A World War II Lincoln Cent Error – Off-Metal Mystery in Gem Mint State Discovered
Key Highlights
- New discovery: A 1945 Lincoln cent error struck on an alloy containing 12% silver
- Two leading theories: Experimental wartime test strike or accidental alloy contamination
- Unique metal composition: Does not match any U.S. or foreign planchet used by the Mint
- Gem Mint State example with striking silver-grey color
- Expert research by Roger Burdette, authority on WWII experimental coinage
Photo by Mike Byers – A World War II–Era Off-Metal Mystery in Gem Mint State – Obverse
A remarkable new wartime mint error has surfaced—one that is already generating buzz among error specialists, pattern collectors, and WWII-era researchers. A previously unknown 1945 Lincoln cent struck on a silver-bearing alloy has been confirmed, and its unusual metal composition raises compelling new questions about U.S. Mint activity during the final months of World War II.
The newly discovered cent, preserved in Gem Mint State, immediately stands out. Instead of the typical copper coloration expected for 1945, this piece exhibits a striking grey-silver appearance. Metallurgical analysis revealed a highly unusual alloy of 83% copper, 12% silver, and 5% zinc. Even more surprising is its weight of 3.61 grams, noticeably above the 3.11-gram standard for the period.
A Composition That Should Not Exist
One of the first steps in analyzing the piece was comparing the alloy to known planchets struck by the U.S. Mint for both domestic and foreign coinage. The Mint Error News 69-page reference, widely regarded as the most complete catalog of these materials, shows no matching composition. The alloy is not consistent with any coin the Mint produced for the U.S. or for foreign governments.
That absence opens the door to two highly intriguing possibilities.
Expert Analysis Points to Wartime Alloy Contamination
To understand how such a hybrid planchet could have been created, the coin was evaluated by Roger Burdette, distinguished researcher and author of United States Pattern and Experimental Pieces of WW-II. Burdette’s wartime research is considered the benchmark for identifying off-metal and experimental strikes from this era. [See letter below]
According to Burdette, the most plausible explanation is accidental contamination with War Nickel alloy material. From 1942 to 1945, the Mint produced five-cent coins using a silver-manganese alloy to preserve nickel for the war effort. Although the War Nickel formula does not perfectly match the composition of the discovered cent, Burdette suggests that leftover or scrap silver alloy from nickel production may have been mixed into cent strip, producing the anomalous 12% silver content seen here.
The resulting planchet, heavier, silver-toned, and chemically distinct, would have blended into normal cent production unnoticed, creating the rare off-metal strike now identified.
Source material – Roger Burdette’s Letter to MiKe Byers reproduced below:
February 11, 2025
Mike,
The coin photos arrived OK.
A standard 1945 cent has a calculated density of 8.8685 g/cm3. Your 1945 cent has a calculated density of 9.0521 g/cm3, which is about 0.1836 greater than normal due to the silver content.
Nominal weight of a 1945 cent is 3.11035 grams (48 grains +/- 2 grains). The slab weight of your coin is 3.61 grams, which is about 0.5 gram greater than normal.
Considered together, and assuming minimal deviation from expected values, your coin should weigh 3.6814 grams or about 0.0741 grams (1.144 grains) heavier than reported on the slab. This discrepancy is within the legal tolerance; or might be due to measurement error in weight, or rounding error in XRF measurement, or poor XRF technique.
None of these explain the silver content.
From knowing that both normal alloy cents and wartime alloy nickels were in production at the Philadelphia Mint in 1945, an initial speculation might be cross contamination with the 56% copper, 35% silver component of five-cent coin alloy. (Copper and silver were prepared and mixed separately from the 9% manganese.)
To see if this is a plausible conjecture we have to examine Philadelphia Mint melting operations in 1944-1945 – the only years that both shell case brass, pure copper, and five-cent wartime alloy were in simultaneous use.
Normal operation for 1944 cents (and 1945).
To return one-cent coins to the pre 1943 alloy and quell complaints about zinc coated steel cents, the War Production Board encouraged use of expended 50cal shell cases for cent coinage. By November 1943 a suitable compromise had been agreed to. The Mint did not have suitable ventilation and annealing equipment to melt brass shell casings. Contractors melted 70% Cu, 30% Zn shell cases into brass bars. The brass was supposed to be assayed to ensure compliance with the contract. However, Dir. Ross’ memo to Shanahan, Superintendent of the San Francisco Mint states:
“While the specifications in the bid invitations provide for assay certifications it is not contemplated that the shell ingots will be kept segregated by melts as is done with silver. It is expected by all concerned that the shell-ingot melts will run sufficiently uniform in composition to satisfactorily permit their use without consideration of the probable small variations, particularly since the 5 to 1 ratio of added virgin copper will materially diffuse the shell-ingot variations. In other words, it is anticipated that the indicated procedure will produce coin practically within the limits of the legal composition.”
