Netherrack

Hellstone (aka Bloodstone, Netherstone, Red Mossy Cobblestone, Brimstone) is a stone that is found only in the The Nether. It burns indefinitely, so it is a good way to have everlasting light. It also has an extremely low resistance to TNT, and can be mined with as little as a stone pick with one hit. The dark red of the stone, along with its abundance in The Nether give it a very chilling ambiance, and also make the region seem darker than it is.

It is possible that the official name of this stone may be Netherstone. (Unconfirmed)

Although it is very common in The Nether, it has no use in crafting.