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 Replies: 15 / Views: 1,212 |
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Valued Member
United States
127 Posts |
Came across this spectacular sample while perusing a well-known online auction platform this morning. (I am not advertising. Just posting a coin I find numismatically and aesthetically interesting.) Germany 1923E PF68 UCAM 3 Mark (Population = 3 in 68\12 total from 61 to 70) Composition = Aluminum (which at that time was more valuable than silver)     Edited by TheColorofMoney
08/14/2022 07:17 am
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Bedrock of the Community
United States
94367 Posts |
Impressive!  |
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Pillar of the Community
Russian Federation
1557 Posts |
You know, not so long ago I realized for myself that collecting world Proof coins is a great idea for a collection. Sometimes the prices are not so high and you can easily afford to buy coins from Switzerland or France for a couple of dollars.
If the price of this German coin is not very high and you can afford it, then why not. A nice coin of Germany during the Weimar Republic.
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Valued Member
 United States
127 Posts |
Slerk
$650 USD
Just imagine the equivalent US coin minted in 1923. It would be priced at 6 figures.
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Valued Member
Germany
312 Posts |
Very attractive.
I have no experience with aluminum coins, but I know that aluminum always forms an oxide layer in air. Does this layer not hamper luster and reflectiveness? Does not seem to be the case, I can hardly imagine this coin being kept under nitrogen for almost 100 years.
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Valued Member
United States
127 Posts |
HP2001PH
There is something like 20 all said in high grade in the NGC registry. I have not checked the PCGS registry.
Evidently if stored just right, then aluminum can maintain a spectacular condition even over the long term. I too am surprised. I would think that even the typical ambient atmosphere would be sufficient to corrode or oxidize or otherwise degrade the aluminum proof surface to an unacceptable level.
Edited by TheColorofMoney
08/14/2022 07:24 am
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Pillar of the Community
Russian Federation
1557 Posts |
Quote:
but I know that aluminum always forms an oxide layer in air. I bought this coin today. Are these oxides ? Aluminum coin.  Edited by Slerk
08/14/2022 4:44 pm
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CCF Master Historian of USA Commemoratives
 United States
12269 Posts |
Quote:
Germany 1923E PF68 UCAM 3 Mark
Composition = Aluminum (which at that time was more valuable than silver) I'm aware of aluminum being considered a precious metal and having a higher price vs. gold and silver in the late 1800s, but I thought by the 1920s new ways for mass extraction of aluminum from ore had been successful for decades and aluminum was no longer an expensive, precious metal. I though it was a lower-cost industrial product by then and had even been used for military materiel in World War I. Am I missing something? Collecting history one coin or medal at a time! (c) commems. All rights reserved.
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Pillar of the Community
United States
2954 Posts |
Fascinating coin there  ! I have a few of this type in my collection. My earliest aluminum coin is from 1908, and I know how hard it is to find nicely preserved coins made from that metal pre WW2. Germany must have had plenty of aluminum to go around back then for all the coins made from it. To Slerk: I do think some aluminum coins can develope a film of oxide on them, sometimes it probably helps, sometimes not, depending on where that coin went after it got minted. Commems thinking sounds about right to me at least...  |
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Valued Member
Germany
312 Posts |
Slerk, I am not sure.
I did a bit of research and found that Al oxidizes within hours in air (always), but that the layer is only a few nm thick. I guess it is invisible.
The thin layer then prevents further oxidization almost totally. It happens, but at a super slow scale, since the probability of further oxygen molecules to pass the layer by diffusion is very low. It is a bit temperature dependent though.
Edited by HP2001PH
08/15/2022 01:21 am
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Valued Member
United States
127 Posts |
Commems
You are correct. The Bayer process, developed in 1888, eventually removed aluminum as a precious metal.
Thank you for the historical correction.
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Pillar of the Community
Russian Federation
1557 Posts |
Quote:
Slerk, I am not sure.
I did a bit of research and found that Al oxidizes within hours in air (always), but that the layer is only a few nm thick. I guess it is invisible.
The thin layer then prevents further oxidization almost totally. It happens, but at a super slow scale, since the probability of further oxygen molecules to pass the layer by diffusion is very low. It is a bit temperature dependent though. Thanks for the explanation. My coin looks definitely UNC, it even has a glint of aluminum on it. But these spots. Most likely, the problem is the incorrect storage of the coin. At the dealer, she was lying in a cheap album + the sun could harm her a little |
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Pillar of the Community
 United States
7940 Posts |
Quote:
Commems
You are correct. The Bayer process, developed in 1888, eventually removed aluminum as a precious metal.
Thank you for the historical correction. A correction to the correction: By 1888 the predecessor company of Alcoa had already built a plant in Pittsburgh and was making aluminum based on the 1886 discovery of American chemist Charles Hall.  |
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Valued Member
United States
127 Posts |
Quote:
A correction to the correction: By 1888 the predecessor company of Alcoa had already built a plant in Pittsburgh and was making aluminum based on the 1886 discovery of American chemist Charles Hall.
There's a million things to know about history. Fun stuff. |
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Pillar of the Community
United States
7940 Posts |
I have an unfair advantage in this case... I used to teach chemistry in Ohio, and Charles Hall, the American inventor of the process to purify aluminum which bears his name, also happened to be from Ohio.
It's hard to think of a more important innovation in the field of metallurgy in the last 150 years (but I hope someone will challenge that assertion)
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Valued Member
Germany
312 Posts |
Actually modern Aluminum production uses both the Bayer and the Hall-Heroult processes (parallel invention in the US and France). For cost-effective production both processes are needed.
Edited by HP2001PH
08/18/2022 06:24 am
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Replies: 15 / Views: 1,212 |
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Posted 08/13/2022 12:01 pm
