Magma Spawns in chunks in the nether similar to how ores are found in the nether but has a higher spawn rate than your average Nether Quartz. They spawn in veins with up to 2-5 Magma, but sometimes generates much more spread out similar to how Emerald ore spawns in the mountain biomes.
Magma appears to have orange dots that are similar to lava and have the animation as lava. What surrounds the dots is a texture of Netherrack. Unlike most ores, this block gives off light similarly to active Redstone ore.
Oddly, unlike most ores, it maintains it's breaking speed no matter what is used to break it, meaning that it will not break faster using a pickaxe or any tool. When destroyed by hand or a tool, it spawns a Lava source block in its place similar to how Ice spawns a Water source block. If the block is broken on top of an air nothing is droped. It has a blast resistance of 2.5, comparable to dirt and Netherrack. When explosions are applied to magma, it drops 0-1 Magma Crystals.
Obtaining Magma Crystals:
The safest way to obtain Magma is to mine it with a silk touch pickaxe giving the player Magma, which they can place in a set area where explosions are safe.