Iron

Vanilla
See the various pages on the Minecraft Wiki for information on Iron.
 * Iron Ore
 * Iron Ingot
 * Block of Iron

GregTech
Retep, please fill this in.

Flaxbeard's Steam Power
Flaxbeard's Steam Power only adds the plate variation of the Iron material. The Iron Plate can be created by throwing Iron 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 Iron Plates.