The synthesis of stishovite and its subsequent discovery in naturally shocked rocks in Meteor Crater, Arizona and the Ries Crater, Germany, has revolutionised the study of shock metamorphism and impact cratering by providing an index mineral, in addition to coesite, that can be used as proof of shock metamorphism . Synthesis of stishovite also ignited considerable interest the existence and stabilities of other dense polymorphs with octahedrally coordinated silicon. SiO 2 polymorphs that are more dense than stishovite are important in determining the stability of perovskite in the Earth's lower mantle. Additional constrains on shock pressures in meteorites are important to unravel the impact records of asteroids and planets in the early history of the solar system. BSE-mode SEM images of SiO 2 and maskelynite.
Shergotty meteorite is heavily shocked.
Maskelynite appears to have been quenched from a shock-induced melt. These cracks are similar to those formed around coesite in high pressure metamorphic rocks and indicate that the volume of the silica phase increased greatly with decompression. The present results confirm the existence of such a structure in a natural sample.