EE WAS REPLACING A BROKEN PIN IN THE DYNA-TRAC AT THE F-8 LONGWALL SECTION TAILGATE WHEN A PIECEOF ROCK FELL FROM BETWEEN #189 AND #190 SHEILDS AND STRUCK HIM ON THE RIGHT FOREARM CAUSING 3 LACERATIONS REQUIRING 20 SUTURES , THE ROCK MEASURED 8"" THICK, 6"" WIDE AND 36"" IN LENGTH.