Iron: Made Into: Armour
Source: TTT
2 Samuel 23:7
The man who touches them must be armed with iron or with the shaft of a spear. The fire burns them to ashes in the place where they lie.”
Revelation 9:9
They also had thoraxes like breastplates of iron, and the sound of their wings was like the roar of many horses and chariots rushing into battle.