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 Replies: 114 / Views: 9,138 |
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Valued Member
United States
108 Posts |
I have this Lincoln VDB that is yellow - in person, it is even more yellow than in the photo. A month ago I had the coin scanned with a $75,000 XRF gun at the world's second largest brass recycling business. The results: 61.45% Cu, 14.57% Al, and 8.78% W (Tungsten). There are also residual amounts of other various elements, including Tin and Zinc. The results are legit, since the brass company lives and dies by this technology. A metallurgist attested to the veracity of the XRF scan. From research I have done, the mint has experimented with Copper/Aluminum alloys as early as 1865. Such allows were rejected because they corroded too easily. I haven't found any other evidence of further research in the early 20th century. That does not mean such research was not done. In 1910 the French patented a Copper/Aluminum planchet that included Manganese. Experiments were no doubt done prior to 1910, and coins of this alloy were produced beginning in 1920. The question is, what is this coin? I sent the coin to PCGS, together with the screen shot of the XRF, and a request for metallurgical analysis. The coin was returned as uncirculated/cleaned, and with no metallurgical analysis done. My guess is some drone on the assembly line gave their 10 seconds to certify the coin as such, and not much more. By the way, bronze cannot be cleaned to produce this color. So, this coloration is definitely not just a surface alteration thing. The metallurgist also said there is quite a bit of penetration with the XRF scan. More to come........  Edited by philoponus6
11/08/2022 6:15 pm
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Bedrock of the Community
United States
19110 Posts |
Was the coin placed in a PCGS holder? If so, photos of the holder (with coin) would be fun to see. Thanks.
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Bedrock of the Community
United States
94367 Posts |
Yes, please start with the holder.
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Moderator
 United States
15384 Posts |
 to the CCF Agree - please show the coin in the PCGS holder. Looking forward to whatever else you have to offer on this coin from a technical analysis perspective. |
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Pillar of the Community
United States
3207 Posts |
an accurate weight could be revealing
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Valued Member
 United States
108 Posts |
I subsequently sent the coin to NGC in the PCGS holder, requesting a minimum of DETAILS for cross over. I figured NGC would at least see that PCGS thought the coin was struck with a mint die. I also requested metallurgical analysis for their $75 fee. Today I read at NGC that the coin did not cross over, and it is in the mail. So, I assume I am getting the PCGS holder back. I will send a pic when it arrives. I am pretty sure my son weighed the coin at 3.1 grams.  Edited by philoponus6
11/08/2022 6:36 pm
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Pillar of the Community
Canada
5238 Posts |
I am sure that the analysis is correct. It is surprising that tungsten was used. I can't imagine that would be a useful or easy to work with metal for coinage purposes. But since it was a test piece, even unlikely possibilities would have been used.
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Valued Member
United States
108 Posts |
The Manganese that the French used in the 1910 patent reduced corrosiveness. I am not enough of a chemist to know how Tungsten would be useful.
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Valued Member
United States
108 Posts |
Here is the PCGS photo, without the holder. The photo darkened as I decreased detail to get the image uploaded.  Edited by philoponus6
11/08/2022 8:33 pm
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Moderator
United States
94665 Posts |
what is the full PCGS number? That number in the pic can't be found in the PCGS data base, probably need the prefix too.
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Valued Member
United States
108 Posts |
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Pillar of the Community
United States
4691 Posts |
Very unusual. I would think this alloy would have a high melting temperature and be very hard, so not easy to work with.
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Valued Member
United States
108 Posts |
The VDB was scanned in a mylar flip. I am not sure what effect that would have. I do know that Thermo Fisher tested one of their XRF guns on a PCGS holdered coin, and the effect was negligible. And, that still would not explain away the weird color.
If the alloy seems non-workable, then it would have chewed up dies, and likely is not a planchet used for a foreign coin.
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Bedrock of the Community
Australia
21786 Posts |
Australian Aluminum Bronze $1 and $2 coins have been issued into general circulation since 1984.
There has never been a corrosion problem.
Alloy:
92% copper
6% Aluminum
2% Nickel (for hardening the alloy)
They retain their golden yellow color, despite heavy wear.
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Valued Member
United States
108 Posts |
The corrosion problem I read about was with die trials with Indian cents. It may or may not have been a problem, but that was a reason given. I think it was something about changing color when held in a hand. There might well have been other impurities present that they could not control at the time. Edited by philoponus6
11/08/2022 9:59 pm
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Pillar of the Community
United States
3207 Posts |
AFAIK, non-destructive XRF reports primarily on the surface being scanned, which means if this coin is plated, the results may be deceptive
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Replies: 114 / Views: 9,138 |
Posted 11/08/2022 6:14 pm
