EQUIPMENT CORE DRILL PERSONS WORKING ON DRILL. WHILE DISCONNECTING DRILL RODS WAS STRUCK BY A CRESENT WRENCH THAT WAS LEFT SITTING IN A BAD POSITION ON MACHINE. EE PULLED DOWN PN WRENCH TO UNSCREW NEW ROD. WRENCH HE PULLED DOWN ON HITTHE CRESENT WRENCH THAT WAS SITTING ON MACHINE CAUSING WRENCH TO FLY UP AND STRIKE EE ON THE RT. SIDE OF HEAD, IN EYE AREA.