Old Spanish Copper Cob

[TheCaribbeanDigger]

Hi good folks of TN! I found this "coppa" cob on a beach in Puerto Rico. Can somebody tell me or know from what year it is? It's a little bigger than a US dime.

 

[TheCaribbeanDigger]

Thinking, can silver tarnish to a green color? Someone told me once that silver could go green, depending on the alloy of the coin. Just curious...

 

[Mackaydon]

Silver tarnishes to silver oxide which is black in color.
The green represents copper.
You may have a Spanish maravedi coin.
Don....