EE WAS ROOF BOLTING AND A PIECE OF ROCK FELL FROM THE ROOF, STRUCK DRILL HEAD BOUNCED OVER HITTING EE ON TOP OF HEAD. CAUSE OF INJURY WAS AWANESS AND NOT PULLING DOWN LOOSE TOP. COMPLIANCE WIT H RULES REGS WAS A FACTOR, PERSONNEL EQUIPMENT NOT A FACTOR, MINE PROFICIENCY A FACTOR, MINING EQUP/SYSTEMS NOT A FACTOR.