2001P anom. How did this happen?

[Roller]

There is psd on this coin but I'm concerned about the dent on the reverse and corresponding bulge on the obverse. Any force sufficient to make the dent should have obliterated the roof design and the "rivulets" to the west of the bulge on the obverse appear to be die related. Any thoughts other than just PSD?

[duece2seven]

That's just weird. Looks like it literally sunk! I have no clue?

[jfines69]

To me it looks as if there was a cavity on the zinc planchet prior to plating... There is some distortion around the rim of the cavity (The NUM especially the west leg of M, the roof lines and the banners)... The obv appears to have been a strike thru that obliterated the bow tie and was enhanced due to the area on the rev!!!

[mikediamond]

Puzzling. The reciprocal pairing of an elevation on the obverse and an indentation on the reverse does suggest post-strike damage. However, the small spots of exposed zinc on the left border of the indentation suggests a natural defect. The patch of peculiar-looking ridges to the left of the elevation also doesn't look like post-strike damage. Perhaps this is a highly localized example of reciprocal convex-concave die deformation. I would certainly be interested in taking a closer look at it. -- Mike Diamond

[Roller]

Puzzling. The reciprocal pairing of an elevation on the obverse and an indentation on the reverse does suggest post-strike damage. However, the small spots of exposed zinc on the left border of the indentation suggests a natural defect. The patch of peculiar-looking ridges to the left of the elevation also doesn't look like post-strike damage. Perhaps this is a highly localized example of reciprocal convex-concave die deformation. I would certainly be interested in taking a closer look at it. -- Mike Diamond
I will send it to you next week.

[mikediamond]

Great. From the definitive nature of your response, I'll assume you still have my mailing address.

[Roller]

Yes, I have it.

[jfines69]

This is a cool development!!!

[mikediamond]

Even under a microscope, the defects are very puzzling. However, I lean toward post-strike damage. The indentation on the reverse face actually does not show any exposed zinc (the bright spots are crud). The borders of the indentation are too clearly defined to represent any kind of die deformation, in my opinion. The bottom of the letters NUM (of UNUM) slope down into the depression but don't show any change in shape or relief. I would have expected some sort of change if this was die deformation. Likewise, the decorative band on the Memorial shows no change in shape or relief where it cuts across the depression. While the odd ridges and valleys on the obverse face do look like a natural feature, they don't resemble any kind of die deformation I'm familiar with. They also don't look like die damage or a struck-through error. I have to assume they're impressions of a textured surface against which the cent was pressed.

I will continue to study the specimen to see if I can come up with any more telling observations.

[jfines69]

Thanks for the update Mike... From what you are saying could it be someones attempt at a counter stamp??? A poor one at that!!!

[mikediamond]

It could have been purely accidental. Or I could be entirely wrong and this is a new and unfamiliar error type that defies understanding. Like I say, I'll keep working on it.

[jfines69]

Thanks Mike!!!

[mikediamond]

I've spent some more time with this cent. I now notice that, on the reverse, the downward-pointing angle of the N of UNUM shows some burnishing and flattening where it is overlapped by the depression. That's consistent with post-strike damage. Also, the curve of the U shows subtle flattening where it intersects with the edge of the depression. That's also consistent with post-strike damage. So the preponderance of evidence continues to point to post-strike damage. The fact that the error makes little sense from a die failure perspective (or that of any other minting error) adds to the negative vibe that surrounds this coin. I'll mail this back to you, Roller, unless you'd like to donate it to my research collection. -- Mike

[Roller]

I've spent some more time with this cent. I now notice that, on the reverse, the downward-pointing angle of the N of UNUM shows some burnishing and flattening where it is overlapped by the depression. That's consistent with post-strike damage. Also, the curve of the U shows subtle flattening where it intersects with the edge of the depression. That's also consistent with post-strike damage. So the preponderance of evidence continues to point to post-strike damage. The fact that the error makes little sense from a die failure perspective (or that of any other minting error) adds to the negative vibe that surrounds this coin. I'll mail this back to you, Roller, unless you'd like to donate it to my research collection. -- Mike
You can keep it Mike.

[jfines69]

Cool... Now we now what caused this... Thanks for the update!!!

[mikediamond]

Thanks for generosity, Roller. It will enhance my collection of counterfeits and altered coins that I refer back to when I'm puzzling over a coin with an unfamiliar appearance.

[mikediamond]

A second cent with a somewhat similar error has led me to another hypothesis that may restore this coin to the ranks of genuine errors. It's possible that the elevation on the obverse is a die dent produced by a machine part (or something stuck to a machine part) that was moving in and out of the striking chamber. Maybe it was a piece of a broken die or collar that became embedded in a feeder. The machine part was out of the striking chamber when this coin was first struck. After this coin was struck, it stuck to the obverse (hammer) die. While that die and its adherent coin was retracted, the machine part returned to the exact same spot in the striking chamber. The hammer die descended once more, but during this strike, the minimum die clearance was greater than the thickness of the planchet. The only evidence of that second strike is the dimple on the reverse face, in the floor of which you see the first strike elements.

