Indian / penny cleaning

Any suggestions on cleaning old copper coins and buttons from farm fields that have fertilizer. I think I've found an old injun but terriblely crusted. Does hydrogen peroxide work? I've tried olive oil before with very little luck. All suggestions appreciated. Happy new years to alll. Great forum and knowledge here.

Not much you can do once the fertilizer chews them up.

Any that come out 1/2 way decent I just lightly brush with a stiff bristle toothbrush and then leave be because the more you mess with them the more you screw them up.

Here's a good tutorial on "how to" and what NOT to do.

[youtu.be]

there's a thread on findmall about cleaning indian heads:

[www.findmall.com]