Darkened Rock can be mined up with any pickaxe. If mined without a pickaxe, it will drop nothing.
Darkened Rock makes up the stone layer in Dustopia, below the surface, similar to stone in the Overworld.
Darkened Rock also appears in the pillars that hold up the cages found throughout Dustopia, and in the primordial shrine structure.
Darkened Rock serves solely as a building material and as a decorative block.