When a blank plachet is not struck, and yet gets into the coin production, it is called "a blank plachet" error.

Adjustment marks are marks made in an attempt to adjust the weight of a coin. In the case of U.S. Coins, they usually appear on coins dated before 1840. Manufactures of that time was unable to make planchet of uniform size and weight. Since it was the weight of the base metal that determined the value of a coin, the weight was some times "adjusted" with a file, or some other device.

Bonded coins are created when the feeder system, which supplies blank planchets to the coin press jams. Then, a struck coin is not properly ejected and another planchet is fed into the collar and is struck. The coin will land on top of the unejected strike. This crushes the coins and they are bond together. This may happen several times.

Coin struck without a collar, thus when the coin is struck the metal is allowed to expand and increase in diameter. May be centered or uncentered, but must not have any missing lettering or design detail.

A mint error where a sharp incused image has been left on the next coin fed into the chamber.

A die that has warped in some way, producing coins that are slightly bent.

A die that has a small indentation formed in it, producing coins with a bulged area.

An error where a coin gets jammed in the press for successive strikes, eventually forming a "cap".

When a capped die strikes a previously struck coin, the obverse design from that struck coin will be impressed into the cap. The result will be a design where the cap face will be an incuse brockage.

A die adjustment strike is a type of mint error coin where the devices on the coin are struck improperly because the strike was made while a die setter was adjusting the coin press machine.

An error caused when a die has been struck a platchet more than once resulting in multiple design elements.

Double Denomination error is when a smaller coin is struck again by the dies of a larger coin.

This error occurs when a planchet receives impressions from dies of two different types (designs) of the same denomination.

A fold-over error occurs when the blank is standing vertically between the dies. During the strike, the force is so great that it bends and folds the blank.

When a blank planchet partially overlaps another planchet in the striking chamber and gets struck, the overlapping area on the struck coin will exhibit a blank indented area from the other planchet being struck into it.

If the alloy for the planchet was incorrectly mixed the result would be a flaked or peeled planchet. Lamination can also take place when contaminants are stuck to the plachet.

Coins created by a mismatched combination of dies. Dies of different denominations not meant to be paired such as a quarter on one side and a dollar on the other side.

A coin struck on a blank that was not properly centered over the anvil is called an "Off Center Strike".

A coin that has had a hole filled with a base metal to replace a more valuable metal is called a "Plugging Error".

A rough or granular surface sometimes even having small holes, is a "Porous Error".

Note the "shadow of a ring" in the center of the coin. This is called a spectacular error, but it does not fit into a special group.

This is a "struck fragment" error.

This is called a "Transitiional Error". The out of adjustment dies formed a "cup" on the obverse and a "cap" on the reverse.

This coin was stamped on the wrong planchet. It can be the wrong size, the wrong metal, or both.