Lava

Lava is a fluid block which emits light and sets things on fire.

Natural occurrence
Lava primarily occurs in large magma pools deep underground, on levels 0 through 12. It can also occur as lava rivers from a single spring block, pouring down caves into pools.

Since Alpha 1.2.6, Lava also occurs in lakes. They are rare and can be found at any elevation within any biome, and can cause forest fires. Lava lakes vary in size and depth, and will carve out a small ceiling area above them when generated below the surface.

In the Nether, lava is extremely common, and has the frequency of water. Lava also pours from the ceiling.

Burning



 * Most entities, including players and mobs, will take damage every second from being in contact with lava, in addition to being set on fire. If the player touches water during this time, the fire will be put out.


 * TNT, bookshelves, leaves, wool, fences, wood, planks, and wooden stairs are flammable. If flammable blocks are within 3 meters of lava, they will eventually catch fire. Non-flammable blocks block this effect, but not the spreading of active fire. The “embers” or “fireballs” which fly out of lava are purely decorative and do not directly cause fires.


 * Lava does not ignite anything below it, just above it and to its sides. This can create interesting structures.


 * Warning: If you are playing on peaceful difficulty, it is still possible to die. The regenerating hearts and loss of hearts from being on fire will simply counteract each other, and the player's hearts will fluctuate by only a half a heart, keeping them alive and giving them longer to find water. However, if you stay in the lava itself, you'll lose hearts much more rapidly and die.

Flowing
Lava flows far slower than Water, and sometimes sourceless lava flows will linger for a very long time. It flows 3 blocks horizontally from its contact point, vs. water's 7. See Fluids for detailed information on how lava and water flow.

The interaction of lava and water:
 * If lava flows horizontally into water, Cobblestone is created. Using this you can create cobblestone farms.
 * If lava flows vertically into water, the water is removed.
 * If water flows horizontally into lava, a hiss and puff of smoke occur but nothing changes.
 * If water flows vertically into lava, Cobblestone or a hiss may result.
 * If water flows into a lava spring then Obsidian is created.
 * If vertically falling water touches still lava on any side Obsidian is created - even if the water would not run into the lava's square.

The primary natural source of obsidian is rivers flowing onto the surface of magma pools in deep caves; care should be taken if mining these since there is usually a layer of lava under the obsidian.

Lava which is flowing will destroy the following in its path: wheat, flowers, mushrooms, levers, both types of torches, redstone wire,and rails. Note it doesn't flow over plates, fences, or even wood or wool blocks. Sugar cane holds back lava, but will disappear if the Sugar cane's water source is destroyed by the lava.

If lava falls onto redstone wire bordered by water, the redstone turns into obsidian, with no loss of lava. This is considered a bug; see the section on Obsidian for more information.

Using a redstone wire, a one-block lava flow can be redirected by supplying power to the spring block, which will cause it to reset the flow towards the now-nearest terrain depression. This is further elaborated in this thread. It cannot, however, be reversed. This re-calculation is made because redstone wire when toggled changes the block from redstone(on), to redstone(off). Whenever a block updates on any side of lava, the lava re-calculates where to flow, but does not cut off its current direction of flow.

Lava Bucket
You can collect and place Lava springs using a Bucket. As with Water, you can only harvest the springs, not the flowing lava coming from them. Unlike water springs, lava springs cannot be duplicated—there is no way to create lava and it is not a renewable resource.

Lava can be used to make obsidian, to light an area, or to create traps. When used to create obsidian, water will be used to cool the lava either before collecting it with a diamond pickaxe in a mold in the desired shape, or by emptying the bucket next to an artificially created waterfall.

Lava can be placed in a furnace in a bucket to be substituted for coal. Its burning time is 1000 seconds, compared to 80 seconds for coal (100 smelts vs. 8). Using a lava bucket as a fuel source consumes both the lava and the bucket.

Lava can also be used as a bin, by creating a 3×3 box of any unflamable block and leaving a 1 block gap inside. Pour lava into it and drop unwanted items.

It can also be used a light by using glass as the wall. It is also a good idea to have a contained water spring next to it, or to carry a bucket of water.

History




Classic
In Classic, lava spreads by duplicating itself to open horizontal and downwards squares like Water. Lava is slower, though, and can be easily outrun. A quick player can block the flow of lava by building a dam. However, if the lava wave is large, a player may not be able to build fast enough. Also like water, lava slows down the player moving through it but it does so to a greater extent, and swimming through it causes greater damage. Lava is also more opaque than water and is harder to see through while you are submerged; you cannot see through lava from outside it. At the bottom of the map, lava can be found directly above bedrock in a different form, as it will trap the player and prevent the player from leaving unless water is let in and collides with it or if the player places a sand block, letting it drop into the lava. If water is let into the area where the Lava is, the lava will form Stone, allowing the stone block to be removed to expose Bedrock underneath.

Survival
Since Infdev, lava flows more realistically across surfaces but not as much as water does. Lava will flow for a total distance of 3 blocks away from the source block (further in The Nether). Just like water, lava will flow in a single line towards the nearest terrain depression within four blocks. Items thrown into lava flows will disintegrate. All objects burn instantaneously when dropped into lava. Arrows will not disintegrate, but will appear to catch fire and can still be picked up.

Lava is no longer present at the bottom of maps in this mode. Lava can melt ice and snow, much like torches can, but melt a larger area. Lava is luminous and a large lava flow is visible in the dark from quite a distance.

The creation of Obsidian was added in Alpha v.1.0.6_03.

In Beta, lava is less reactive with horizontal water flows.

Since the 0.0.19a client update on June 20, 2009, Lava's texture became animated.

As of Seecret Friday Update 9, buckets of lava can be used to fuel a Furnace for 100 smelts.

Trivia

 * Lava is only called lava once it reaches the surface, and is called magma when underground. As such, most of the 'lava' in Minecraft is actually magma.
 * Lava can be contained by surrounding it with snow blocks, because they are not flammable and do not melt.
 * Lava can be useful as a protection for many buildings, as an example, when building a base, as you can make a moat of lava around the building to protect it against aggressive mobs.
 * An easy way to 'fill-in' large pools of lava is to use gravel or sand, which will fall to the bottom of the pool and stack upwards.
 * An easy way to find lava is to press the "F" key and look for square embers.
 * Before the December 3rd update, right-clicking a furnace/workbench/chest while holding a lava bucket would leave you with a lava spring on top of the said item, but now it just opens the inventory as it would have if you were carrying nothing.
 * By placing blocks of lava (obtained by an inventory editor) on top of a single block floating in an ocean,(or on a 1x1 tower of blocks built up from the bottom of the body of water,) the lava will continue to flow underwater, with the lava at the bottom turning to cobblestone.
 * You can see the stars when in lava, even if it's supposed to be translucent.
 * If an item falls into the edge of a lava pool, it may pop back out and appear as is it were burning. Also, you can pick the item back up once it's back on land. More common in SMP.