Mineshaft

Mineshafts are generated structures found primarily in caves. They consist of interlinked 3x3 tunnels with incomplete rail lines running through them with oak wood platforms bridging gaps or hanging in larger exposed caverns. Mineshafts are the only structures where cave spider monster spawners can be found.

A unique variant of mineshaft made out of dark oak wood can generate on the surface in badlands biomes.

Generation
Mineshafts generate in any Overworld biome, usually underground or rarely in oceans. They are generated before chunk features such as ores. Multiple mineshafts can generate near each other, producing larger complexes. As mineshafts intersect with caves and canyons, corridors generate a bridge of planks suspended under chains over empty space. When a mineshaft intersects with an aquifer, a barrier of solid blocks generates to prevent fluids from flowing into the mineshaft, often resulting in corridors cut off from the rest of the mineshaft.

Mineshafts often generate on the surface in badlands biomes. Badlands mineshafts are composed of dark oak planks and fences with railways more complete above ground. Since badlands biomes generate gold ore often and at higher altitudes, they are good places to easily find gold.

Structure


All mineshafts have:
 * Starting point: a 10×10 parlor, with an arched ceiling and one to four exits in each direction.
 * Corridors: some 3×3 tunnels and junctions are supported by planks and fences. Some places are decorated with torches and cobwebs. On long corridors, these supports are placed four blocks away from each other, while some have missing planks which may be filled up with cobwebs or blocks of stone jutting out from the top. The tunnels are connected by incomplete rail systems on the ground, upon which minecarts with chests generate uncommonly. Cobwebs do not generate if they would not be connected to solid blocks, while corridors generate with log pillars, chains and fences for support if they are in mid-air.
 * Crossings: dual-floor, 5×5 intersections supported by wooden columns.
 * Staircases: diagonal tunnels, stairs blocks are not used.
 * Abandoned passageways: accessory corridors with cobwebs concealing cave spider monster spawners.

Trivia

 * The central room of a mineshaft never generates in the same chunk as (0, 0) in any Minecraft world.
 * Any "chest" in a mineshaft becomes a minecart with chest that rests on top of some rails.

Publicity

 * In LEGO Minecraft Micro World – "The Village", a mineshaft is beneath a village.