Grey Penny.

The basic experiment has probably been around for decades. I remember it from the 70s. I have no idea when it first appeared in a manual, or which one. I can't even remember the college text I used to teach intro chem in '67, so I sure can't remember the lab manual. I think it still appears in some current ones, or is passed around by teacher forums. They indicate it can be used for 3rd grade and up ( with adult supervision).
http://chemistry.about.com/od/chemistryhowtoguide/a/goldsilverpenny.htm

 

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I think it had to have started after 1982...

 

I guess the only way to really know if it's made from a solid alloy ( pre-'82) and not just a grey coating from a chem-test is to operate on it.

Either find an area to drill or slice off a small piece to see if it's still copper inside the core. That would rule out the chem-test.

I have a '78 that has the same luster as a nickel, and on the edge I filed down a very small portion and underneath was more zinc colored metal.

I went deep enough to make a difference to rule out just a zinc coating.

P.S. The Zinc or what appeared to be Zinc under the surface shined with more brilliance then the surface.

 

Here's the same " Cent" as the close up of the filed edge above around a few nickels for comaprison. This wasn't found in a fire. It was found in a bank roll.

 

What about the possiblity of a Improper Alloy Mix?.. alittle too much zinc and tin in the batch intended to me 95% copper?

 

Why?

 

I also have a 1989 penny just like the ones being talked about and I have had it for approx. 3-4 yearsand I live in Reno Nevada so maybe there is a better story about unique coin and the distance between them?