Actually I just tried something. I went to the materials folder and copied the Rocks and Stones.mat then changed the extension to .brt and put it in the texture folder. Then I went into the texture area like you showed me above and found "Eroding Cliffs"(techno rock4) there. The only strange thing is that theres nothing but white blocks, you just have to click on each one and it then shows you a preview. Anyway I fixed my problem, thats a bunch!