I just received my 2016 Gold Mercury Dime in the mail today from the US Mint, and there is a small red spot on the obverse of the coin.... with dark red spot (size of a needle) in the middle and then red circle around it (looks like the first ripple if you dropped a stone into water). I'm going to return the coin, but curious what this could be.
It's an impurity. Perhaps an irregular bit of alloy, but more likely (to me) something external which got struck into the coin and then proceeded to corrode more widely. Kinda makes my point about this second round of Gold Mercury sales - they're almost certainly coins which already got returned once.
These are (according to the Mint) .9999 Fine, 24k. Therefore, never mind my comment above about alloy.
So, I guess we might conclude that the tiny spot on the coin could be the 1/10,000th part that is copper. Chris
Instead of repeddling coins that have been returned because of problems, why doesn't the Mint just melt them?
If you research the old threads on gold-toning-red, you will find many theories for this. I favor the quantum theory effects of the "metallic bonding" of these metals.
It doesn't much matter which theory you choose for in the end the conclusion, or end result if you prefer, is the same - gold tones. That said, with this example posted by the OP, I don't think that's toning - I think that is staining. In other words a small particle of foreign material somehow deposited on the coin has caused the discoloration. Similar things are commonly seen on all types of coins. Whenever you see a small circular and very dark center with a fading to lighter color ring around it, it's almost always due to foreign material having been deposited on the coin. Even tiny droplets of saliva can cause similar effects.
Well I guess this likely confirms the mint did in fact resell all prior returns in this last release of stock.
