THE EMPLOYEE STATED THAT HE WAS INSTALLING A ROOF BOLT WHEN A ROCK FELL FROM THE MINE ROOF STRIKING THE CANOPY OF THE ROOF BOLT MACHINE AND BROKE INTO TWO PIECES. ONE PIECE OF ROCK FELL TO THE MINE FLOOR STRIKING THE EE ON THE RIGHT FOOT. THE ROCK MEASURED 17"" LONG 23"" WIDE AND 1-1/2"" THICK.