Deepslate

Deepslate is a stone type found deep underground in the Overworld that functions similarly to regular stone, but takes significantly longer to mine.

Deepslate can only be obtained by mining it using a pickaxe with the Silk Touch enchantment, otherwise it drops cobbled deepslate. If broken with any other tool, it drops nothing. The breaking time for deepslate is twice the time for stone.

Deepslate makes up the majority of the solid blocks generated below Y=0 in the Overworld. Stone is gradually replaced from Y=8 to Y=0 until it is completely replaced by deepslate.