A method of breaking oversize stones left after quarry blasting. The balls weigh from 30 hundredweight (1,360 kg) to 2 st (1.8 t) (many use old cones from gyratory breakers) and are dropped from a crane on to the oversize stone. The drop height varies from about 20 to 33 ft (6.1 to 10.1 m). The method is economical and avoids secondary blasting.