Joe has a coin that is made of bronze when it should be made of silver. Such coins are usually quite valuable, because they are errors committed at the mint, and yet out in circulation. Ninety-nine percent or more of minting errors are caught inside the mint, so the few that escape are valuable.
Mike Byers' book World's Greatest Mint Errors gives full explanations of these and other types of minting errors, as well as tables of typical values. Likewise, Ioannis Androulakis of fleur-de-coin.com, has a comprehensive write-up on errors. Joe, please read Ioannis' article to discern which type of error you have. In general, there are two such errors:
- wrong planchet errors
- off-metal errors
which are similar but not identical. However, plated coins, which are described on this CoinQuest page are usually damaged coins and are not worth anything.
CoinQuest thanks fleur-de-coin for use of their coin image.
The table at the end of Mike Byer's chapter on planchet errors gives some typical values. Here are highlights of that table. You can see there are wide variations, so a precise value requires a precise, in-person, evaluation.
- Washington quarter struck on nickel planchet: $200 US dollars fully uncirculated
- Buffalo nickel struck on cent planchet: $2000 circulated, $6000 uncirculated
- Lincoln wheat cent struck on dime planchet: $500 circulated
- Indian cent struck on non-US plachet: $5000 uncirculated
- Roosevelt dime struck on non-US planchet: $2000 circulated
- Post-1964 Lincoln cent struck on dime planchet: $200 uncirculated