Stone..

[Undefined]

mining cave walls for stones kind of sucks but that's the price you pay for living in a stone-less area, I'm getting plenty with 18 str and a Q10 axe.
Once you start smelting ore you'll get stones for anything that isn't a bar and when you start digging basements I assume it'll produce boulders. It's a pure early game issue that you can avoid just by settling somewhere that has overground stones.