Slate

For Pyrite Slate, Click this link. Slate is one of the stone variants found in Ceilum Biomes, and in The Encoren.

Slate is a common decor material, much like the original stone blocks found in every other biome.

Natural Generation
Slate can generate in the Overworld, specifically in Ceilum Biomes, in the form of mineral veins.

Pyrite Slate will also attempt to generate within pockets of Slate

Breaking
Slate can be mined by a stone pickaxe or a pickaxe with stronger strength. If mined with a weaker pickaxe, it will drop nothing once broken.

Wiki

 * Slate has a polished version, (which will be featured in the future when it is created)