EE WAS STRIKING A METAL PUNCH BAR WITH A 3 LB. HAMMER, ATTEMPTING TO REMOVE ROCK THAT WAS HUNG IN CONVEYOR BELT PULLEY. A PIECE OF METAL BAR BROKE OFF AND STRUCK EE IN THE LT. FOREARM CAUSING A PUNCTURE WOUND. SMALL PIECE OF METAL HAD TO BE REMOVED FROM HIS ARM. JUST HAVE TO KEEP ARM DRY & CLEAN.