EMPLOYEE WAS STANDING IN PANLINE TO ASSIST ANOTHER EMPLOYEE USING A COBRA DRILL TO INSTALL A ROOF BOLT BETWEEN SHIELD TIP AND LONGWALL FACE AT #183 SHIELD E-8 LONGWALL SECTION. AS THEY BEGAN D RILLING, THE MINE ROOF BROKE AND A PIECE OF ROCK FELL AND GLANCED OFF THE SHEARER COWL AND STRUCK EMPLOYEE ON TOP OF THE LEFT FOOT RESULTING IN A FRACTURE TO HIS BIG TOE.