First background, I'm a cashier... I hate it... it sucks...

Now to the story, today I ordered quarters for my register since I was completely out. When they finally arrived I found a gold quarter mixed in... yes... gold. I don't know yet if it is real gold but it is a real quarter. Naturally, I like the old and the rare so I swapped it out for a quarter in my pocket to keep. I seriously doubt it's made of gold, but it looks like it has either been discolored by some chemical (would be one nasty chemical IMO), or it has been gold plated for some reason.

Anyone ever hear of something like this before?