Item from Mistborn by Brandon Sanderson
Ruin's god metal, condensed from his power into crystalline beads. When burned Allomantically, grants the ability to see a few seconds into the future. The most valuable substance in the Final Empire.
Atium is Ruin's body made physical — his power condensed into a burnable metal. When an Allomancer burns atium, they see ghostly afterimages of everyone nearby showing their movements a few seconds into the future, allowing near-perfect combat prediction. Only another atium-burner can counter this advantage, creating a feedback loop of prediction. The Lord Ruler hoarded atium as both currency and strategic resource, controlling the Pits and distributing small quantities to keep the nobility dependent. Kelsier's destruction of the Pits' crystal geodes was a devastating economic and strategic blow. In the final battle, the hidden atium reserve was burned by Elend's army of Allomancers, denying Ruin the ability to reclaim his full power.
Small, translucent crystalline beads with a silvery-grey sheen. They form inside geodes found only in the Pits of Hathsin, growing slowly over time. The crystals catch light with an otherworldly gleam that hints at the divine power they contain.