EE WAS ON HIS KNEES PUMPING OIL INTO THE ROOF BOLTER. A PIECE OF ROCK MEASURING APPROX 18"" X 8' X 0-2"" THICK FELL FROM THE MINE ROOF STRIKING HIM IN HIS RIGHT LEG. EE ALSO STATED HIS LEFT KNEE WAS EXPERIENCING SOME DISCOMFORT. MINING HEIGHT WAS APPROX 8 FT HIGH.