Forum Quotes Re: Why The Fair Folk are harmed by Iron (forum.prg.net)

"Just to add some irrelevant science to the mix, iron is also the element that eventually stops stellar fusion processes cold. Fusing iron sucks down more energy than it can produce even under ideal circumstances.

So, the obvious answer is that fairies are fusion powered."

Response from someone else

"You left an important bit out! Iron is both the lightest element that can't be fused to gain energy, and the heaviest element that can't be fissured to gain energy. In other words, it's (sort of, in theory) possible to obtain energy by transmuting any element except iron."