Updated to 1.20
Magma blocks are quite interesting. You can find them in the Nether or in ocean Rifts, where they can be used to restore your breath and let you breath underwater. They also give burn damage to whoever walks on top of them, mobs included.
They are a light source, even if their light level of 3 is not enough to prevent hostile mobs from spawning or to prevent water from turning into ice.
Magma blocks can also be used as decoration blocks or to make air bubbles elevators but, being similar to Lava blocks, players often wonder if these blocks can start fires as well and destroy hours of their work in few minutes. In this article we are going to see if Magma blocks can actually start a fire and how to use them in a safe way.
Magma blocks and fire
So, do Magma blocks burn wood? Quick answer: no. Longer answer: well… let’s see.
We all saw Lava blocks starting fires in the surface and destroying trees that were nearby. They can set on fire many different blocks, but Magma blocks aren’t one of them. But if you set the top of the block on fire, this will burn forever, just like Netherrack.
As said before, Magma blocks give fire damage if you walk on them (it can be prevented by wearing Protection and Fire Protection enchanted armor). That’s why mobs will try to avoid them and Spiders will not climb on a wall made of them (Cave Spiders will though).
Most mobs (all the Overworld ones) can’t spawn on top of them either, making them one of the blocks that you can use to build a mobs-free dark area.
So, if you decide to use them for any of the reasons above, don’t worry: Magma blocks can’t set other blocks on fire. But if you decide to set on fire the top of a Magma block, this will be able to spread if it finds wood nearby.
They don’t even set players or mobs on fire, when they walk on them. So, if you don’t set them on fire, they are perfectly safe and you can use them in wooden buildings without having to worry.
Other than being useful for building an underwater base (so that you can breath while swimming in the water outside) and against mobs, Magma blocks can be useful against other players.
You can build a massive area of Magma blocks and cover it with blocks that are the hight of a Trapdoor or lower like Snow layers or Carpets. This way, Magma blocks will still deal damage to players and mobs walking on top of the Snow layer/Carpets/others.
On the other hand, you can walk on top of them without getting any damage by using Frostwalker enchanted Boots. This way you can put yourself ahead of your enemies.