A rock fracturing technique, applied to secondary fragmentation in quarries, that is characterized by an almost instantaneous action and is accompanied by a mechanical weakening of the dielectric and a lowering of the resistance of the puncture path. If, after puncturing, a high-frequency current continues to pass between the contacts, the action 1057 of the conduction current and electric field will rapidly heat the rock, leading to thermal puncture, in which the dielectric is transformed into a good conductor along the puncture path. Further intensive heating will give rise to thermal stresses sufficient to fracture the rock.