What is going on with this coin?? @@LOOOK...ERROR@@@@

Stork

Okay, just being silly because of how many error questions come up.

That said I am not sure what/how this came about. It's a tin coin and the striation oxidation is fairly typical.

And though I've seen a few flaws and blebs, never anything like this. Looks like a completely bubbled planchet. Is this a planchet thing? Post mint heat application? Environmental damage? I was fascinated by it and could not help buying it.

I posted it on an error forum too, but hoping a wider market could answer this.

detail with some photo tweaking

Kliao

This looks like some Lincoln zinc pennies because of the copper and zinc layers but this coin is all one metal......

I don’t really know...

WorldCoinsDmitry

It happens during the minting process when the planchets are not completely dried from preparation steps. The heated, expanding water is what causes these bubbles. Pretty commonly seen on coins of this type.

Stork

@WorldCoinsDmitry said:
It happens during the minting process when the planchets are not completely dried from preparation steps. The heated, expanding water is what causes these bubbles. Pretty commonly seen on coins of this type.

Just never seen one quite like this. It's going into my tiny Japanese error collection then. Wasn't sure if something so extensive might have been heat (presumably) added later. Cool beans...and I'm sure I over paid for it (even after negotiation...).

WorldCoinsDmitry

I found this past ebay listing that has what may be useful info: https://www.ebay.com.au/itm/BIZARRE-ERROR-Japan-1-Sen-1944-Trapped-AIR-BUBBLES-Tin-Zinc-UNC-WWII-Coin-/153425234180

Namvet69

Me thinks an improper alloy mix especially given the metal. Peace Roy

Sapyx

Tin is an interesting element. It is officially classified as "semi-metallic", along with several other elements that are tin's neighbours on the periodic table.

Tin has two commonly encountered "allotropes", or crystalline structures: alpha-tin, which is a gray, brittle semi-metal, and beta tin, which is the more familiar white metallic form. At ordinary room temperature, beta-tin is stable. However, if the temperature falls below 13.5 degrees Celsius (55.8 degrees F for the North Americans), beta-tin can start to spontaneously convert to alpha-tin.

Raising the temperature again will not convert the alpha-tin back to beta; the damage is irreversible unless the tin is melted down again. Spontaneous formation of alpha-tin on and in metallic tin objects is called "tin disease" or "tin pest".

I strongly suspect that this is what has happened here: bubbles of alpha-tin have formed inside the coin. The tin oxide on the surface of the coin has prevented the tin pest from breaking through the surface. This Wikipedia article has a picture of a tin medal with similar (though much larger) bubbles all over it.

The story that Napoleon's Army, retreating across Russia in midwinter, froze to death because the metallic tin buttons on their uniforms turned into alpha-tin and disintegrated, appears to be an urban myth. But is a convenient reminder to keep your tin coins nice and warm.

lordmarcovan

My guess would be "tin pest", and I was about to post that Wikipedia link, but I notice @sapyx beat me to it in the preceding post.

Stork

Thank you all! I did see the eBay descriptor and it seemed totally plausible, but I kept thinking there was potentially something else too. I may send it in for slabbing either here, ATS, or maybe even around the corner (that is ICG/ANACS) just to keep it housed and labeled in a way that is clear. In the meantime it's in my basement which is relatively temperature controlled, dehumidified, and in Intercept (either a box, baggie, or both for my better coins).