copper spots on gold coins?

icollect

Hi everybody, I've been here for a while, but just got an account and here's my first post and question.

How the copper spots get on the gold coins like this? And what makes me more confused are,
1. They are 999 gold coins.
2. They were sealed when they were minted.
3. Some of them get it, but some of them don't.

Steve27

"How the copper spots get on the gold coins like this?"

If those plastic holders are made of PVC then that may be your answer. Are they relatively soft and pliable?

cosmicdebris

Anything I have seen from the Chinese mints have been wrapped in PVC.

cosmicdebris

Oh yeah I forgot. Welcome aboard

theboz11

Welcome to the forum, copper is the other .001 ,but I have had a number of Pandas and never had that show on them. Even in US Gold where the copper content is higher, you usually only see small pin head size spots.

icollect

Thank you everyone for your quick answers! And here comes the new question,

How long is takes to have those copper spots to be shown after a coin was minted? Will they ever stop growing? I'm thinking should I wait for a certain years before buying them.

theboz11

Depends on the thouroughness of the blending process,,If that wasn't a 1982 I would recommend taking it out and trying a acetone rinse on it.

What size are those Pandas?

icollect

They are 1/10 ounce pandas, but not mine. Some of my gold coins have the same problem, but the spots are not as big as this one. Just use it as a demo.

The panda's original holder is a bit soft, but I thought the mint wouldn't use PVC holders. They mint coins after all.

theboz11

In 1982 PVC was the standard, it became obvious later and the big change to Harder flips occured. Copper spot are generally small and generally a very good indicator that the coin is real.

Askari

Welcome, icollect!!


<< <i>How long is takes to have those copper spots to be shown after a coin was minted? >>

A lot depends on the environment in which the item is stored. Real copper spots tend to stay small; it all depends on how even the mixture was, as Boz said. Unless neutralized, PVC continues damaging the coin. Just removing it from the flip won't stop it, although it will tend to slow down. A good acetone dip should neutralize it. Never having had that on gold, though, I don't know if it will remove it. BTW, you should dip all of your gold coins that were in PVC flips. Just because the damage hasn't begun to show doesn't mean it's not there.

earlwbollinger

Well first even .999 pure gold coins have some impurities in them.
Copper tends to be the most common impurity. For example usually Mexican gold coins tend to look more reddish like
copy coins instead of gold. Sometimes a sittle silver gives the gold coins a more yellowish appeance or even more light color.

The PCV wrapper or holder is notorious for damaging coins as the PVC plastic starts to break down and deteriorate releasing various corrosive chemicals into the small area around the coin.
Those gases or chemicals likely caused the gold and copper to break down a little and leach out onto the surface more, yeilding coper spots and spotches. The copper part will likely turn green next.

Plus the gold planchettes may have had defects in their making, where some plancettes may have more copper in portions of the planchette than others. That would aggravate the condition you see even more.