Help with this 1918 S Buffalo nickel 1 1

[Axle Tuggin]

I have had this coin for a few years now and I can't seem to find any information regarding its color anywhere. I looks to be 100% copper. The third picture shows it next to a penny for comparison. Sorry my photos are not the best but it even shows signs of a reddish patina that can't be seen in the photos and not a single spot of silver color anywhere on the coin.  Thank you in advance for the time.

[Greenstang]

Welcome to the Chat Board

It appears to be environmental toning, possibly it was buried for awhile.  
Weigh it to two decimal points.

[Coinbuf]

Looks like dye or paint as the rims and some of the high points are more nickel color.

[Mike Meenderink]

This coin has been either buried or in moist soils or in brackish water at some point. The soil or brackish water can easily oxidize a nickel coin brownish red by sulfur or other contamination. A 1918 Buffalo Nickel is 75% copper and 25% nickel. Copper is much more reactive than nickel. The coin has exchanged the copper by the process of oxidation bringing it all to the surface of the coin. Its ruined. Not worth more than $3.00 if that. It's a good example of an oxidized nickel for teaching.  Cheers.

Edited May 25 by Mike Meenderink