Normal cent coinage alloy was made by combining one (1) bar of shell case brass and five (5) times the brass’ weight with pure copper. (A proportion of 5 Cu: 1 Brass.) This produced a normal 95% Cu, 5% Zn alloy. A trace of tin was added co comply with the coinage law.
If a bar of the 5-cent coin alloy 56% Cu, 35% Ag without Mn were substituted for one of the pure Cu bars (same weight) the resulting alloy would be 89% Cu, 6% Ag and 5% Zn.
If two bars of this same 56-35 alloy (same weight) were substituted for two bars of pure Cu, the alloy would be about 82.82% Cu, 12.03% Ag, 5.16% Zn. The calculated alloy density would be 9.0505. This “two bar” substitution is too close to the reported XRF to ignore.
It also uses what we currently understand about mint operations for shell case brass and wartime five-cent alloy. The director’s comment about not assaying shell case bars might also indicate a pervasive assumption that the alloy resulting from the 5:1 ratio was “good enough not to be tested,” and that little attention was paid to possible alloy ingot or strip color differences.
That said, we cannot prove this kind of accident occurred. It is, however, all I can come up with given the current limited state of operational detail and the overall coinage operations in 1945.
Last, in looking at the photos you sent, I have an impression that the two 1945 cents are a product of different hubs. But, you have the coins in-hand and are in a much better position to make that determination. This is unlikely to affect anything involving the two coins, but is mentioned for completeness.
Roger Burdette
Could It Be an Experimental Strike?
Another scenario cannot be dismissed: the coin may be a wartime or immediate post-war experimental test strike. [Mike Byers’ web site The Mint Error News has a 69 page report of coins struck by the U.S. Mint for foreign countries. It is the most comprehensive report available anywhere. This 1945 Lincoln Cent Off-Metal does not match any known planchet composition for U.S. or foreign coins.] The Mint was evaluating materials and adjusting supply chains as wartime restrictions eased. Yet even among documented test pieces, no known experimental cent matches this alloy, placing this discovery in a category of its own.
A Significant Addition to Wartime Error Scholarship
With its silver content, unusual weight, and unmatched alloy, this newly discovered 1945 silver-alloy Lincoln cent is already being viewed as one of the most important wartime mint errors identified in recent years. Whether caused by alloy contamination or produced as a late-WWII experimental piece, its existence adds a fascinating new chapter to the study of U.S. Mint operations during the era.
I have error coins. Unique collection
It looks like I have a reason to have a better look at my cent collection again.
What an insane error to find so far after the original minting.
Yeah, and the cheapest to detect either.
Yay another minting variety to be on the lookout when coin roll hunting.
WOW!! Still, in 2025 we are finding mint coinage errors.
An absolutely incredible story and find. I assume it will up for auction at some point in time.
Very interesting article I have a 1934 that it looks like the copper is flaking off and there’s shiny metal underneath. After reading this article I do believe that I’m going to try to get the money and send my penny in to have it examined
Now I’ll need to go look through all my wheats again!!! Great Article!
WOW! Time to check my penny collection.
Experimental or error would love to find one for myself
Love to see if more are found in the next few years
Looks like black and white photos of a regular copper cent.
Time to get the scale out!
This is a crazy discovery coin.
Great mystery for someone to figure out where the planchet came from.
The composition of the Cent is fun to read about. You have to wonder what a modern copper nickel cent would look like.
if you have war coins is the only way to ck by weight?
Time to weigh all my steelies!
Time to check my penny collection
The odds of learning the truth about the origin of this coin can’t be good at this point.
This makes me want to keep looking.
Have to dig out my 40′ wheat cents
Crazy! Looking over my “junk” wheat cents I still have. ;)
I love this
What a neat find!
will be checking out my cent coins for sure
Wild stuff. If this coin is a true error and not some sort of experimental strike, I wonder how many others of these are still lurking about.
Just after I sold all of mine
Error coins are fascinating to read about.
I saw someone on Facebook claiming they had one like this, crazy!
Perfect project for my grandson, reexamining all the wartime cents in “our” collection!
Absolutely fascinating!
Glad I’ve yet to go through my 50 year cent accumulation with my Digital Scope. Another possibility to entertain!
Such an interesting coin! I love the analysis of the alloy and the work to figure out where it came from. Very interesting!
