User:Anomie x/mine layout

This is my take on branch mining. It's based around 36-block-long "sections" with two layers of tunnels at Y=11 (foot level) and Y=7.

Supplies

 * General supplies
 * 1 minecart
 * 2 buckets of water
 * 1-2 shovels (stone is fine) if you want to deal with dirt and gravel faster
 * 64 extra torches, Just In Case
 * Food (steak is a good choice)
 * 64 "marker blocks": something that doesn't naturally occur underground, e.g. stained clay, sandstone, or even furnaces or redstone blocks. Wool or wood could work too, but note they will burn if lava is nearby.
 * 1 chest (usually left at the end of the tunnel)
 * 1 crafting table (usually left at the end of the tunnel)
 * 1 diamond pickaxe with Fortune III (Unbreaking is good too)


 * Per-section
 * 1 powered rail
 * 35 rail
 * 6 Jack o'Lantern
 * 72 torches
 * 12 ladders
 * 2 chests
 * 1 diamond pickaxes with Unbreaking III and a high level Efficiency
 * Possibly bring a second if the first is getting low, or be prepared with an anvil to repair it.

Layout
The main tunnel is at Y=11. It's 3 blocks high, with 1 block dug out of either side to mark where the branches will be. Chests are placed in the walls to hold all the cobblestone, gravel, and dirt from the mine, and ladders are placed at intervals to reach the lower tunnel. A crafting table is placed at the end for crafting redstone, coal, lapis lazuli, and (if you're lucky enough to get more than 64)  diamond into resource blocks; a chest is placed on top of the table to hold the ores while mining out the section (in case of death). An infinite water source is dug into the floor for refilling buckets, if necessary. Jack o'Lanterns are placed in the wall at foot level for light.

Dig out any ores or gravel in the floor, replacing with cobblestone. Otherwise you're likely to break the rail later.

Note if you dig 2-high to mark the side branches, some will be at light level 7 which could allow mobs to spawn.

The lower level at Y=7 is much like the main tunnel, but is only 2 blocks high and has no rails. The branch tunnels are offset.

Then dig the side branches. Each branch is 2-high and 26 blocks long, with a torch at foot level at the 7th block and 20th block. Feel free to dig the branches longer if you'd like, just make them a multiple of 13 blocks long with torches every 7+13x blocks (i.e. the 33rd, 46th, and so on). If using F3, the torches after the first will go on blocks that show light level 0 at head level (1 at foot level in 1.8) and the end of the tunnel will show light level 7 at head level (8 at foot level in 1.8).

General tips and trivia

 * One unenchanted diamond pick isn't enough for a full section. An Unbreaking III diamond pick should last about 3, although in practice it won't unless you ignore most ores.
 * Don't let your inventory fill up so you can't pick up the stuff you mine, that's what the chests in the sides of the tunnel are for.
 * This method of mining is generally very safe if you do the lighting right and be careful of lava. Keep your armor on, but you might leave your weapons in the chest at the end of the tunnel so as to be able to carry more blocks. The same goes for clocks, compasses, minecarts, and other stuff you usually carry that doesn't have use down in the mine.
 * If you find a cave and don't want to explore it immediately (or at all), wall off the tunnel while including at least one of the "marker blocks" in the wall (and throw a torch on the marker block for good measure).
 * If you do want to go caving, it's probably a good idea to stash any ores and other valuables you're carrying and to retrieve your weapons if necessary.
 * When digging the main tunnel, you'll have to venture into the cave far enough to secure the area around the railway itself. I also find it handy to place 1-high cobblestone next to the rail where the stone walls would be, otherwise I tend to lose count of where the branches go.
 * Do not stand right up against the wall while digging or you're liable to get surprised by lava; if you stand a few blocks back you'll have enough time to retreat or switch to a bucket. This is especially important on the lower level.
 * When mining at Y=11, the lava will likely be at floor level.
 * For the main tunnel you'll have to bridge it (drenching with water works well) to be able to continue the railway. Be sure to add torches if there isn't enough lava left to light things up sufficiently.
 * For branches, drenching also works well; I'll often make a 1-wide bridge so the surrounding lava continues to light up the vicinity.
 * When mining at Y=7, the lava will likely be coming from above. It's generally easiest to just end the tunnel. For the main tunnel, pick it up again from the next ladder down the line.
 * If under Extreme Hills, be ready with a diamond sword in case you find silverfish.
 * It may be best to save iron ore until you have 80, which can be smelted with 1 coal block. The 9 coal that make up the coal block would only smelt 72 ores.
 * Silk Touch is pointless for mining unless you're planning to decorate with ore blocks. Crafting coal blocks, redstone blocks, and diamond blocks is more compact than storing ores even when using Fortune III, and lapis lazuli isn't common enough that it's worth worrying about the extra space taken by lapis lazuli blocks over ores. And you won't wear out both the Silk Touch pick and the Fortune pick.
 * For that matter, the Fortune pick probably shouldn't be wasted on coal (it's far too common, and a good tree farm gives unlimited easy charcoal) or redstone (both too common and Fortune doesn't have as much effect).
 * To avoid losing diamonds or other valuables to lava, dig around the vein first. This also allows finding diagonally-adjacent ore blocks that might otherwise be missed.
 * Despite its rarity, Fortune III has a huge effect on lapis lazuli, to the point where the mine might well produce more than iron.
 * The mine will produce more diamond than gold when using Fortune-enchanted picks. Worldwide, gold veins are about twice as common as diamond, but they're also spread across twice the volume giving them about the same density at Y=13 and below (which is where the mine is). Gold veins are also slightly larger, but even Fortune I more than makes up for it.