TNT

TNT is a block used to cause explosions.

Explosion Properties


Upon being in the blast radius of a nearby explosion, struck with flint and steel, contact with fire, or the application of redstone current, TNT will follow the laws of physics (e.g., gravity), emit smoke, flash white, and explode after 4 seconds. Almost all blocks (see list below), mobs, and players caught in the blast radius will take damage or be destroyed outright. However, the damage to blocks (but not the player or mobs) can be prevented by detonating the TNT in a liquid.

The TNT blast will propagate according to this formula f=e-r, where f is the force of the TNT blast after propagating through the block, e is the energy of the blast before propagating through the block, and r is the blast resistance of the block. Thus, the explosion propagates farthest (7 blocks) through air, which has a blast resistance of zero. However, TNT immediately enclosed in stone will destroy an exact 3x3x3 cube originating from the center of the blast. It will kill you at close range. Numerous blocks and entities can survive TNT blasts, and even protect the player. In the case of blocks, Obsidian, Bedrock, and liquid source blocks are immune to TNT explosions, which allows for bomb shelters, a sealed world, and TNT cannons, respectively. In addition, a player or mob sitting in a minecart will take minimal damage from a TNT explosion, and this effect allows them to be launched great distances.

Unfortunately, the use of TNT is problematic. Instead of burning to ash, TNT activates (but still burns, allowing the fire to spread to other blocks such as TNT), thus making fire control systems near any quantity of TNT a must. For those who use TNT in the Nether, or deep underground, lava can and will eventually set fire to TNT, causing it to detonate. Furthermore, since TNT explosions require intensive physics calculations, large explosions will cause severe stuttering in singleplayer and extreme lag while playing in multiplayer.

In addition, TNT has several interesting properties. Theoretically, an infinite amount of primed TNT can fit into one cubic meter because primed TNT will not collide with other primed TNT. Sand and Gravel blocks will react accordingly to a detonation, scattering from the point of origin, and will fall through the TNT when it is triggered. If Sand or Gravel fall through primed TNT while it is underwater, the TNT will detonate normally, causing an explosion.

Uses
TNT monster traps can be created, making TNT a powerful defensive tool. When exposed to a Redstone current, the TNT activates as if it had been activated by a player. Combine this with a Pressure Plate and you can create an automatic defense for your buildings. This method is a one-off, as the TNT needs to be replaced after each use.

For the TNT to receive the circuit's signal, the Redstone needs to be directed straight into it from at least one of four sides, from either the Layer the TNT is based on, or above or below one layer. Diagonally adjacent entry will not make a connection. Redstone next to TNT will also set off the TNT, even if it is not directly connected with it (through a T connection not directly connected, or an "I" connection running parallel alongside it). TNT will only be set off by redstone if the redstone signal it is receiving turns on. This means that if it is receiving a current when it is placed, it will not be set off, but if the signal turns off and turns on again, it will be set off. There is however a bug where after flipping the signal off, sometimes only a few of the TNT blocks will become active. Redstone torches will activate a TNT block as well if directly under the TNT block, or under a block on which the TNT rests.

TNT is also good for clearing large amounts of dirt or gravel when mining underground. It should be noted that you should avoid using TNT to clear areas when high up in a ravine, as the TNT might destroy the block you were standing on, causing you to fall to your death, you might fall off when running away from the TNT to avoid blast damage, and if you get hit by an explosion and surviving (mostly because of armour) you will probably be knocked off by the explosion knockback.

Because primed TNT is affected by physics, it is used as a projectile which is propelled by an explosion of a TNT charge in TNT Cannons. Also, Arrows attached to TNT will fall off when it becomes a primed TNT. This can be used to create arrow traps.

It is possible to 'rocket-jump' via TNT, by jumping while standing on it just before it explodes. However, this will probably deal damage, and possibly kill you, so it is not recommended.

Both activated and non-activated TNT can be pushed with pistons. No explosion properties or damage levels are changed by the push. Like any other block, it will stop as soon as the piston is fully extended; it is not launched.

Although this may be a bug, TNT can be used to view nearby caves/underground spaces. This is done by using pistons to push TNT into where you are standing. Because TNT is transparent, this will not hurt you, but will allow you to see through all blocks that aren't adjacent to air. (Cave Walls)

Mining
Mining using TNT might be faster than mining by hand but it is impractical for gathering resources; about 70% of the blocks are completely destroyed in the process. In addition, TNT is not very effective when used to mine cobblestone and ores and is only time efficient when mining blocks with a low damage resistance, such as dirt or sand. Nevertheless, TNT can be a part of efficient mining techniques - as the means of removing unneeded layers of blocks and exposing underlying layers. It can also be used for clearing large volumes for underground building projects.

Still Water, Obsidian and Bedrock are the only materials that will resist a TNT explosion.

Normal Lava blocks are also resistant to TNT, and will not be destroyed by it. However, “flowing” lava blocks (those which are in the process changing their flow pattern, not those which display a current) are easily destructible by explosions; therefore, multiple successive explosions (changing the environment around the lava and causing it to flow) may destroy lava.

Water as blast controller
If a layer of water is spread between a destructible block and an explosion, the block will be protected. A one-block-thick water screen will stop most explosions from reaching the other side, however, a player laying multiple blocks of TNT should mind the placement of the explosives, as primed TNT entities may launch each other through the water screen. Using water this way lets you use TNT near an important area, such as a house, base, or ore vein.

Thus, a player can use this to dig a big quarry or hole precisely and quickly by placing a "curtain" of water on the extremities of said hole and dynamiting the center.

