I know almost nothing about coin collecting. I know even less about Chinese coins. Has the corrosion destroyed whatever value these coins had? I'm considering either putting them in mineral oil for several months or else ordering some of that verdicare stuff. If anybody has any information on these coins and their value, I'd be obliged to hear about it. All thoughts on preservation and stopping that corrosion would be welcome also.
Thanks,
Casey
The images below are of three coins, front and back.





