WE WERE IN AN AREA THAT HAD BEEN BOLTED DISCUSSING A BOLTING PLAN. WE WERE STANDING IN FRONT OF BOLTING MACHINE WITH 4 OTHER EMPLOYEES. A PIECE OF ROCK FELL FROM BETWEEN THE BOLTS 36"" X 36"" X 1"" THICK & STRUCK ME ON THE HARD HAT, FACE & EAR. THIS INJURY DID NOT INVOLVE ANY ASPECT OF COMPLIANCE WITH RULES OR REGULATIONS, JOB SKILLS, ATTITUDE OR PROTECTIVE ITEMS.