Unusual Canadian 25-cent strike-through

[SPP-Ottawa]

This one is odd. Very, very odd. This coin came from a freshly crack mint roll, acquired from a very reputable source, and this coin was in the middle of the roll. At first glance, I thought, 'oh, nice grade but it has a fingerprint'. Being a pure nickel coin, I tried a number of methods to remove the fingerprint, but upon close inspection, I realized that this fingerprint was not going to come off - ever. It was not toning from oils from the finger... the surface texture of the coin was not smooth inside the print, it was rough with brilliant surfaces in between. The reverse of this coin is perfectly fine.

I suspect that this was a greasy fingerprint on the die, then it struck a coin... oddest strikethrough I have ever seen...

Your thoughts??

[Jamez]

I have to wonder if this is a strike through of some type of cloth? I cant see how a fingerprint on a die would create this anomaly..

Other ideas?

[SPP-Ottawa]

I have to wonder if this is a strike through of some type of cloth? I cant see how a fingerprint on a die would create this anomaly..

Other ideas?

I thought about that too, like the fabric pattern of a glove or something, but then there would not be the bright (smooth) finish of the fields and devices in between the struck through elements.

A fingerprint was only a suggestion, mostly based on form analogy - because it looks just like one... I am at a loss to think of another similar type of object that would produce that pattern...

[diamond]

It's possible that someone's fingers were coated with a reactive substance when this coin was touched.

[SPP-Ottawa]

Remember, this is not a toning phenomenon, it actually occurs in the striking surface. Now, you are getting into my area of expertise, and I would argue against that happening.

Given that this coin is 100% nickel, it would have to be pretty nasty stuff out there on the Royal Canadian Mint's production floor. Pure nickel, in wrought hard form or annealed, is highly resistant to various reducing chemicals and is unexcelled in resistance to caustic alkalies at room temperature. For oxidation, the rate of attack is slow because of the formation of a thin protective film, usually a sulfate (which we don't see on this coin). Organic acids would not affect it. Pure nickel is not subject to corrosion in any of the chloride salts and has excellent resistance to all of the nonoxidizing halides. Pure nickel also has excellent resistance to neutral and alkaline salt solutions.

In fact, it would take some serious concentration of acid (hydrofluoric or phosphoric) or oxidizing alkaline chlorides to etch pure nickel like this - the damage to one's hand handling such stuff would be devastating. We use some nickel instruments when handling fluorine in our labs (HF is used to dissolve rocks for isotopic analysis), because when pure nickel is exposed to flourine, it forms a protective film of flouride on the surface of the metal.

The texture of the affected areas of this coin does not look like corrosion of nickel - it looks exactly like what I see with other strike through features on my nickel dollars. Any impurities I have seen with nickel composition Canadian coins (at least in the ones I have tested by XRF) usually are <1 percent iron or cobalt, which would still not cause a reactive agent to do this...

For now, Ockham's razor still applies here... I still think it is a strike-through, the question is what...

[diamond]

I've never seen a struck-through error with this appearance, but I guess there's a first time for everything.

[SPP-Ottawa]

I concur, and I am not completely sold on a strike-through - but that seems like the most logical explanation.

The coin now has a new home. For the princely sum of a pint of beer, I have traded the coin to a friend, who has an oddball/eclectic Canadian error collection of "what the heck is this" kind of coins (which includes TPG screw-ups). He absolutely loves the coin, as much as I love beer... so until something similar crosses our paths - it remains a solitary enigma...

Thanks for the input.

[coin-crazy]

Wow, another great coin!!

[numismanut]

Just a thought, but I'm considering the possibility that the uneven surface may have occurred earlier in the process. I have heard of lathe lines appearing at times, but perhaps this pattern is something that might happen with a CNC machine? I suppose the curvature of the lines could have resulted from a strike through of a fine cloth that got pulled in some direction more than others, results in the cloth becoming creased/temporarily malformed, but I can't quite figure this one out. Nice find though!