INJURED PARTY WAS ROOF BOLTING IN THE #3 ENTRY WHEN A PIECE OF ROCK FELL OUT OF THE MINE ROOF STRIKING HIM ON TOP OF HIS RT. ANKLE, BREAKING HIS LEG. HE WAS UNDER THE CANOPY ON THE ROOF BOLTER BUT HIS LEG WAS JUST A LITTLE BIT OUT FROM UNDER THE CANOPY WHEN THE ROCK FELL. THE ROCK WAS ABOUT 3""THICK, 1 & 1/2'LONG & 1 & 1/2'WIDE.