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it's not so uncommon, really. you can find a lot of copper, nickel and iron rich soils where i live plus there's also bauxite (aluminum) and lots of chromites too and those are usually hard to process in some instruments so this is ideal for them at times

Ah ok, I was more thinking about precious metals.

well when it's precious metals, there are already effective methods for those, otherwise this method is for common and industrial metals

Thanks for clarifying 👍🏻