Minecraft wiki entry for Tips_and_tricks, associated text: Once you reach a dead end, you can go back and mine the various ores that you've passed. Leave the torches that you placed, to keep the area lit and prevent monsters from spawning. Then you can go down another branch of the cave, and repeat the above process until the cave is done. If you hear monsters but can't see a path to them, you may be near another cave or ravine -- if you have a sword and perhaps some armor, try digging a tunnel in the direction the sounds are coming from... but be prepared for a fight, or a hasty retreat!