Spleef
TNT can also be used in spleef arenas. Because they are destroyed in one hit, they work better than dirt or other materials and do not need a tool to destroy. Make sure nobody has redstone torch, levers, buttons, a pressure plate, Flint and steel, or lava. Another way to make sure it's harmless would be to use a plugin to disable explosions.

Removal
Removing TNT can be tricky, and varies by game. In Survival Test, hitting it two times would stop the countdown and cause the TNT to revert into a resource block which could then be picked up. In Beta 1.6.6 and before, it was impossible to remove it. As of 1.7, it can be picked up like any other block.

Primed TNT
A primed TNT is an entity in Minecraft world. It is spawned at the center (+0.5,+0.5,+0.5) of a powered TNT block, while itself is a cube with an edge length of 0.98. Its fuse lasts 40 ticks if activated by redstone, fire or a random number between 10 to 30 ticks if it's destroyed by an explosion.

Once spawned, the primed TNT is given a vertical velocity of 0.2 m/s, and a horizontal velocity of 0.02 m/s in a random direction between east and north. This directional bias towards north-east is due to a bug. If it does not collide with another block, it will travel 0.166m horizontally on flat ground before it stops and explodes. A primed TNT can be lit on fire in the same manner as arrows can, but it does nothing.

History
TNT has existed in the game since at least the final version of classic. Its functionality was added later.

When TNT was added in Survival Test, it acted similar to how it acts now. Players would have to hit it to prime the block, but could hit it again to cancel the detonation. This recollection of TNT was no longer possible in Indev, and remained the same for a while. During early Alpha, Redstone and mechanisms were added, and those could be used as another way to prime TNT.

Much later in Beta 1.7, TNT could no longer be primed directly by the user, but only by Redstone or any other mechanism that powers the TNT block, as well as by left clicking with Flint and Steel. Hitting the block will simply and safely destroy the block so it can be picked up.

Beta 1.9 pre5 changed TNT's texture, albeit slightly.

Trivia

 * The former crafting recipe of TNT (Sand & Sulphur) actually resembles the creation of gunpowder (Carbon, Sulphur and Potassium Nitrate)
 * It is possible to create a "land mine" by digging two blocks down, placing one block of TNT, placing a block (preferably sand or gravel) directly above it, and putting a pressure plate on top. When an mob or player activates the pressure plate, the TNT will be primed by the pressure plate and subsequently detonated. A similar, yet more potent landmine, can be built by digging two blocks down, placing a dot of restone and digging to the north, south, east and west of the redstone wire.  Place a TNT block in each of the spaces next to the wire and then place a block onto the wire.  Place a pressure plate ontop of that block.
 * The name "TNT" (short for Trinitrotoluene) is technically incorrect. Visually, the block resembles a collection of sticks of dynamite, which is an entirely different explosive frequently confused with TNT. The crafting recipe for the TNT block references the manufacture of dynamite, which is made by stabilizing nitroglycerin with an absorbent material such as sawdust or earth. However, gunpowder is not a component of either explosive.
 * Assuming a cubic meter filled out with 4805 regular dynamite sticks, one TNT block would have the approximate explosive energy of 2.41 tons of TNT (10.09 GJ) in the real world.
 * There are some traps in which the player suspends TNT over a 1x1 long pit and activates it. It will drop into the darkness, hopefully killing any unwanted monsters below it. It is especially useful upon entering a dungeon away from the chest to destroy the monster spawner.
 * An activated or "primed" block of TNT will fall 77 blocks before exploding.
 * TNT appears in the latest Classic mode (0.30), although it is purely decorative and will not prime nor explode.
 * As of Beta 1.7, monster traps can no longer be created by putting a pressure pad directly on top of the block of TNT.
 * Since Beta 1.7, TNT can no longer have torches placed on it. Any torches that were placed previously will disappear.
 * In multiplayer, the burning fuse sound TNT makes before it explodes can't be heard.
 * When TNT is lit and then extinguished by rain it will of course go out. Afterwards, however, clicking the block will cause it to disappear and drop the TNT pick-up, then the pick-up goes away, and the block comes back activated, and detonates as if it were hit before the update making activation possible via fire or redstone only. This only happens with water when it is lit and extinguished by hand with water on the sides and not covering the top.
 * Since the Beta 1.8 update, the smoke textures from TNT explosion have been replaced by shockwaves.
 * TNT Detonated in water or lava will not do structural damage, but still do mob and player damage.
 * TNT can be activated by left clicking on it with flint and steel, this does not use durability. It can also be indirectly triggered by right clicking on it with flint and steel (creating fire detonating TNT), which may give the player more time to flee.
 * As of November 13th 2011, a Sound Update was released: TNT has a new explosion sound.
 * Like the arrows, primed TNT will catch on fire if shot through lava.
 * If TNT is placed with a data value above 0 (with a mod like mcEdit), then it can be activated with one hit, just like before 1.7
 * If a Spawn Egg is set to spawn Primed TNT using a mod, an explosion will follow when the egg is used.

Bugs

 * Use of multiple TNT in SMP will commonly leave visual white TNT blocks. Logging out and logging back in to the server will make them disappear.
 * This might also happen in SSP.
 * When on SMP, if you look at another player holding TNT the letter "N" is displayed backwards.
 * this also works with Endermen
 * In SMP, if primed TNT is pushed off a ledge with a piston, the TNT will appear as if it has exploded where it was when it was falling, but structural damage will be done as if the TNT had never moved.
 * This has not yet been confirmed for SSP.