I've just renovated a 1918G coin that was completely covered in rust and almost unrecognisable as a coin to find what appears to be a copper based metal.
Yours is definitely not copper. Your cleaning process may have discolored it. Why would anyone zinc coat copper? Zinc was used to protect the underlying iron if the coin got scratched but is much less corrosion resistant than copper.
I'm no metallurgist, but I do have a Master of Science Degree in Botanical Horticulture so I understand chemical composition. I believe Iron does not contain Copper, so why does this coin show a copper colour as a base metal?
Maybe someone who understands chemistry better than me can help answer this question?
I'm no metallurgist, but I do have a Master of Science Degree in Botanical Horticulture so I understand chemical composition. I believe Iron does not contain Copper, so why does this coin show a copper colour as a base metal?
Maybe someone who understands chemistry better than me can help answer this question?
You yourself proved it wasn't copper when you determined it was magnetic. There are a lot of red things in this world that aren't copper. What color is iron oxide (i.e. rust)?
You say that the coin was covered in rust and that you used vinegar to clean it.
As a chemist, I would bet that you generated some iron (III) acetate on the surface of the coin during the cleaning process. Vinegar is acetic acid, and since the coin was very rusty, there were many ferric iron ions around, so you made some iron (III) acetate which is brownish-red (or reddish-brown, depending upon your preference). It is possible/likely that some of the iron (III) acetate adhered to (or coated) the surface of the coin.
I've just renovated a 1918G coin that was completely covered in rust and almost unrecognisable as a coin to find what appears to be a copper based metal.
