Shocked quartz refers to quartz grains displaying microscopic defects in crystalline structure that were produced by the passage of high-velocity and high-pressure (>5 GPa) shock waves. Shock metamorphism is commonly illustrated in quartz by the presence of fine lamellae of amorphous SiO2 oriented parallel to two (or more) specific crystallographic planes and called planar deformation features, or PDF. Under extreme pressure, the whole quartz crystal transforms to glass. Shocked quartz is a diagnostic criterion to recognize hypervelocity impacts. Indeed, there are no other natural geological processes (tectonics, volcanism, etc.) capable of producing the required high-pressure dynamic shock waves. Shock features are common in impact crater rocks and in some meteorites. Shock metamorphism is also known in zircon, feldspar, and olivine.