Nether Bricks

Nether Bricks are a type of block used to form generated structures in the Nether, making up a majority of Nether Fortresses, forming their walls and supporting pillars. Nether brick does not generate anywhere else in the nether.

Nether Brick is non-flammable and immune to Ghast fireballs, making it a suitable shelter material for the Nether. Nether brick blocks take approximately one second to mine with a stone pickaxe, slightly faster than Overworld stone. Its default texture appears somewhat similar to a brick block, but differs in both color and detail. When walking on it, it makes the same step sound as stone.

As of version 1.5 (snapshot 13w01a), the Nether Brick block can be crafted from Nether Brick (Item). Besides building with it directly, Nether Brick can be crafted into Nether brick stairs, Nether brick fences and Nether brick slabs (all of which retain its fire and blast resistance).

Natural Occurrence
Nether brick can be found forming generated structures in Nether fortresses.

Trivia

 * In the regular Brick blocks and items have different names (Block "Bricks" Item "Brick"), but Nether Brick blocks and items have the same name (Nether Brick).