Shocked quartz is a state of quartz altered by extreme high pressure. In the 1940s, American scientists discovered it while conducting underground atomic bomb testing. Shocked quartz is found in impact craters caused by meteorites and nuclear bomb explosions. The atoms of quartz are shifted after such a blast occurs.
The difference between shocked quartz and normal quartz can only be noticed underneath a petrographic microscope. A petrographic microscope is designed to study quartz with the aid of polarized light. Sets of microscopic parallel lines criss-cross each other on the face of the quartz. These lines, when viewed from edge on, are referred to as shock lamellae.