Swirly patina or copper?

[Snee]

I pulled this 1919S penny out of circulation today in penny rolls! The thing is, what's the deal with the swirliness? It reminds me of marble rye bread or something. It's on the obverse, reverse, and also the rim. Is this some kind of patina, or is it just some weird copper thing...what?

 

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[JakePhelps]

Looks like a strange patina or stain, copper doesnt normally look that way. Nice find by the way!

 

[Klaatu]

My guess is someone cleaned the cent with a harsh cleaner (e.g., brass or copper cleaner) before it ended back up in circulation. Once the outer layer of copper (actually bronze) is gone the coin may tarnish rapidly with some wild colors. (I should know; I cleaned a few cents in my younger days before I learned that killed their numismatic value).

 

[EDDE]

smoke damage from a fire or exposure to smoke/heat in some shape or form

 

[Jeffro]

I would second that- looks like probably a fire.