MINER WAS CHECKING THE NO.1 BELTLINE. HE HAD WALKED NO.1 BELT FROM OUTSIDE TO THE TAIL PIECE AT BREAK #54. HE SAT DOWN TO REST & DRANK A DR.PEPPER. MINER SAID A ROCK FELL FROM THE ROOF & STRUC K HIS RT.KNEE CAP. MINER WALKED OUTSIDE & ASKED TO GO HOME. NO VISIBLE INJURY.