Just as nearly every family has it's "black sheep" (a member who is perceived as disgraceful or undesirable), so, too does virtually every coin series has it's failures. These are known as errors or mis struck coins, and have a following all their own. (Although freshly minted coins are carefully screened at the Mint, some errors manage to escape the process and land in mint-sewn bags, later to be sent to banks.) Both their scarcity and novelty attract new error coin collectors every year.

There are many different errors in processing and striking, but only the major types will be covered here. For the benefit of clarity, you can click on the examples to view enlargements, or place your mouse pointer over the underlined blue headings for a simplified animation on how this error was made.

Under normal circumstances, the striking process involves the introduction of coin "blanks" into the coin press, where they are struck, then ejected after hopefully make a good impression. (Insecure, the whole lot.) This is almost always the case, but, alas, the products of man are not always perfect....

Blank Planchet

Our first example is a blank planchet, or coin blank. (Blank planchet is easier understood than a blank blank. Besides, you might think I'm cursing.) There are two types: one which has been freshly cut in the blanking press (Type One), and one which has slightly raised rims after going through a softening process (Type Two). They simply slipped by the striking presses (probably couldn't stand the pressure, anyway). These are the most common type of error, with blank pennies trading among dealers for around 10¢ apiece.

Clipped Planchet

The clipped planchet error occurs during the stamping process, where thin sheets of metal are fed into a stamping machine that punches out rows of coin blanks. If the sheet shifts (don't say that too fast) during the process, blanks may have sections missing where previous blanks have been removed (see illustration), creating a curved clip. A straight clip, on the other hand, comes from an incomplete stamping along the edge. This is another relatively common error.

One of the more dramatic errors, the off center strike happens, as the animation illustrates, when a coin blank is mis-fed into the coin press and only part of the planchet is struck. Each error is different, and is categorized by two different measurements: The amount of the coin design that is visible (i.e., 25% off center), and where the off center design is located in reference to a clock. (The coin pictured would be off center at 2:00. I tend to wait until happy hour.) Some collectors make clocks with an appropriate off center coin at each hour on the dial face.

The double or multiple striking error can be the result from several situations. As the illustration shows, a double strike can occur from one die. However, the Mint utilizes two to four dies in close proximity to increase production. A multiple strike could also happen when a coin is struck, then bounces from table vibration into the path of another die. At press speed of two strikes per second, this is a possibility, as are other scenarios. This error is the most popular among collectors and the biggest attention getter.

Not to be confused with marital abuse, this error type occurs when dirt or debris lodge between the plate collar and the lower die, inhibiting its movement. If the die is stuck in the up position as shown in the animation, the planchet will spread into a bowl-like object when struck. If the entire design is visible on the error, it is considered a broadstrike. If, however, any part of the design is missing due to the coin not being centered under the die, then it's considered to be an off center error. This mis strike does not share the same level of popularity as other errors, but is still an important error type.


Prices of error coins vary considerably, and are based on denomination, date (if the date is visible), how significant the error, error type, how scarce the error is, and the dealer's demeanor. Usually the lower denominations (cents, nickels) are the least expensive. The most common type, blank cent planchets, can be had for as little as a few dollars, whereas the illustrated double struck nickel would be around US $35~$45.

Be aware that values of error coins have been stable and steady over the decades. This is not an investment hobby, but an enjoyable and educational experience, and a good illustration of our imperfect world.

Reference: The Error Coin Encyclopedia, Second Edition, Arnold Margolis, 1994


Copyright 2001 Dennel · All Rights Relinquished