I suppose what I'm looking for is more of a list of special traits ascribed to various metals in folklore, mythology, and popular culture. From there, I could draw on that list for ideas for a specific setting, and reuse the list for many different settings, drawing from it in different ways to get different metallic qualities in each setting that relate back to the list in some way.

The problem with doing searches on folklore and mythology is that you seem to either get things you probably already know (most people, in English speaking countries, at least, are familiar with Greek mythology, and to a slightly lesser degree Norse), or you get a very shallow view of something you're not familiar with but with little to no further information. Like, you might get a list of deities of a lesser known pantheon, but little more than a brief description, if even that. And then doing further searches of specific deities itself tends to lead to dead ends. I've noticed a lot of such articles and websites tend to quote and/or straight up plagiarize one another, some even being word-for-word copies of the Wikipedia text.

I suppose as a substitute I'd accept a source (website, YouTube channel, etc.) for more obscure and less known mythology and folklore. I know someone out there has to know about this stuff and want to talk about it.