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 Replies: 11 / Views: 1,232 |
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Pillar of the Community
Russian Federation
1557 Posts |
Looking through online auctions, I came across this coin in 2 kopecks 1842. It can be seen that it is all corroded, but I am interested in what will become of it in 10, 30, 50, 100 years. It's just going to turn into a black circle of metal, right?   |
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Pillar of the Community
United States
634 Posts |
Corrosion is a chemical process involving contact with water, soil, acids, alkalis, or contaminants in the air. If a coin is protected from such contact, as yours is in a holder, it should retain essentially the same condition.
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Moderator
 United States
34397 Posts |
@slerk, exactly what @seek said. I have copper alloy coins more than 1000 years older than this one that aren't yet corroded into nothing.
"If you climb a good tree, you get a push."
-----Ghanaian proverb
"The danger we all now face is distinguishing between what is authentic and what is performed."
-----King Adz
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Pillar of the Community
 United States
7936 Posts |
At the age of 180, it is already a "black circle of metal" to perhaps 75% extent, with some coppery colored highlights on the devices.  As others have said, I do not think this will change in the next 30 years. If I wanted this coin in my collection, and the price was good, I would buy it. |
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Moderator
Australia
16816 Posts |
This coin is essentially pure copper. When copper corrodes, it turns green. The "contagious" form of copper corrosion, known as verdigris or bronze disease, is typically page greenish-blue in colour and very dusty or powdery in appearance. The stable, non-contagious form of corrosion, or "patina", is typically dark green. I'm not seeing either of those colours here on this coin. So what you are seeing here isn't corrosion, directly. It's the pits left behind on the bare metal once all the corrosion by-products been chemically or electrolytically removed. The metal left behind after such treatment is normally bright pink or orange in colour; the dark colour on this coin tells me that this cleaning happened some time ago; either that, or it has been artificially induced with a copper darkener. If that's in a TPG slab, we can probably rule out artificial darkening since they test for that kind of thing. As such, this coin is no more prone to further corrosion than a normal uncorroded pure copper coin. If you buried it back in the ground, or left it outside exposed to the sun, snow and rain, sure it'll corrode - but so will any other piece of copper, and at pretty much the same rate. Don't say "infinitely" when you mean "very"; otherwise, you'll have no word left when you want to talk about something really infinite. - C. S. Lewis
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Pillar of the Community
 Russian Federation
1557 Posts |
Quote:
as yours is in a holder As I wrote above, the coin is not mine. I saw her on one of the online sites for the sale of things. Sap, Thank you for your detailed answer. This coin was put up for auction and went for a small price, I didn't even bid because I considered the coins with corrosion dead, especially copper and especially so old.  |
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Pillar of the Community
Russian Federation
1557 Posts |
So, after all, I can buy coins with corrosion and have them in your collection? If she is in TPG, does that mean she is protected and she will definitely not get worse ? |
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Moderator
Australia
16816 Posts |
It shouldn't get worse, or at least, won't get worse at a faster rate than an uncorroded coin. The TPGs won't slab anything with active corrosion that they believe might get worse.
Don't say "infinitely" when you mean "very"; otherwise, you'll have no word left when you want to talk about something really infinite. - C. S. Lewis
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Pillar of the Community
United States
7936 Posts |
I bought this on purpose.  Slabbed by ANACS as "VF Corroded" This type is rarely found without "corrosion" and I thought the uniform patina was attractive. One of only five slabbed coins in my collection. As pointed out by Sap, greenish patina (carbonate, I think). Brownish-black patina is copper oxide. Edited by tdziemia
08/09/2022 10:17 am
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Pillar of the Community
Russian Federation
5172 Posts |
The OP coin is probably a metal detecting find that had been cleaned (chemically or electrolytically) to remove dirt and (some of the) patina. TBH it seems to have been actually a fairly mild cleaning, as those things go, but of course the environmental corrosion from 150+ years underground is irreversible.
I agree that if you don't put this coin in a damp environment it probably won't corrode any further; there would have been more risk if there were still green spots, indicating possible active corrosion nuclei.
I'm not sure why anyone bothered to slab this. I estimate a value of $5-10 for this date in this condition - maybe more outside Russia. I wonder what was the "small price" that it sold for.
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Pillar of the Community
Russian Federation
1557 Posts |
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The OP coin is probably a metal detecting find that had been cleaned Please remind me what OP is. I need to write this term down in my notebook. Quote:
I'm not sure why anyone bothered to slab this. I estimate a value of $5-10 for this date in this condition - maybe more outside Russia. I wonder what was the "small price" that it sold for. I have seen this coin on 2 sites. Initially, it was sold at auction for 900rub(14,83$), later it was resold for 700rub(11,54$). |
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Pillar of the Community
Russian Federation
5172 Posts |
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Please remind me what OP is. I need to write this term down in my notebook. OP means Original Post (and/or Original Poster), AFAIK. Basically the starting post in the thread. |
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Replies: 11 / Views: 1,232 |
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Posted 08/08/2022 1:43 pm