The one problem with this scenario is the lack of weakness in the first-strike elements in the floor of the depression. Given the depth of the dent in the opposite die, those elements should perhaps have been weakly struck. Then again, perhaps the depression in the obverse die face wasn't large enough to have any effect on the reverse design.

Like I said, I wouldn't have thought of this possibility if not for a second coin that had been in my collection for years and that I had never figured out. I fished it out today for an entirely different reason and spent a half hour racking my brain for an explanation. As I lay on my couch thinking, a workable scenario appeared in my mind.

I'll be continuing to study both coins and will write up my findings for Coin World. I'll keep you all in the loop.

[jfines69]

Thanks for the update Mike... Looking forward to your results!!!

[mikediamond]

Another point supporting this bizarre scenario is that the dimple on the reverse face doesn't seem deep enough to have caused the pimple on the obverse face.

[mustbebob]

There are not a lot of coins that grab my attention enough for me to remember it down the road like this one has. This is a great example of something that sticks in our head when we are not absolutely sure what caused the anomaly and also shows that minds can be changed after a while. I am intrigued for some reason. Keep us informed Mike. This is interesting.

[Roller]

A second cent with a somewhat similar error has led me to another hypothesis that may restore this coin to the ranks of genuine errors. It's possible that the elevation on the obverse is a die dent produced by a machine part (or something stuck to a machine part) that was moving in and out of the striking chamber. Maybe it was a piece of a broken die or collar that became embedded in a feeder. The machine part was out of the striking chamber when this coin was first struck. After this coin was struck, it stuck to the obverse (hammer) die. While that die and its adherent coin was retracted, the machine part returned to the exact same spot in the striking chamber. The hammer die descended once more, but during this strike, the minimum die clearance was greater than the thickness of the planchet. The only evidence of that second strike is the dimple on the reverse face, in the floor of which you see the first strike elements.

The one problem with this scenario is the lack of weakness in the first-strike elements in the floor of the depression. Given the depth of the dent in the opposite die, those elements should perhaps have been weakly struck. Then again, perhaps the depression wasn't large enough to have any effect on the reverse design.

Like I said, I wouldn't have thought of this possibility if not for a second coin that had been in my collection for years and that I had never figured out. I fished it out today for an entirely different reason and spent a half hour racking my brain for an explanation. As I lay on my couch thinking, a workable scenario appeared in my mind.

I'll be continuing to study both coins and will write up my findings for Coin World. I'll keep you all in the loop.
Having a hard time reconciling this latest scenario. If the object was large enough to not allow even a light contact of the anvil die (of which there is no evidence here), should the foreign object not have penetrated entirely through the planchet and should there not be a berm evident surrounding the perimeter of the crater on the reverse where the displaced material would have naturally flown?

[Roller]

Oops, should have looked at the pictures again before posting. There does appear to be a berm of sorts. Still, the penetration depth suggests that the object was not large enough to prevent all contact of the anvil die, if this did take place in the striking chamber.

[mikediamond]

There are other examples of "invisible strikes" involving circular or semi-circular foreign objects.

http://www.lincolncentforum.com/forum/attachment.php?attachmentid=110272&stc=1http://www.lincolncentforum.com/forum/attachment.php?attachmentid=110273&stc=1

That said, I'm now having doubts about that second specimen I mentioned. It may simply be a case of post-strike damage after all.

[mikediamond]

Now that the case for my second specimen is starting to collapse, I'm going to have to place the 2001 cent back in the suspense account. The scenario I came up, while theoretically possible, isn't sufficiently convincing without more evidence. There are too many improbable aspects -- a die dent caused by a pellet embedded in moving machine part that skips a strike and then returns to the exact same spot in the striking chamber beneath a newly-formed die cap is a bit too precious to take seriously, especially when it requires an invisible strike as well. I try to avoid special pleading, and this is a classic example of that debate strategy. Sorry to get everyone's hopes up, but I'm shelving my plans for an article.

[jfines69]

Mike,
Nothing wrong with with suspending an idea... One of the cool things about coins is that when new info comes up things can change... Just like RPMs that get delisted or Wavy Steps that were thought to be a DDR but turned out not to be... Thanks for the update!!!

[mikediamond]

By the way, there is at least one other nickel identical to the invisible strike nickel I posted above. Evidently the rounded pellet was stuck to the obverse die through at least two strikes.

[jfines69]

By the way, there is at least one other nickel identical to the invisible strike nickel I posted above. Evidently the rounded pellet was stuck to the obverse die through at least two strikes.
That's cool... No idea what year the 5c is but how long has it been known to exist???

[mikediamond]

I bought this specimen probably 10 years ago. The other specimen appeared in a Heritage auction about 5 years ago. There are other invisible strikes involving debris of one sort or another. But it's more common to find invisible strikes associated with partial brockages and indents. I've got many of those.