Deepslate

Deepslate is the stone type that makes up almost every solid block below Y=0 in the Overworld. Stone gives way to it gradually between Y=8 and Y=0, and from there down to bedrock it replaces stone entirely. It also generates in great quantities in ancient cities.

Deepslate needs a wooden pickaxe or better to mine and drops cobbled deepslate; broken with any other tool it drops nothing, and Silk Touch is required to collect the block itself. Cobbled deepslate can be smelted back into Deepslate in a furnace. With a hardness of 3 and a blast resistance of 6 it takes twice as long to break as stone, which is what makes mining at depth noticeably slower.

Like a log, Deepslate can be placed along the x, y or z axis, and its texture orientation varies with position so large expanses do not look tiled. In a stonecutter it becomes polished deepslate, deepslate bricks and deepslate tiles, along with their slab, stair and wall forms. Ores that generate at this depth appear as their deepslate variants, so most of the diamond, redstone and lapis a player mines is embedded in Deepslate.