Occluded Gas Bubble Pitting? Yes or No and... why or why not you attribute the error. 1 1

[Mike Meenderink]

Look at the coin below. Determine if this is or is not an occluded gas bubble pitting mint error and how you came to your conclusion. If you think its not an occluded gas error then suggest your best attribution. This will help us all understand and learn about strange coin errors that are not widely known. Cheers.

In my opinion it is Occluded Gas Pitting obv/rev with tarnishing and post mint zinc deterioration in those affected areas. You?

[bsshog40]

Looks like heat damage to me. 

[Sandon]

   It's most likely damage that removed the copper plating, and the underlying zinc that had been exposed then corroded. It could also be plating bubbles that contained gasses that caused both the copper plating and the zinc to corrode. There's no way to tell. In either case, the coin would be highly undesirable to me as a collector.  I wouldn't hesitate to spend it!

[RWB]

On 1/16/2023 at 11:28 PM, Mike Meenderink said:

an occluded gas bubble pitting mint error

Please explain what you mean by the above.....

[Coinbuf]

On 1/16/2023 at 9:28 PM, Mike Meenderink said:

Look at the coin below. Determine if this is or is not an occluded gas bubble pitting mint error and how you came to your conclusion. If you think its not an occluded gas error then suggest your best attribution. This will help us all understand and learn about strange coin errors that are not widely known. Cheers.

In my opinion it is Occluded Gas Pitting obv/rev with tarnishing and post mint zinc deterioration in those affected areas. You?

You are 100% wrong, occluded gas errors only happen on solid alloy coins not on zinc core plated coins as is the case with the 1990 cent you posted.   Common plating blisters that popped and now you have zinc rot, not an error just a spender.

 

On 1/17/2023 at 10:29 AM, RWB said:

Please explain what you mean by the above.....

From a coin world article written by Mike Diamond:

"An “occluded” gas bubble is simply one whose roof has remained intact instead of rupturing from the internal pressure. If the roof is of sufficient thickness, it could conceivably resist pressure from a toothpick.

The occluded gas bubble hypothesis is supported by a microscopic surface texture that is identical to the surrounding field. Even microscopic die flow lines continue across the two bulges without interruption. This supports the idea that the die face was intact and undisturbed when the coin was struck.

Occluded gas bubbles are restricted to solid-alloy coins and should be distinguished from plating blisters that form in copper-plated zinc cents. Blistered plating occurs when there is a poor bond between the copper plating and the zinc core. Heat generated by the strike causes gas expansion beneath the plating, pushing it up."

Here is a link to that article if you wish to read all of it.   Coin world article

[Greenstang]

I was just starting to reply when I saw that Coinbuf beat me to so I will just say that I agree with his statement.

An occulated gas bubble only occurs on solid-alloy coins such as  pre 1982 solid copper cents.

Edited January 18, 2023 by Greenstang

[RWB]

OK. Thanks for the explanations. So the OP's coin doesn't fit the definition....

Gas bubbles and various inclusions were well known to mint officers in the 19th/20th centuries. Here's one reply from 1880:

Samuel P Duffield, M.D. PhD
Dearbornville, Mich
September 27, 1880
Sir:
I have received your letter of the 24th instant, transmitting a quarter dollar supposed to be counterfeit.
The coin is genuine. The want of sonority is caused by a flaw or split in the piece which I have further opened.
A flaw of this character is occasioned by a minute air bubble formed in the ingot in casting, and subsequently spread out in the rolling process. The piece is herewith returned.
Very respectfully,
R. E. Preston,
Acting Director

Edited January 17, 2023 by RWB

[VKurtB]

I’ve had occluded gas bubbles from time to time. Eventually, they can pretty much clear a room. 

[RWB]

Keep some long matches handy...they can prevent gas buildup.

[VKurtB]

On 1/17/2023 at 3:09 PM, RWB said:

Keep some long matches handy...they can prevent gas buildup.

Matches used to be ubiquitous. Now, you really have to look for them.