Types of Mint Error Coins

Kennedy Half-Dollar Struck Off-Center
Kennedy Half-Dollar Struck Off-Center. Image Courtesy of: Heritage Auction Galleries, www.ha.com

An error coin is a coin that was not properly made during its manufacture. Error coins have problems such as being struck off-center, having the wrong planchet type, having the planchets improperly prepared so they are too thick, thin, not properly clad, or any number of other problems that occur during coin manufacturing.

Mint errors should not be confused with die varieties, which are coins that bear differences on their surfaces as a result of variations in the dies used to strike them, such as the way dates and mint marks were punched, or features that were doubled during die creation, etc.

The major determining factor between error coins and die varieties is that die varieties are reproduced hundreds or thousands of times because the error was on the coin die used to produce the coins.

Classification of Error Coins

There are three different classifications of error coins. Some error coins may have a combination of these problems.

  1. Die: Any die used to produce a coin that was not made in adherence with mint standards.
  2. Planchet: Any problem with the planchet that the coin was made on
  3. Strike: Any problem with the physical production of the coin in the coining press.

Types of Mint Errors

  • Die Cap - Occurs when a planchet is fed into the coining press, the previous planchet did not eject and the first planchet sticks to one of the coin dies. After repeated strikes, the first planchet starts taking the form of a bottle cap.
  • Wrong Planchet - The incorrect planchet is fed into the coining press and does not match the dies that are loaded in the press.
  • Off-Centers - The planchet is not centered between the two coin dies in the coining press.
  • Broadstrikes - The coining collar that holds the coin between the two dyes is not fully engaged in the coin is struck anyway.
  • Partial Collars - The coining collar is partially engaged in results in a malformed coin edge.
  • Brockages - One coin is struck on top of another coin in the coining chamber.
  • Double & Triple Struck - The coin is struck multiple times.
  • Die Adjustment - The coin is struck with not enough pressure due to the coin press operator adjusting the machine.
  • Bonded Coins - Two coins are struck together.
  • Double Denominations - A coin is first struck with one denomination and then fed through a coining press that has coin dies for a different denomination.
  • Coins Struck on Feeder Finger Tips - The coin press uses "feeder fingers" to feed the planchets into the coining press. Occasionally, the feeder finger gets struck with the coin design instead of the planchet.
  • Struck Fragments - Metal fragments from various sources can end up in the coining press and get struck with the coin design.
  • Proof Errors - Any proof coin that was not properly prepared according to proof coin standards.
  • Transitional Errors - When the mint changes from one metallic composition to another and a previous planchet with the old composition ends up getting struck as a new dated coins.
  • Fold-Over Strikes - A planchet is fed into the coining press in the vertical position and get struck on its edge instead of on its surface.
  • Missing Edge Lettering - Coins that are supposed to have lettering on the edge is missing. This is most prevalent on Presidential Dollars.

    Also Known As

    mint error

    See Also

    Die Varieties

    Example Usage

    The first error coin I ever got was a Lincoln penny that had been struck off center by about 85%. All you could see what the top of the president's head!

    Edited by: James Bucki