HE & A CO-WORKER WERE ROOFBOLTING THE TURN CUT IN THE RIGHT CROSSCUT OF #7 ENTRY. WHILE WAITING ON HIS BUDDY HE DECIDED TO CLEAN HIS DUST BOX. HE WAS STOOPED OVER BESIDE THE DRILL WHEN A PIECE OF ROCK APPROX. 9' LONG X 21"" WIDE X 15"" THICK FELL FROM THE RIB NEAR THE TOP OF THE SEAM & STRUCK HIM IN THE BACK.