Many of us have copper coinage, and it is easy to see, that despite copper's rating as low to moderate chemical activity, most old copper coins are BN or RB, and RD ones are much sought for.

With gold or silver coinage, professional conservation can do miracles, that's why we can see specimens looking like they left mint just hours ago and not 100-150 years ago.

With copper NCS can surely remove all contaminants but can't reverse the flow of time, and if the coin is brown, it will remain so, furthermore, even NGC can't guaranty RD will remain RD in 10 years. Well maybe in some Years NGC will offer special service to encapsulate these coins in 100% hermetic slabs with protective atmosphere of xenon inside...otherwise even today's best cared fore RD's will turn BN in time...

How does it have anything to do with zinc? Zinc is bluish-white metal, far more reactive, and tarnishes much quicker than copper.

Now-days pennies in U.S are minted from plated zinc, which makes them more durable, but what about the pure zinc coins?

In the years 1941-44 German occupation forces introduced coinage in Poland, with the same design as original Second Republic, but made entirely out of zinc. They were introduced in denominations of 1G, 5G, dated 1939, 10G and 20G dated 1923, and 50G dated 1938, but 50G was struck in iron and nickel plated iron.

If one tried to compare RD, RB, BN applicable for copper it would be rd - bluish-white, metallic, RB - bluish black and finally BN - black.

I have yet to see a coin from that period that is fully metallic, most (98+%) of them are black, in fact some years ago, NGC wouldn't even certify them, and return as "corroded". now-days it's still hard to get a zinc certified, bit it happens (see the pic below, upper tier, that's NGC MS61).

Those that would fall under bluish-black with majority of bluish metallic are extremely rare, but oddly not much sought for.

I have been fortunate to acquire one of those rarities, and it is in bottom tier of pic, bit out of focus...

I'm not yet sure if I'll submit this beauty for grading by NGC due to high costs as well as ridiculously long waiting times in Poland...but this little picture below is a great reminder of what NGC's saying:

"Buy The coin, not the holder"

Happy collecting! cheers,

Thunaer

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