Lumium is an advanced alloy added by Thermal Foundation. It consists of Tin and Silver in a 3:1 ratio, with Energized Glowstone added to the mix. The alloy gives off a bright glow that can be easily manipulated in controlled environments.
Empty Buckets are returned upon crafting Lumium Blends.
Lumium is commonly used in devices that can emit (controllable) light. Currently the alloy doesn't have many uses in practice; in Thermal Expansion there are only about three things that use Lumium in their crafting recipes.