THE EE WAS ROOF BOLTING IN THE FACE. WHILE INSTALLING THE OUTSIDE BOLT ON HIS SIDE A PIECE OF ROCK 3' X 2' X 4"" IN THICKNESS FELL FROM BETWEENTHE BOLT BEING INSTALLED & THE RIB. THE ROCK STRUCK THE CANOPY OF THE BOLTER, BROKE INTO SEVERAL PIECES THEN STRUCK THE EE ON THE RIGHT LEG NEAR THE KNEE