is this a mint error?

I have a strange 1977 quarter. On the back it appears to have a 1/4 inch bobble where the joint in the eagles right wing is. The bobble can also be noticed on the front of the coin as well but is not as large.

The coin itself is very dirty but the dirts rubbed off of the high points and bobble making it very noticeable.

Hopefully I’ll be able to scan it and post a picture of it some time this week.

I’ve looked around on the web but couldn’t find anything like this.

Have any of you seen anything like this and do you think it could me an error from the mint?

 

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Hello and welcome to the forum! There's better chance to get help with a pic...sometimes is very hard to imagine the error just by the description, unless is a very common one.

Ivan

 

Ok here’s picture of the coin. I know it’s a poor one sorry about that. I hope it can still help.

picture1

And here I circled the bubble like thing.

picture2


I didn’t scan the front because you can’t really see the bubble there.


I’ll wanted to get a better picture but with this weather I can’t get to a better scanner.

 

Thanks GDJMSP. I searched for it and found all I need to know. Most of it was typed by you so thanks for that to.

Now I’m off to put my first error coin in a place of its own in my collection.

 

The vast majority of these "bubbles" are created outside the mint, evidently by applying a source of heat, such as a blowtorch flame. As a result, almost all of these coins are discolored and/or have a roughened surface. As a matter of fact, I have never seen a genuine example.

 

Was going to say heat too...but you beat me to it

Just looking at your coin scan/picture, I would guess it had been in, or near, a fire. Can't say that for certain as coins come in contact with all kinds of chemicals and environments that change their color, but black with bubbles is a pretty good indicator IMHO

 

Actually the black color is probably from spending years in a toolbox with oils and grease. Still very possible it could have gotten burned in the garage as well.

Any way I’ll be getting back into my collection this weekend and look for more sings of burning.

I’ll let you know what I find.

 

<It is the result of gasses being trapped between the clad layers which expand and create the bubble when the coin is struck.>
These bubbles are not created when the coin is struck. Yes there is gas trapped between the layers but gas in compressable an even if there was a bubble in the planchet the force of the strike would simply compress the gas and give you a flat surface. Some would suggest that the heat created from the striking causes the gas to expand and create the bubble post strike. Well even though the mtal of the coin "flows" during the strike, it is considered a cold flow or working of the metal. Yes the coins come out of the press hot. But they are still at a temperatue LESS than 200 degrees Farenheit and at those temperatures the coppernickel clad layer is for all pratical purposes just as ridgid as it is at room tmperature. That tiny bit of gas inside has no chance of deforming that cold metal to create a bubble in the coins surface.

The only way it will form a buuble is throughthe application of intense heat which will incease the pressure of the gas. Even then it won't form a bubble until the coppernickel starts to approach its melting point which is over 3000 degrees.

 

Thanks for the help.

After looking over it better all I could find was that the bubble formed at least after being struck.
I’ll assume it happened after leaving the mint.

Also I just thought of something.

I don’t know much about minting coins but could it be possible that something harder could be molded into the blank creating the same effect?

 

If somehow you did manage to get some hard "lump" trapped between the layers when the initial ingot was created it would either be crushed and/or poked through the outer layers during the rolling out of the ingot to the thickness of the planchets.

Think about it. The "bubble" seen in the coin is thicker than the original planchet. If the trappd object was crushable the rollers would have smashed it flat and it would not show as a bubble on the finished coin. If it isn't crushable it either won't go through the rollers (creating severe damage to the strip), or does go through but cause damage to the rollers and poke through the outer layers of the coin exposing the object.

Take a rock and put it in a lump of clay and then try and roll it out to a thicknes less than that of the rock and you will see what I mean. (Play-Doh is great for doing experiments like this. It is also good for examining how repunchings, doubled dies, and other forms of errors are created.)

 

Roller issues set aside, if a "harder", slightly thicker bit of metal made it into a planchet and met with a die, I'd imagine that the die details would only be on the bubble, not making it to the rest of the planchet.

 

If the "harder" piece is hard enough not to be flattened by the strike it would also most likely be hard enough to cause damage to the surfaces of the die as well. This would leave evidence on every coinstruck after that time. As an example, look at the spiked chin half cents. They were created by the dies coming together on a planchet that had a small bolt laying on it. The head of the bolt created the spike at the chin and a small one by the mouth. It also cut curved lines into the surface of the obverse die from the treads of the bolt. The spike is clear on all subsequent coins but the thread marks are usuaily only seen on better grade coins.