While replacing flashing on a tail pulley discharge belt on the surge bin Unit #17-14, co-worker was using a 12lb sledge hammer to punch holes with an awl/punch. He swung the hammer, the head came down and hit the top of the awl-slipped off the awl and hit EE's hand, EE was holding the awl in place. EE was driven by the quarry foreman to the ER in West Union for xrays.