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1966 Washington Quarter Clamshell Separation ?

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 Posted 08/05/2022  7:01 pm  Show Profile   Bookmark this reply Add Adam_E to your friends list
This coin was buried in acidic soil for some time. The acid ate away at the copper more than it did the nickel, so the copper core receded into the coin quicker than the nickel did.
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 Posted 08/05/2022  8:34 pm  Show Profile   Bookmark this reply Add oddguy to your friends list
i agree with some sort of acid being in ground or type material.
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 Posted 08/05/2022  8:36 pm  Show Profile   Bookmark this reply Add coop to your friends list
The clamshells look more like these coins:
1966-Washington-Quarter-Clamshell-Separation-?
1966-Washington-Quarter-Clamshell-Separation-?
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 Posted 08/05/2022  9:09 pm  Show Profile   Bookmark this reply Add silviosi to your friends list
I do not see clam shell effect here. What I see it is a coin which liked to take a acid bath. Sorry, not clam shell.
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 Posted 08/06/2022  05:20 am  Show Profile   Bookmark this reply Add John1 to your friends list
I think it is acid damage.
John1
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 Posted 08/06/2022  10:28 am  Show Profile   Bookmark this reply Add Kopper Ken to your friends list
Nice discussion coin...would acid dissolve copper more efficiently than CN...why would the acid dissolve the copper right in the middle? Any chemists out there?

KK
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 Posted 08/06/2022  2:13 pm  Show Profile   Bookmark this reply Add Dearborn to your friends list
oh, ok, I see it better in the daylight. Not a partial collar. It is an acid dipped quarter.
The copper core is a softer metal than the copper/nickel cladding and will dissolve quicker than the cladding.
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 Posted 08/06/2022  4:05 pm  Show Profile   Bookmark this reply Add silviosi to your friends list
To answer at the KEN question: The cooper dissolve in nitric acid (HNO3) acid solute. But this acid is not easy to have or be find in the nature. When I see the coins like this I go and the studies confirm that the coins was in contact with citric acid.

What happened: The core cooper is in fact an alloy of Cu-Zn. The citric acid dissolve the zinc not the cooper and the clad will be slow corroded.

Manny other reaction could be possible with different bases, acids, in special mild acids. If the coin was in one lab or goldsmith plant could has interferences with potassium chloride or cyan hydrate of potassium.
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 Posted 08/06/2022  7:41 pm  Show Profile   Bookmark this reply Add Petespockets55 to your friends list
I'm with Dearborn about this being a tilted partial collar strike as well as having been in a caustic environment (acidic).
Take a look at OP's images 3 & 4.
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We need to consume them regularly to thrive and grow.
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 Posted 08/06/2022  8:16 pm  Show Profile   Bookmark this reply Add silviosi to your friends list
@Pete: with your permission please. We employ the word caustic for corrosive reactions. Is a popular form to say corrosive environment. The word caustic referee just and limited to organic tissues and not to metals. Hope one day in the future the young generations will be more precise then us now.
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 Posted 08/06/2022  9:43 pm  Show Profile   Bookmark this reply Add Petespockets55 to your friends list
That's interesting Silviosi.

I didn't realize caustic was a term only for organic tissue but it makes sense.
Now I just have to reprogram my POM. (Petespockets Old Memory. )
Words of encouragement are one of the major food groups.
We need to consume them regularly to thrive and grow.
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 Posted 08/06/2022  10:25 pm  Show Profile   Bookmark this reply Add silviosi to your friends list
in my case I will say SOSM (Silvio Old Stupid Memory). Stupid come from all crazy thinks I do or test. Few days ago I do 'it involuntary Trinitroglycerin and go to smoke near my cigar LOL

I neutralized and destroyed now, but I was not far to put 6 neighbor to sleep in the park LOL.
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 Posted 08/07/2022  07:49 am  Show Profile   Bookmark this reply Add Petespockets55 to your friends list
After smoking near the nitroglycerin, did you make it onto the local news channel? LOL
Words of encouragement are one of the major food groups.
We need to consume them regularly to thrive and grow.
Edited by Petespockets55
08/07/2022 2:05 pm
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 Posted 08/07/2022  2:33 pm  Show Profile   Bookmark this reply Add Kopper Ken to your friends list
Thanks Silviosi...always interesting.

KK
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