An apparatus and method for comminution of ore material includes a radio frequency multi-input, multimode processing resonant cavity arranged for radio frequency electromagnetic irradiation of a stream of ore material passing therethrough. A multi-input measurement resonant cavity, located upstream of the processing resonant cavity may be provided to determine an impedance of ore material to be irradiated in the processing resonant cavity. The radio frequency electrical field generated in the processing resonant cavity is matched to the determined impedance.