I was able to drill 8 holes in hard basalt with this drill. We went a full 24 inches into the hole with the Hilti chuck, which allowed the universal stand that holds the solar panels to be anchored deeper. Caveat: We got stuck twice the first time for not vacuuming the trash for too long. out of the hole and it pooled on top of the chisel, interfering with its extraction. The stone fell about 14 inches into the hole and got stuck at the top of the bit flanges and the wall of the hole. We had to use a smaller hammer and chisel, break up the problematic stone, and remove the large chisel.