Withered Brick

The Withered Brick is an item that is made by repeatedly smelting the vanilla brick.

Not to be confused with the Withered Bricks, which is the block form of this item.

The vanilla brick must be smelted 8 times in order to go from the Minecraft Brick to the Withered Brick.

(There's a guide on how to make an auto-smelter for these in the Farming Guide.)