Abandoned Mineshafts are underground structures added by vanilla Minecraft. They consist of tunnels supported by wooden beams and often intersect with ravines and caves. Abandoned Mineshafts are full of worn-down minecart tracks and the occasional minecart or chest. These chests contain regular dungeon loot. Mineshafts are useful for finding large amounts of rails and ores. If a mineshaft happens to intersect with a deep ravine or a hole, a wooden bridge will span the gap. Mineshafts are the only structures added by vanilla Minecraft that house cave spiders, which spawn from spawners surrounded by cobwebs.