1947 Jefferson Nickel Possibly Struck On Silver Planchet

I highly doubt it's mercury...

I also highly doubt it's silver.

Most likely environmental damage caused by some sort of chemical exposure, either intentional or unintentional...produces the same result. A damaged coin worth a nickel.

Let me explain something. When metal detecting, the coins come up looking different depending upon the soil conditions. Nickels that I dug up at the beach on Long Island in NY looked like this.

Nickels that I dug up in PA often looked red or brown.

Nickels that I've dug up here in WA look dark grey.

The soil means everything.

The next point is that years ago, I worked for a mall, I saw thousands of nickels that came out of the pools and fountains, they also looked like this. The chemicals in the water would eat the zinc-plated cents and the nickels would be damaged by the chemicals in the water as well as the residue of the corroding cents.

In any case, the coin may not look like what you are used to seeing when metal detecting depending upon your location.

The coin is not silver, it is just discolored.

Thanks,
Bill

Got a metal detector? The detector will make a different sound for a copper nickel five cent than for a silver one because of the different ways that they affect the magnetic field lines around the coil.