The three types of errors found in US coinage are planchet errors, die errors, and striking errors or a combination of any of the three. The more popular mint error coins are listed below. Below that we have put together a photo gallery of Error Coin Examples
Coins can be struck off center and are measured by the percent off center. Broadstruck errors are struck out of the collar and are larger that a normal coin. Broadstruck errors range from small to huge.
Coins can be struck more than once resulting in double struck and multi struck error coins. Double and multi struck error coins can be struck on center, overlapping, off center and flip over. A saddle struck error coin is a double struck coin that happens when two sets of dies strike the coin at the same time resulting in a bend in the error coin.
A brockage error happens when an already struck coin gets struck together with a blank planchet or another coin. This leaves an impression of the details on the newly struck error coin. An indent error happens the same way but with a blank planchet leaving an impression with no details.
Clip errors happen when the blanks are punched out of the coin stock and then struck by US Mint dies. Clips can be curved, straight, crescent, elliptical, ragged, or bow tie. Coins can have multiple clips depending on how the blank was punched out. An incomplete clip error did not punch all the way through leaving the punch marks in the coin.
Double denomination error coins are coins that are struck on a previously struck coin of a different denomination. Popular examples are cents that are struck on a struck dime or a cent struck on a struck nickel. Other combinations are possible but much rarer. Off metal error coins are coins struck on the wrong metal such as a cent on a dime planchet or a nickel on a cent planchet. The photo gallery below shows a quarter struck on a cent planchet. Finger feeder error coins are struck on the aluminum "finger feeder" the pushes the blank planchets into the press.
Missing clad layer error coins are missing the clad layer on one side exposing the copper core and then struck by the mint dies. Split planchet error coins are split in half. The split can happen before or after the strike resulting in two completely different looks. A lamination error is a coin that is delaminating and parts of the coin have peeled off. An improperly annealed planchet error happens when the planchet is annealed too long and copper atoms move to the surface resulting in discoloration.
A struck thru error coin happens when something gets in-between the die and the planchet. The most common struck thru error is grease. Other popular struck thru errors are struck thru cloth, plastic, reeding, string, clad layers and coin fragments. It becomes a struck in retain error coin when the material is embedded in the coin and retained.
A die crack error coin happens when the die itself cracks and leaves an impression of the crack when the coin is struck. A die break or CUD happens when part the die breaks off and when struck that area fills in with metal because of the striking pressure.
Mated pair error coins happens when two coins are struck together and fit together. Bonded error coins happen when two or more coins are struck and fused together as one piece, Chain struck error coins are struck together while the edges are touching resulting in a straight edge on both coins where they meet.
A die cap error coin happens when a planchet get stuck on a die through multiple strikes and can have the shape of a thimble. Struck thru die caps error coins have an impression of the die cap on one side of the coin. A die adjustment error is an extremely weak strike, presumable when the mint adjusted the striking pressure. An edge strike error happens when a coin enters the coining chamber on its edge and the edge is then struck.
Off Center Error