Part 1 can be found here [No Iron for your fair-folk maiden? (Part 1)](https://worldbuilding.stackexchange.com/q/147441/46406)

And part 2 can be found here [No iron for your fair-folk maiden? (Part 2)](https://worldbuilding.stackexchange.com/q/147792/46406)

So, my not so metal inclined Fair-folk are encountering iron and other related metals near its group in the periodic table and they find they really don’t agree with them in any of their refined forms. For some specifics: 

1. Iron burns fair folk and disrupts their abilities.
2. Titanium causes their powers to feedback and hurt themselves.
3. Osmium dissipates all their energy based abilities, think perfect shielding.
4. Tungsten causes necrosis on contact.
5. Nickel (which is both iron type and silver type) causes bleeding wounds.
6. Cobalt (which is also an iron/silver type) renders the afflicted body part unable to channel energy through it.

In addition, all of the iron type metals disrupt fair folk abilities. Which basically means that they can more easily push through their shielding and “ground out” their attacks.

The basic premise of all of this is that all iron type metals cause direct harm to fair folk. In addition, it doesn’t matter if the metal is touching their skin or inside their bodies, **as long as it is in a refined form** it will have the same effect. The effect ends immediately once the metal is removed, or once it reacts, such as forming an oxide.

So here is my question: what would cause these iron type metals to harm fair folk so severely?

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To open this question up a bit I’ve decided to remove the “no chemical reaction” part of its limitations.