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Aretheus
Gold makes for a good currency because it's rare and basically useless for pre-electrical societies. It's only cool property is the lack of tarnish and easy molding making it good for decoration. I expect the main use for it in fantasy is to bribe dragons to fuck off.
Silver does tarnish, and does so fairly easily. This made it good for detecting acidic and basic poisons, which led to the whole purity and anti-evil stuff. It's probably worth substantially more in a world that actually has magic things weak to it. Distributing it as a currency is a great way to protect your populace against such things.
Aluminum was super rare for a long time because nobody knew how to derive it from the ore that we use today. It's also basically a supermetal, being way lighter than iron while also almost as strong. Anytime you see mithril you can probably just sub in aluminum. Stops being good when steel working is mastered.
and then you have copper as the common, worse than iron metal, tin below that and iron being the actually useful material.