On rock tiles you can [[Prospecting|prospect]] for ore, create [[mining|cave entrances]], and terraform it.
Rock tile terraforming with a pickaxe works in the same way as [[digging]] dirt. Stand on the corner you want to ''lower'', activate a pickaxe, right-click a rock tile, and select ''Mining''(Note: All surrounding tiles must also be rock). Every few actions you ''lower'' the corner by 1 dirt.
You can not raise a rock tile, but you can raise the corner by dropping [[Pile of dirt|dirt]] or [[heap of sand|sand]] on it.