Upon an investigation the EE was pulling a supply car into the mine using a diesel tractor when a piece of rock fell and hit him. The rock fell from the edge of a half header which was hanging on the roof of the mine. The rock was approx 14"" x 17"" x 2"" & struck EE in the head. The mine roof was about 6 1/2 ft. in height. EE was transported via ambulance to Boone Memorial Hospital.