Great article! I hope Coinweek will keep us posted on any new developments about these coins and if any more are found.
Interesting article! I have an old gallon glass apple juice jug completely filled with old pennies.
It seems the most plausible is an employee using a homemade concoction whil at work.
Fascinating that new errors are still being discovered in coins so old, but how was this coin discovered? The article leaves it entirely up to the imagination, but that should be an interesting enough story to merit its inclusion. Was it sitting forgotten for 80 years in a closet at the mint, did someone find this in their grandad’s collection of pennies, or did it miraculously show up in someone’s change?
Wow, one of the coolest mint mess ups I’ve seen.
Lincoln and silver together?
Wow ! What a find, 80 years later
Amazing find! Had no idea something like this could even occur.
Fascinating. Eighty years is a long time for such an incredible find to be manifested so well preserved.
sounds like monkey business to me
THAT would be a cool find.
That’s going to be worth a fortune!
Great work. No im going to go thru my wheaties again. Awesome.
I love seeing new error discoveries!
Very interesting article! Learn so much from these articles.
Wow! Would I have loved to have found this.
What an amazing find! What stories it could tell….
You’d think there would be some records of how this happened!
I love these old cent coins
This looks like a modern Chinese mint trick. I have a hard time believing that no one would have noticed a mint state coin of this type for 75 years. A coin like this would never have been found in circulation. It would have been the star of a private collection. Would the owner not have shown it to another collector? No, this is a modern fake that was made specifically to fool fools.
Silver! and the current coins are costly? [Teehee!]
Something unusual.
There are still interesting discoveries out there, this was unknow for 80 years.
Amazing. I will have to go back thru my coins to see what I have. I never would have guessed.
incredible find
Fascinating that it took so long to find it
My thoughts ( for the 2 cents they may be worth ), if it was an experimental piece, wouldn’t there be documentation regarding it by whoever made it? 2. If accidental contamination is the cause, and it got swept into circulation, i think there could be more, BUT given its great condition i think somone plucked it out of the machine or conveyor belt and kept it. Either way, its a mystery and so far. . A one of a kind.
This is just plain crazy, considering the composition of the silver alloy does not match that of any other coins the United States has ever minted, domestically or for foreign nations.
Sure wish I found it.
It doesn’t seem like they could have accidentally added in extra silver, since replacing two bars of copper for two bars of the copper-silver alloy would likely have too distinctive of a color difference for workers to not notice. My theory is that they had leftover bars of that copper-silver alloy used for nickels, and they used them for pennies instead. Although I’m not sure why they wouldn’t just make more nickels with the extra silver-copper alloy.
Good luck on the coin giveaway everybody!
Amazing. I am learning something new everyday. The hunt begins anew!
Always love these articles. So informative.
Half gram size larger penny hope I’d notice if just held it
Makes you wonder how many experimental coins have been struck in the early days of the Mint with little to no documentation. Some may have been “liberated” and have passed through the hands of thousands of people!
I just can’t look through all my wheat cents again. Good luck to the next guy.
that is crazy!
What an exciting find! Interested to find out if it will ever be determined for sure how this happened!
This coin is pretty cool!
Still don’t get how this combination could have occurred at the mint.???
would be awesome to win one….
Wow, another one to look for when I get my bags of pennies from the bank.
Wow!
That is an amazing looking coin, what a great find!
My sister just “cent” me an email about this penny! :D
Hard to believe it took so long to surface
WOW, an error, just being discovered… If it’s really an error as it could have been purposely minted that was… Is great to find after so many years. Sadly all our cents are being pulled from circulation by so many stores now, with none given out. Penny shortage, HAH, The Mint just ceased production, doesn’t mean there’s a shortage. To bad there will be less and less to search through these days.
the penny / cents have been taken for granted. The circulated penny will be missed but there are way to many in circulation to spend time looking for a needle in the haystack.
Interesting.
Could this be a counterfeit coin? Hard to believe it took this long to surface.
I’m on the lookout!!!
What a great article already checked mine no silver ugh
Thanks for the article. If I found this coin in my pocket, I would have thought it was counterfeit.
80 years later and still finding error coins. Extremely cool
80 years and still finding errors. Extremely Cool
I have so many cents to go through. I probably have nothing special but you never know!
My father worked for a power company during WW 2. He told of buss bars in a substation being made of silver to save copper. They were protected by 65,000 volts of electricity. He did not know if or when they were replaced.
I came across one of them silver penny.
I have to two 1943 collar one and the silver one
Where would you send coins to evaluate what’s it made of?
Wish I can find these types of gems
After all this time and just now found.
I have the 1945 Lincoln Cent Penny.