EE WAS ROOF BOLTING ON THE RIGHT SIDE OF THE MACHINE. THEY HAD JUST PUT THE STRAP INTO IT'S HOLDER & WERE PREPARING TO TRAM FORWARD TO THE NEXT ROW. EE WAS STANDING ABOUT MIDWAY ON THE BOLTER WHEN A ROCK 3.5' X 5' X 0-3"" THICK FELL FROM THE ROOF STRIKING HIS HARD HAT, KNOCKING HIM TO THE GROUND. HE CONTINUED TO WORK UNTIL 2/11/02 WHEN HE EXPERIENCED CHEST PAIN & NUMBNESS...