Error or PMD?

Here you go.

 

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That has the look of a strong acid, my money is on that.

PS: Let's see the reverse.

 

That's called a Whizzed Surface (Whizzing).
I learned that terminology from Mint Error expert @Fred Weinberg

Not a mint error of any kind unfortunately. It's an alteration done after it left the US Mint.

 

Damage.

 

Could have been an eraser.

 

Definitely damaged

 

Freshly "Whizzed" clean on an electric wire brush. PMD.
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