What type of corrosion 1 1

[Hoghead515]

What type of corrosion usually causes the inner copper layer to be eaten out of a quarter? Ive seen them like this before and was just curious. Do you reckon it was exposed to some type of acid? I googled it and couldnt find any results. I know its not worth anything. Just a badly damaged quarter. Just wondering what eats up the copper inside. Thank you for any feedback. 

[J P M]

It looks like it has been sitting at the bottom of the swimming pool for 40 years.

[Coinbuf]

Acid will do that.   And not the kind some people consume. 

[Hoghead515]

Thank you all. Acid was one of the first things I was thinking of. I was thinking it may have laid in some kind a corrosive liquid for quite a long time. Something thats more corrosive to copper than nickel. 

[VKurtB]

On 1/3/2023 at 7:00 PM, Hoghead515 said:

Thank you all. Acid was one of the first things I was thinking of. I was thinking it may have laid in some kind a corrosive liquid for quite a long time. Something thats more corrosive to copper than nickel. 

Most of the commonly known  acids will do precisely this, given enough time.