Nahkampfspange (CCC) Help!

[Joshua R]

I got this a couple years ago. It was dug up from a bunker in Kurland Pocket. I was wondering if anyone knows a way I could clean it up. It is not rust (I do not think, as it does not have any real color and looks and feels almost like dirt or maybe even concrete). I want to clean it up to see the color behind the rust/ dirt. There are a few parts on the clasp that have clear crisp color and it looks a lot like gold. So does anyone have a good way to clear all off the gunk off? Thanks!

Josh

[MAP]

I've never, but I know some people use Oxalic acid on ground dug helmets. It typically leaves the decals and paint intact. That said, not sure how it would affect a gold/silver/bronze wash