When you see rocks with lots of smooth holes in them you are very likely looking at limestone or dolomite, both of which will slowly dissolve in water, especially if the water has a pH below 7.0. That will increase the GH of the water. Just because the rocks are given dramatic or descriptive names does not mean they will not be dissolving in your water and raising the GH.
You can still use those rocks, but you will have to do regular big water changes to keep the GH down. If you change half the water every week, you limit the increase in GH to twice what the rocks are causing per week. So, if you gain 2 dGH in a week, doing weekly 50% water changes limits the total rise in GH to 4 dGH.