Mint error coins continue to be exceedingly popular, and finds among the current year's population are virtually non-existent. This is due to the fact that the Mint has become far more efficient in their filtering techniques and employee monitoring. For example, coins had been counted at banks, where counting machine jams often resulted from error coins that had slipped through the Mint's inspection process. Now, however, coin is run through counting machines within the Mint to catch virtually all mistruck items. This can only mean a smaller supply for growing demand.

One important note...double-headed or -tailed coins are virtually all manufactured away from the mint and are not errors. They are produced from two coins ground and soldered together and are used to win coin tosses. They are available in magic shops for a few dollars, but have no collector value.

What follows are a few examples of highly unusual errors that government eyes and machinery have missed.

Triple Struck Coins

The eye appeal of the multiple strike error coin has made it one of the most sought after types. The more obvious the encroachment of the second and third strikes on the first strike, the greater the interest. More often than not, though, multiple strikes appear as almost shadows of previous strikes, being very close together due to the high speed machinery. What makes this type even more desirable is the appearance of more than one date, as well as the presence of the reverse image on the strikings (in lieu of uniface strikes, which are more common). The example at left is a recent Jefferson nickel that clearly has two additional strikes, one 75% off-center, and the other 90% off-center. The strikings are also referred to as DSBS, or Die Struck Both Sides. Distortion of the initial strike is evident from the additional strikings, partcularly on Monticello.

Capped Die Coins

A capped die is simply a coin that for some reason sticks to the upper die during striking, and through multiple strikings thins out and molds around the top or obverse die, forming a cap similar to a bottle cap or thimble. The greater the number of strikes, the higher the cap metal will be pushed around the upper die shaft. The cap error coin is an extremely spectacular error type which is quite scarce and virtually unavailable in larger denominations due to their smaller mintages. The present example is the plate coin on page 214 in The Error Coin Encyclopedia. It is a 1970 Denver minted cent that is particularly deep from numerous strikings, and having the reverse design virtually obliterated. Although deep die caps often have damage due to splitting off from the die, this specimen has nearly perfect facing and rims.

Off-Center and Cupped Coins

Probably the best known error coin type is the off-center. No two off center strikes are ever identical. The off center error occurs when the blank falls in a random manner so that it is partly off the lower die just prior to striking. Generally, the larger the coin, the more chance there is of the coin cupping, or bending when the die strikes. This creates a more dramatic appearance. The example is a 1964 Kennedy half dollar which was struck 70% off center and cupped. The strike is exceptional, and indicative of fresh dies. This particular item is rumored to have been in the personal collection of a mint official who was employed with the mint at the time.

3-Piece Bonded Set

Bonded coins occur when there is a major disruption of the planchet feeder system for the coinage presses. If the struck coin is not ejected properly and another planchet is fed into or near the same collar, part of that struck coin will land on top of the previously unejected strike. The two coins may be crimped and subsequently bonded together. If this process repeats, more will join in the bonding. Bonded coins rarely escape the mints, except through the shipping of bulk, uncounted but weighed coinage, or with the assistance of an unscrupulous mint employee. Recently, the Secret Service has determined that those bonded sets of more than three coins are subject to confiscation, due to the fact than most are from clandestine release. The specimen at left is a three-coin bonded set of 1990 Philadelphia minted cents. These items are exceedingly fascinating to view.

Double Denomination Coins

Another very dramatic mint error is a coin struck on a previously struck coin. An example of this type would be a cent struck on a previously struck dime. Here, we will see elements of each design on the struck coin. The wrong planchet error occurs from the use of older "tote bins" which are used to carry the blanks and struck coins from place to place. These are large steel tubs with sloped bottoms which allow the emptying of the bin completely when a slide trap door is opened. Occasionally, a blank or struck coin will remain stuck in the crevices of the bin and escape unnoticed. Later, when that particular bin is used to carry other struck coins, the trapped piece will be dislodged and mixed with the rest of the contents. Thus, double denominations happen. The coin displayed here is a 1996 dime which was later struck with cent dies. These double denominations tend to be the most common and least expensive of this error type, though they still command $400 to $700, depending on the date and grade.

Mules

Like the mix of a horse and donkey, a mule in coin errors is an unlikely combination of two incompatible entities: a different denomination from mismatched dies on each side. Although they are not uncommon in European and Asian coinages, the appearance of these in the U.S. is very rare, mainly because the different denominations are of differing diameters, so dies are generally incompatible. Recently, however, several mules have come to light. One which has received quite a bit of press is the Sacagawea dollar planchet and reverse/ Washington quarter obverse. 10 to date have made their appearance in the East and Mideast United States beginning in mid-2000. (Frank Wallis, the finder of the discovery, or first piece, had contacted Studium for information on its origin and authenticity. Pardon my momentary name-dropping.) Another mule of which only two have been discovered is a Lincoln cent planchet and obverse/Roosevelt dime reverse. One is dated 1995, the other 1999. Due to their extreme rarity, documented prices realized for this type of error have ranged from $25,000 to over $80,000.