Erethium – A Rare Crystal Found Deep Below the Surface

Erethium is a rare, glowing mineral found only in the deepest parts of the world—below Y-level -48 in small clusters near lava pools or geode-like caves. It appears as a pulsating, dark violet crystal with reflective shards and emits a soft ambient light.

Erethium can be used to craft tools and armor stronger than diamond, but more unstable—making them powerful, but with a twist: Erethium gear becomes more powerful the lower you are underground. Erethium tools could gain buffs like Haste or Night Vision when used underground.

It would also introduce a new beacon-like block called the “Erethium Core,” which activates only when placed below deep slate level, giving nearby players underground bonuses like resistance or strength.

Erethium isn’t meant to replace Netherite, but to encourage late-game underground exploration and create a deeper risk-reward system.