2–3 gigapascals) and moderately high temperature (700 °C) are applied to quartz
Quartz

Quartz is the most abundant mineral in the Earth's continental crust . It is made up of a Crystal structure of silica tetrahedra. Quartz has a hardness of 7 on the Mohs scale and a density of 2.65 g/cm?....
. Coesite was first created by Loring Coes, Jr. in 1953. In 1960, coesite was found by Edward C. T. Chao
Edward C. T. Chao

Edward C. T. Chao was one of the founders of the field of impact crater metamorphism, the study of the effects of meteorite impacts on the Earth's crust....
, in collaboration with Eugene Shoemaker, to naturally occur in the Barringer Crater, which was evidence that the crater must have been formed by an impact.

The presence of coesite in unmetamorphosed rocks may be evidence of a meteorite impact event
Impact event

An impact event is the collision of a large meteoroid, asteroid or comet with the Earth. Impact events have been a plot and background element in science fiction since knowledge of real impacts became established in the scientific mainstream....
 or of an atomic bomb explosion. In metamorphic rocks, coesite commonly is one of the best mineral indicators of metamorphism at very high pressures (UHP, or ultrahigh-pressure metamorphism). Such UHP metamorphic rocks record subduction or continental collisions in which crustal rocks are carried to depths of 70 km or more. Coesite also has been identified in eclogite
Eclogite

Eclogite is a coarse-grained mafic metamorphic rock. Eclogite is of special interest for at least two reasons. First, it forms at pressures greater than those typical of the Crust of the Earth....
 xenoliths from the mantle of the earth that were carried up by ascending magmas; kimberlite
Kimberlite

Kimberlite is a type of potassic volcanic rock best known for sometimes containing diamonds. It is named after the town of Kimberley, Northern Cape in South Africa, where the discovery of an diamond in 1871 spawned a diamond rush, eventually creating the Big Hole....
 is the most common host of such xenoliths.

The molecular structure of coesite consists of four silicon dioxide tetrahedra
Tetrahedron

A tetrahedron is a polyhedron composed of four triangle faces, three of which meet at each vertex . A regular tetrahedron is one in which the four triangles are regular, or "equilateral", and is one of the Platonic solids....
 arranged in a ring. The rings are further arranged into a chain. This structure is metastable within the stability field of quartz: coesite will eventually decay back into quartz with a consequent volume increase, although the metamorphic reaction
Metamorphic reaction

A metamorphic reaction is a chemical reaction that takes place during the geological process of metamorphism in an amalgamate of minerals that helps determine the final stable state of the resulting metamorphic rock....
 is very slow at the low temperatures of the Earth's surface.

See also

  • List of minerals
    List of minerals

    This is a List of minerals for which there are Wikipedia articles. Mineral variety names and mineraloids are to be listed after the valid minerals for each letter....
  • List of minerals named after people
    List of minerals named after people

    This is a list of minerals named after people. The chemical composition follows name when available.Sorted by name:...
  • Stishovite
    Stishovite

    Stishovite is an extremely hard, dense tetragonal form of silicon dioxide. It was traditionally considered the hardest known oxide; however, boron suboxide was recently discovered to be much harder....
    , a related mineral


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