EE was drilling a bolt hole for the 3rd bolt in the 1st row of a cut just taken out in the no. 2 heading. After drilling approx. 8 - 10"" into the roof the drill steel hit a crack in the roof. The rock infront if him started to work and he started to run back to the back of the machine. A slick ensided slip fell from the roof. A piece of this rock hit the side of his foot.