Coesite is a form of silicon dioxide that is formed when very high pressure (2–3 gigapascals) and moderately high temperature (700 °C) are applied to quartz. Coesite was first created by Loring Coes, Jr. in 1953. In 1960, coesite was found by Eugene Shoemaker to naturally occur in the Barringer Crater, which was evidence that the crater must have been formed by an impact. R-phrases R42 R43 R49 S-phrases S22 S36 S37 S45 S53 Flash point non-flammable Supplementary data page Structure and properties n, εr, etc. ... The gigapascal, symbol GPa is an SI unit of pressure. ... Quartz is amongst one of the most common minerals in the Earths continental crust. ... 1953 (MCMLIII) was a common year starting on Thursday (link is to a full 1953 calendar). ... 1960 (MCMLX) was a leap year starting on Friday (the link is to a full 1960 calendar). ... Eugene Shoemaker at a stereoscopic microscope used for asteroid discovery Eugene Merle Shoemaker (or Gene Shoemaker) (April 28, 1928 – July 18, 1997) was one of the founders of the fields of planetary science and is best known for co-discovering the Comet Shoemaker-Levy 9 with his wife Carolyn Shoemaker... The Barringer Crater, also known as the Meteor Crater, is a famous impact crater created by a meteorite, located about 55 kilometers east of Flagstaff in the northern Arizona desert (USA). ...

The presence of coesite in unmetamorphosed rocks may be evidence of a meteorite impact event 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 xenoliths from the mantle of the earth that were carried up by ascending magmas; kimberlite is the most common host of such xenoliths. Artists impression of a major impact event. ... The mushroom cloud of the atomic bombing of Nagasaki, Japan, 1945, rose some 18 km (11 mi) above the epicenter. ...

The molecular structure of coesite consists of four silicon dioxide tetrahedra 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 reaction is very slow at the low temperatures of the Earth's surface. A tetrahedron (plural: tetrahedra) is a polyhedron composed of four triangular faces, three of which meet at each vertex. ... Metastability is the ability of a non-equilibrium state to persist for a long period of time. ...

External links

• Coesite page
• Barringer Meteor Crater science page