Common Errors in Coin Minting

Earlier this month, we covered 4 major error coins from around the world—some of which are worth thousands of dollars today. Now, here is a brief look at the wide variety of mint-made errors that coin collectors look for in their coin collections.

Off-Center Striking

One of the most common minting errors occurs when a planchet is fed through the press and lands in the collar improperly. This causes it to be misaligned with the upper and lower dies, and thus only a portion of the planchet is struck.

Double and Multiple Striking

Other times, after a coin is struck, it fails to be ejected out of the collar and down a chute. This results in the coin staying in place and being struck once again—or even a third time—resulting in a duplicated image on the coin.


The purpose of the collar in coin minting is to hold the planchet in place during striking and to form the outer edge of the coin. Broadstrikes happen when a collar isn’t in the proper place to retain a coin during striking, resulting in a distorted outer edge that spreads beyond the scope of the coin design.


Brockages are a little more complex than double striking. They occur when one coin is not ejected from the collar after striking, and then a second coin is fed into the collar for striking. Then when the second coin is struck, is receives an imprint from the bottom of the first coin’s top face. This imprint left by the first coin on the second coin is reversed.

Wrong Metal/Wrong Planchet Striking

Planchets are the blank metal coins on which dies are struck, and sometimes the wrong planchet is paired with the wrong die. One significant example is that of the 1942 one cent piece struck on a brass Ecuador 10 centavos planchet.


Simply put, mules are coins that have mismatched obverses and reverses. One recent example is the 2014 Britannia 1-ounce silver £2 bullion coin minted by the Royal Mint, which in several thousand cases featured an obverse or reverse from a bullion coin of a different collection—the new Lunar collection.

Transitional Errors

These errors occur when a certain denomination of a coin is struck on an old planchet intended for past collections of that coin denomination. One famous example is of the 1943 one cent coins that were struck on copper planchets instead of steel ones, as 1943 one cent coins were struck on steel.

Double Denomination Errors

This is one of the most desired and valuable errors to coin enthusiasts. Double denomination errors occur when one coin is struck on a previously struck coin instead of on a blank planchet. Some examples are of a nickel struck on a cent, or a cent struck on a dime.