Naturally occurring stishovite, SiO₂, is a mineral formed under very high pressure with the silicon atom in sixfold, or octahedral, coordination instead of the usual fourfold, or tetrahedral, coordination. It was discovered in the same type of Coconino sandstone from the Meteor Crater of Arizona. Stishovite has since been found in rocks from the Ries Crater of Germany. The presence of stishovite indicates formation pressures in excess of 10⁶ lb/in.² (7.5 gigapascals). The possibility of the existence of stishovite at great depths strongly influences the interpretations of geophysicists and solid-state physicists regarding the phase transitions of mineral matter, as well as the interpretation of seismic data in the study of such regions of the interior of the Earth.