EE WAS OPENING A SET OF AIR-LOCK EQUIPMENT DOORS LOCATED AT #24 CROSSCUT ALONG THE MAIN EAST HAULAGE ROADWAY. HE WAS STANDING AGAINST THE NORTH RIB WHEN A PIECE OF ROCK 10"" X 10"" X 4"" THICK FE LL OUR FROM BETWEEN THE RIB AND PERMANENT ROOF SUPPORTS. THE ROCK STRUCK HIM ON THE HEAD AND NE CK CAUSING SPRAIN/STRAIN INJURY TO HIS CERVICLE SPINE.