Minecraft wiki entry for Mining, associated text: A variation on this kind of tunnel-mining is to drill a finger tunnel into the stone for 20 blocks, placing torches as they go; retrieve any ore found; then recover the torches as players exit, plunging the tunnel back into darkness; then block up the entrance to the finger tunnel with just two blocks of surplus cobble. By leaving the finger tunnel unlit, and unfilled in, it's true that monsters may spawn later, but they are trapped in the walled-off tunnel. Be careful not to mine back into the same area later and also, there is a low chance that monstrous noise might become disconcerting later.