IE and co-worker were tying in a round in MWD 4163. Working their way right to left, IE was past the cut tying in the last 3 holes when a chunk of ore from between 2 slips fell striking IE and the handrail. Mine Rescue was dispatched and brought IE to surface for the Ambulance. IE suffered a mild concussion, 3 staples in their head and a bruised hip.