MINER WAS CLEANING UP ROCKS THAT HAD FALLED OFF THE MOVING FEED CONVEYOR. HE SAID HE TOSSED A COUPLE OF THEM BACK ONTO THE FEED CONVEYOR AND WAS IN THE PROCESS OF PICKING UP ANOTHER ROCK WHEN HE WAS HIT IN THE BACK BY A ROCK THAT ROLLED OFF THE CONVEYOR BELT. THIS KNOCKED HIM TO THE GROUND, WHERE CO-WORKERS FOUND HIM.