THE EE WAS OPERATING THE RIGHT SIDE OF THE FLETCHER DUAL HEAD ROOF BOLTER. HE WAS BOLTING IN 7 RT. THE SECOND 20' CUT HAD BEEN TAKEN. HE HAD DRILLED THE FIRST HOLE OF THE SECOND ROW AND WAS RE MOVING THE STEEL WHEN A PIECE OF DRAW ROCK THAT WAS UNDETECTED FELL STRIKING HIM ON THE LEFT THUMB. THE ROCK WAS APPROX 23"" X 18"" X 8"" THICK.