During the coin minting process, errors can occur at every step in the process. Often these error coins make it all the way to circulation where a person may be lucky enough to find one in their spare change.
There are several ways in which an error coin is produced. Most error coins are the result of an accident or an equipment malfunction. Errors also occur when the striking equipment begins to deteriorate, indicating it needs to be replaced. Finally, errors can occur if mint personnel make slight changes to the process in hopes of improving a coins quality. Sometimes this works and other times it fails, thus creating an error coin.
Here is a list of common errors:
- Blank Planchet: Occurs after a coin blank has been turned into a planchet, but some how skips the striking process, resulting in a coin with no design.
- Clipped Planchet: If the metal strip that is used to stamp out the coin blanks is misfed through the machine, it can cause the machine to punch down a second time on a blank. This results in a chunk of the coin being cut out.
- Double Die: Sometimes an image is accidentally stamped twice on a coin, making part of it (usually the text) appear slightly blurry. Double Die errors are arguably the most popular type of error coin.
- Off Center Coins: If a blank planchet gets out of place on its way through the striking process it is possible that it will only receive part of its image. The other part of the coin will be blank, causing the image to appear off center.
- Broad Strike: During the striking process coins are held in place using a collar which helps give the coin a nice, uniform rim. If a coin does not get placed in a collar prior to being struck, it may spread out a bit and make the rim look funny. This results in a coin that is wider than it should be and may or may not have a rim at all. See how the below penny is just as big as the nickel beside it?
- Overdate or over mint mark: Not everyone considers an overdate to be an error coin, but they are interesting. In the past, rather than creating new dies (stamps used to press the image on a coin), the mint just modified existing ones to include a new date or mint mark over the old one. If this modification was not done perfectly, it would result in the appearance of both dates or mint on the struck coin.
Depending on the type of error, these coins can be very valuable. The 1955 Double Die Lincoln cent is worth up to $1000. Many off center coins can be worth hundreds. Broad strikes are also fairly valuable ranging in price from $20 to $200. Value, like with all coins, is based on rarity and condition.
This list is only the tip of the iceberg when it comes to error coins. Errors can occur at anytime and for a variety of reasons . Although an error coin may be bad news to mint personnel, it is good news for collectors, proving once again that one man’s trash is another man’s treasure.