EE WAS INSTALLING THE OUTSIDE BOLT IN THE LAST ROW OF BOLTS. AT THIS TIME A PIECE OF ROCK FELL, HITTING THE CANOPY, SLIDING FROM OFF THE CANOPY.HITTING EE IN THE RIGHT SHOULDER AND NECK. THE ROOF BOLTER WAS EQUIPPED WITH MASSEY ENERGY ""IRONING BOARD"" FLAPS. THE ROCK MEASURED 2' BY 2' BY 3"".