EMPLOYEE WAS IN THE PROCESS OF REMOVING A ROCK STUCK IN THE INCLINE BELT ON THE REAR OF THE HIGHWALL MINER LAUNCH, THE REAR OF THE LAUNCH WAS RAISED OFF THE STACKER BELT ABOUT 6 FT WHILE STAND ING ON STACKER BELT BELT TAILPIECE TRYING TO FREE ROCK, ROCK FELL ON HIM ACROSS UPPER CHEST AND SHOULDERS.