EE AND ANOTHER EE WERE ROOF BOLTING A FRESH CUT, HAD INSTALLED TWO FULL ROWS OF ROOF BOLTS AND WHILE DRILLING 1ST HOLE FOR 3RD ROW A ROCK FELL FROM TOP AND RIB AREA ABOUT 2 FT WIDE 3 FT LONG 0 TO 18"" THICK AND STRUCK EE ON RT SHOULDER X-RAY SHOWED BROKEN RT SHOULDER.