1971-S Penny, Silver In Color!?

As CrazyB0 said, the increase would be very slight, and it was probably a bit underweight to begin with.

Thanks for all the help guys, what a great forum! Here is a side view which I should have included originally. The sides all look original copper in color, as in it doesn't appear to have worn through a coating to reveal copper. The front and back of the coin don't seem to show any copper under or at points of wear, just a silvery color with some darker/wear marks like on Lincoln's shoulder. If it was coated wouldn't the wear and finish be the same on the side wall of the coin as the front and back?

Yes potentially, although areas can be masked off from the plating if desired. Also, just a head's up that back in the "old days" one way to make a cent silver-colored was to rub it with Mercury. I'm not saying that this was done to your specific coin, but this early CCF thread talks about this possibility:

http://goccf.com/t/96160

That's pretty cool, BadThad. Does that apply to the copper-plated Zincolns too or do you just have the 2007 in your photo for color comparison? I wouldn't think Zincolns would hold up to heat as well as 95% copper.

Yes. But the remaining 5% is zinc.

(Before 1962 the 5% was a mixture of tin and zinc.)

I didn't realize that little amount of zinc could do the trick. Learn something new.

I managed to turn a 1975 penny goldish colored by soaking it in a water/white vinegar/salt/baking soda/ solution while cleaning it with a rag. I came out shiny, clean and gold with kinda pretty clouds of layered amber colors.