Glowstone

Glowstone is a light-emitting block found hanging from ceilings and overhangs in the Nether. It can be used as a crafting material, broken into glowstone dust, and is required to fuel respawn anchors.

If glowstone is broken using a tool with Silk Touch, the block drops itself. When a glowstone block is broken using any other tool, it drops 2–4 glowstone dust. If a tool with Fortune is used, it has a higher chance of dropping a large amount of glowstone dust—but never more than 4.

Glowstone only occurs naturally in the Nether, where it generates in crystalline blobs on the underside of ceilings or overhangs. They can be found in every Nether biome, although they are significantly rarer in soul sand valleys,[1] because the ceiling of this biome is made of soul sand or soul soil below which glowstone blobs cannot generate. They can still occasionally generate in caves and canyons in this biome,[2] because the ceiling is made of netherrack.