Demonite Brick

It looks like the Corruption without behaving like it. Ebonstone creeps, this does not, so you can face an entire build in dark purple stone and drop it in the middle of a clean biome without watching the surroundings turn. That is the main reason to bother crafting it instead of building straight out of the raw stone.

Explosives punch through it, so it is a poor pick for anything you want to survive a stray bomb, and it throws off a low glow that reads as faintly lit rather than dark. Supply is never a worry. Every Wall of Flesh kill on a Corruption world buries the drops in a shell of it, so you can keep topping up as long as you keep fighting.