The invention provides a method and system for monitoring the flow of ore in block cave mining operations by inserting an active magnetic beacon 1 into an ore body 22 and generating an alternating magnetic signal with the beacon 1. The ore is monitored with a magnetometer (14, 15, 16, 17, 18) to detect the magnetic flux emitted by the beacon 1 thereby determining a position of the beacon. Successive recordings of the position of the magnetic beacon are taken as it moves along with the ore as it “caves”. In this way, flow patterns of the ore may be revealed.