3 EAST MAINS EE WAS STANDING ABOUT MID MACHINE, IN 7 RT. BREAK BOLTING TOP PUTTING A CONNECTOR INTO DRILL STEEL WHEN A PIECE OF ROCK FELL OUT FROM BETWEEN BOLTS IN SUPPORTED ROOF AND STRUCK HI M ON THE LEFT SIDE OF HIS HARD HAT. THIS INCIDENT IS BEING INVESTIGATION AS TO IT REPORT ABILITY UNDER PART50. EE STARTED MISSING ON 8-9-02.