Ash Block

The Ash Block is a block that covers the upper and lower sections of The Underworld, and can occasionally encase Hellstone. It can be used for building and for growing Fireblossom.

Since it is easy to find, comes in great quantity, and is not corruptible, it is a useful material for creating barriers to stop the spread of Corruption, Crimson, and the Hallow when in Hardmode.