I wasn't really sure what part of the forum this would be appropriate for, so a mod can move this if it's in the wrong place.

I was thinking about various materials and how they could be expanded upon to have magical properties of some sort. Everyone knows that werewolves are weak to silver, or that fairies are weak to cold iron. This is the sort of thing I'm talking about.

I did a brief google search to see if I could find anything from folklore on these sorts of materials, but I'm not finding much. According to Wikipedia, the metals of antiquity are gold, silver, copper, tin, lead, iron, and mercury. So maybe those would be a good place to start. Note that bronze is a metal alloy (of copper and tin), rather than an elemental metal.

My initial thoughts are that gold should have some connection to the sun, like silver does to the moon. Maybe gold would harm vampires (like stabbing them with sunlight, essentially). Perhaps light reflected off of gold would have the same properties as sunlight (and likewise we could do the same for silver and moonlight). I kind of thought there would be something about gold in Native American folklore, but my research so far hasn't turned anything up. Gold could also have a connection to immortality, as a metal that does not rust or tarnish.

Copper was apparently associated with Aphrodite, but I'm not sure how that's significant or useful yet. Orichalcum, a mythical metal from Atlantis, also seems to have some relation to copper or bronze. It has obvious electrical properties, but those wouldn't have been known back then (I don't think?).

Mercury, being a liquid at room temperature, seemed to be known for it's mutability. Apparently it was commonly used in alchemical transmutations because of this. Apparently, it was also thought to bring healing and long life, despite the fact that it's actually really, really toxic. Mercury is tricky, because you couldn't really make things like weapons or armor out of it, since it was, as previously mentioned, a liquid. You could probably use it like holy water, though, splash or sprinkle it on things.

I thought I'd be able to find a little more on these just by searching, but I'm coming up mostly dry. Maybe someone better versed in these things could chime in.