Tuff

Tuff is a porous rock, made from volcanic ash, found as part of Amethyst Geodes.

Natural generation
Tuff generates naturally as part of the structure of Amethyst Geodes, in the outer layer.

Breaking
Tuff drops as an item if mined by any pickaxe. If mined by any other tool, it drops nothing.

Usage
Tuff is currently used only for decoration.