| Author |
 Replies: 13 / Views: 3,660 |
|
|
Valued Member
United States
142 Posts |
|
|
|
|
Pillar of the Community
 United States
5190 Posts |
|
|
Pillar of the Community
United States
1491 Posts |
It's oxidation of the edge of the pure copper core due to environmental exposure (e.g. moisture or chemical). Copper is a very reactive element and easily darkens.
|
|
Pillar of the Community
2145 Posts |
Quote:
oxidation of the edge of the pure copper core due to environmental exposure (e.g. moisture or chemical).  Sulphur will turn copper black. If exposed to heat that will also turn copper a dark color. Don't know where that quarter has been to pinpoint the real cause. |
|
Pillar of the Community
United States
5190 Posts |
I still don't understand why the Mint keeps minting quarters with a copper core. Why not switch to a pure nickel coin?
|
|
Bedrock of the Community
United States
62064 Posts |
Well, even nickels are not pure nickel. 75% copper 25% nickel.
|
|
Pillar of the Community
United States
1491 Posts |
@NumisEd
"I still don't understand why the Mint keeps minting quarters with a copper core. Why not switch to a pure nickel coin?"
Pure nickel is ferromagnetic. I believe that can mess up vending machines. Someone can correct me if I'm wrong on that.
|
|
Valued Member
 United States
142 Posts |
But all the way around the coin? I've been going through a bunch of quarters and haven't seen one like that.
|
|
Pillar of the Community
Canada
6244 Posts |
If you do a pure Ni coins you has to change all the chain. the nickel proprieties are different and react different with the exterior forces.
I will stay with the statement of Rothery. Seem to be affected by the Sulphur. Could be from environment or simply a touching cartoon or paper.
|
|
Pillar of the Community
United States
4963 Posts |
Nickel is more expensive than copper and would raise costs, even if just increased from 11.5% to 25%. You know the government doesn't like that.  As for the edge, sulfur is a possibility. Given how the rest of the coin is unaffected, though, I wouldn't rule out something more mundane; it looks a lot like Sharpie. |
|
Pillar of the Community
United States
5190 Posts |
Or do like the Canadians do and mint nickel plated steel coins.
|
|
Pillar of the Community
Canada
6244 Posts |
@NumisED yes could be an idea. Here in Canada costed 3/4 bill to adapt for steel production line. In states will cost what? And what they will do with the copper? sell at discount? They just up-grade the lines two years ago at a cost of 1 bill.
Edited by silviosi
05/01/2021 10:49 pm
|
|
Moderator
 United States
56855 Posts |
First, we are talking about the "edge" not the "rim". I think the coin was in a folder for a bit and that folder caused the color change. John1  |
|
Valued Member
United States
142 Posts |
Oh yea, dang it!! I also get those confused. Thanks John1..that makes perfect sense.
|
| |
Replies: 13 / Views: 3,660 |
|
Posted 05/01/2021 8:48 pm
