Infested Deepslate is a silverfish-hiding variant of deepslate that breaks almost instantly because Infested Deepslate has a hardness of only about 0.75, far below the hardness 3 of ordinary deepslate. Added in Minecraft 1.18 Caves & Cliffs Part II, Infested Deepslate looks nearly identical to normal deepslate, so players cannot tell the two apart by sight alone. Mining Infested Deepslate without Silk Touch spawns a silverfish and drops no block at all, and a disturbed silverfish can call nearby silverfish out of other infested blocks to form a swarm. Mining Infested Deepslate with a Silk Touch pickaxe instead drops the Infested Deepslate block itself and releases no silverfish.

Infested Deepslate generates naturally only inside Trial Chambers, the structure added in the Minecraft 1.21 Tricky Trials update, and never appears in normal cave or world generation. Builders use Infested Deepslate as a hidden trap block, disguising silverfish ambushes inside walls and floors that look like plain deepslate. The AlaCraft block catalog helps players recognize Infested Deepslate before mining it, so a single careless swing in a Trial Chamber does not turn into a full silverfish swarm.