HE & CO-WORKERS WERE SETTING BREAKER POSTS BETWEEN #4 & #5 ENTRIES AT #34 CROSSCUT ON THE 8 LEFT PANEL (005) SECTION. HE WAS ON HIS LEFT KNEE AND CLEANING OUT A SPOT TO PLACE A TIMBER WHEN A PIECE OF ROCK APPROX. 33""X 35""X 2""THICK FELL FROM BETWEEN BOLTS AND STRUCK HIM ON THE LEFT LEG, ABOVE THE ANKLE.