Coesite is a form of silicon dioxide that is formed when very high pressure (2–3 gigapascals) and moderately high temperature (700 °C) is applied to quartz. Coesite was first created by Loren Coes 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.
The presence of coesite is taken as evidence of an earth impact event or an atomic bomb explosion.
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: it will eventually decay back into quartz, although the reaction is very slow.
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