Celestial Uranium

Celestial Uranium is one of the seven prismatic ores of YGGDRASIL.

Description
Celestial Uranium is a critical element for the Caloric Stone. In the past, Ainz Ooal Gown discovered through a stroke of luck that by gathering vast quantities of this prismatic ore and then expending it, they could earn the Caloric Stone, an expendable-type World Item. Presumably, this metal was found in the Seven Hidden Mines.

Trivia

 * Although Punitto Moe believes that there could be other sources for finding the ore, the mine discovered by Ainz Ooal Gown was, apparently, the first mine with Celestial Uranium discovered on the game.