Elementium

Botania
Elementium Ingots are created by throwing 2 Manasteel Ingots into a Portal to Alfheim. Throwing two Blocks of Manasteel into a Portal to Alfheim will return one Block of Elementium.

Flaxbeard's Steam Power
Flaxbeard's Steam Power only adds the plate variation of the Elementium material. The Elementium Plate can be created by throwing Elementium Ingots into a heated Crucible, and then pouring that molten metal into a Mold with a Plate Mold. Six nuggets are used in the creation of a Plate, which makes it unable to be used in other mod's recipes requiring their own Elementium Plates.