FINAL PUSH OUT HAD JUST BEEN COMPLETED IN NO.3 ENTRY & THE CONTINUOUS MINER BACKED OUT OF THE PLACE. INJURED & HIS SUPERVISOR WERE STANDING IN THE INTERSECTION IN THE LAST OPEN BREAK IN NO.3 ENTRY PREPARING TO MOVE THE MRS'S WHEN A PIECE OF ROCK (APPROX 34""X20""X 3""-7"" THICK) FELL FROM THE MINE ROOF FROM BETWEEN ROOF BOLTS STRIKING HIM ON HIS BACK AND LOWER RIGHT LEG.