EE WAS WALKING IN THE #5 ENTRY WHEN A PIECE OF DRAW ROCK (LAMINATED SANDSTONE) MEASURING 23"" X 14"" X 4"" THICK FELL & STRUCK HIM ON THE HARD HAT& RIGHT SHOULDER. THE HEIGHT WAS 99"". HE SUFFERE D A SLIGHT CONCUSSION & MUSCLE STRAIN TO THE LOWER BACK. HE WAS UNABLE TO WORK ON HIS NEXT REGULARLY SCHEDULED SHIFT.