Okay, this is really annoying. I've been trying to get stone to carve things out of, but I never get large enough pieces. I've mined out several rooms, and I get plenty of pebbles and stones, but no large rocks or boulders. Are there any tricks to improve my rock sizes? Shovel or pickaxe?

Unless you have very little foraging, I'd suggest just trying another area then. Also lead with a prospect careful, this helps a ton.

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It is impossible to strive for the heroic life. The title of hero is bestowed by the survivors upon the fallen, who themselves know nothing of heroism.
-Johan Huizinga