; There is no space to mine here. Clear the area first. : Occurs when the tile you're standing on has 100 items on. Move a few objects and you can continue.
; You fail to produce anything here. The rock is stone hard. : Occurs on the surface. This means the tile you are attempting to excavate is actually an ore vein. There's nothing to do about it, you simply have to make your entrance on another tile. Note that if you make the entrance one tile below the vein, the tunnel will open right into the vein and cannot be extended until the vein is depleted. The best course of action at this point would probably be to mine out a rock tile next to the one you get this message on.
: Happens when mining down a floor and roof is too high, Can only be fixed by collapsing all surround affected tiles and remining.(aka. if you want the tile flat collapse it and remine, if you want to lower it collapse all surrounding tiles and remine.)
; You hear falling rocks from the other side of the wall. A deep shaft will probably emerge. : Occurs inside a mine. Caused when there is already another mine nearby, but there is too much of a height difference to connect the two mines.
; You cannot keep mining here. The rock is unusually hard. : The message displayed when one attempts to open a tunnel directly onto a vein.