Shatter cones produced experimentally by impacts in limestone targets

Experimentally produced impact craters in limestone targets displayed millimeter-sized shatter cones within crater spallation zones. The craters have been produced by accelerating spherical metal projectiles by means of a light-gas gun. Variation of the impact velocity showed that at about 3 km/s shatter cone formation starts and is reproducible at any higher impact velocities. In most cases the cone apices were pointing in the direction of the impact center. The occurrence of shatter cones directly at the target surface (spallation zones of craters) does not support a theoretical model on shatter cone formation published by Gash (1971).