EE WAS INSTALLING GROUND SUPPORT WITH A JACKLEG AND A FOUR FOOT STEEL. WHILE COLLARING THE HOLE, A 2'X3'X6"" ROCK CAME LOOSE. HE PUSHED THE MACHINE AWAY AS THE MACHINE BUCKLED. AS HE STEPPED BA CK FROM THE MACHINE, THE STEEL STRUCK HIS NOSE. DIAGNOSED WITH A FRACTURED NOSE.