EMPLOYEE WAS OPERATING THE ROOF BOLTER. AS HE WAS SWINGING THE HEAD OF THE BOLTER TO SET OUTSIDEBOLT IN LAST ROW OF BOLTS A BLOW THAT HAD BEEN LEFT (APPROX. 1'W X 5'L X 12"") FELL & STRUCK HIM ON THE RIGHT FOOT. THIS RESULTED IN A CONTUSION OF THE LEG AND FOOT. HE STARTED MISSING WORK ON 7/13/00.