Definition: A coin is struck a second time by dies of the same denomination but bearing a different year. This is an extreme example of a delayed second strike.
This 1951-D Lincoln cent was struck a second time by dies that were striking 1964-D Lincoln cents.
Images are courtesy of Heritage Auctions.
The 1963-D Lincoln cent shown below was struck a second time with 1964-D cent dies.
Images are courtesy of Heritage Auctions.
Definition: This error occurs when the coin is struck at least twice with one of those strikes showing a rotation of either the hammer or the anvil die.
On rare occasions a double-struck coin will show that one of the dies (almost always the hammer die) rotated between strikes. Such errors are most common on proofs from the late 1960’s and early 1970’s. This 1966 nickel shows a rare business strike with such an error. The hammer (obverse) die rotated about 15 degrees between the
first and second strike. This coin comes courtesy of Thomas Barosko.
Definition: This error occurs when a coin is struck at least twice and the subsequently strikes shows an offset in direction.
A horizontal, vertical, pivoted, or rotational misalignment can occur on the second strike after a normal first strike. It’s also possible for a misaligned die strike to precede a normal second strike, although this has only indirectly been documented through clash marks.
In this 1999 cent, the hammer (obverse) die was centered during the first strike. Between the first and second strike, it shifted to the right about 10%. Before the hammer die descended a second time, an unstruck planchet intruded into the striking chamber, leaving an indent on the left side. Details of the first strike can be seen in the floor of the indent. The second strike also shows a partial collar error
Definition: A coin struck through a late-stage die cap that has become dislodged and shifted out of position. It generally produces a set of incuse, normally-oriented design elements, i.e., ones that face the same way as their normal raised counterparts.
A late-stage die cap molds itself to the recesses of the die face. The floor of the cap is thinnest where it overlies the field portion of the die face. The cap floor is slightly thicker in the recesses of the die face because effective striking pressure is slightly lower there. When a die cap shifts out of position, those slightly thicker areas are driven into the next planchet, producing the normally-oriented, incuse design elements.
A die cap can rotate, shift laterally, or both. The 1990 cent shown here was struck through a die cap that shows a combination of movements.
This 1990 cent was struck once through a late-stage obverse die cap. The cap had rotated 180 degrees and shifted laterally to the north immediately before it struck the planchet represented by this coin. An extensive set of normally-oriented incuse design elements overlies the strong ghost of Lincoln that bled through the cap from the obverse die. A sunken arc at the southern pole of the obverse face marks the “zone of collapse” where the wall of the cap was telescoped and crushed into the planchet.
Definition: A sideneck strike involves a collision between the unstruck edge of an off-center coin and the neck of the adjacent hammer die. During an off-center strike, the struck tongue of metal expands in all directions. This expansion pushes the unstruck portion of the planchet sideways. If it’s positioned just right, the pole opposite the struck tongue of metal will collide with the adjacent hammer die.
A sideneck strike leaves a smooth, curved indentation at the pole opposite the off-center strike. This error is as close as you can come to a saddle strike without actually being a saddle strike. Sideneck strikes often show a pattern of buckling identical to that of a humped saddle strike.
Other terms used to refer to this error include “almost saddle strike” and “one-die saddle strike.”
The Lincoln cent shown below shows an off-center strike in association with a sideneck strike. The characteristic concave facet is easily seen.
Definition: In this form of doubling, a die drags itself through the newly-struck design, smearing the features. Strong cases of slide doubling are always restricted to the face struck by the hammer die. After reaching the lowest point of its downstroke, the hammer die shifts to one side without bouncing. As it drags itself across the newly-struck design, it piles coin metal into a series of ridges. Weak cases of slide doubling found on the reverse face have previously been assigned to “ejection doubling”, but there is no way to prove that this is actually what happened.
Forms of machine doubling combining elements of both push doubling and slide doubling do occur.
A very severe case of slide doubling is seen on this 2001-D cent. As is often the case, it is accompanied by a design ablation error. The hammer die first contacted the coin in a centered position. As it sank down into the planchet, the hammer die shifted to the northeast, erasing the newly-struck design in a crescentic area in the southwest. Having completed its downstroke in a misaligned position, the hammer die then shifted back toward the southwest, dragging itself through the newly-struck design. The design is grotesquely smeared as a result.
On the two examples (Kennedy half and Washington quarter) the green arrow indicates the direction the die traveled as contact was made (Die Ablation), with the white arrow showing the scraped planchet face. The red arrows show both the direction the die took as it returned and also shows the areas where the metal was moved and piled up. The light green arrows show details of the Slide Doubling on the Kennedy half.
Definition: A pattern of deformation that is premature, exaggerated, peculiar, and often localized. It is closely related to die subsidence (sunken die) errors. Instead of the die face sinking in, the metal on the die face moves around more-or-less within the plane defined by the original die face. Many soft die errors feature some sinking-in of the die face.
Soft die errors can be caused by improper die preparation (annealing, tempering, quenching). They can also be caused by use of the wrong steel, or improper forging of the die steel up to and including the point when it is extruded into a long rod. Improper forging can introduce contaminants into the die steel or create the wrong ratio of carbon to iron, as well as other alloy components.
The above photograph portrays the 1943-S “goiter neck” quarter. The left side of the obverse face shows a soft die error. A bulge is located beneath Washington’s throat (the “goiter”). Here the die face sank in slightly. The motto IN GOD WE TRUST appears to be written in italics. A low ridge runs through the LIB of LIBERTY and the design rim has vanished from about 6:00 to 11:00. Since only this die is affected, the problem was likely caused by faulty die preparation. All coins struck by this die pair show the same degree of deformation, suggesting that the deformation started shortly after installation and then stabilized.
This 2000-P New Hampshire quarter has a dramatic soft die error on the obverse face. A low, broad, irregular ridge runs through QUARTER DOLLAR and continues beyond it on both sides. The letters of UNITED are grossly distorted. The center of the design shows little evidence of die deterioration. Modest development of a similar ridge can be seen on the reverse face. A similar soft die error can be seen on some New York quarters. The pattern of deformation bears a passing resemblance to the “ridge rings” that frequently develop on copper-plated zinc cents.
The appearance of a coins surface can be altered by the addition of solder. Where it is to alter the appearance of a design element or to add an independent feature (die crack and such), it can be accomplished to a degree where it may fool the average collector.
Below is a 1918(P) Lincoln cent that has had solder added both to the obverse and reverse of the coin’s surface.
Definition: The term “struck-through” (or struck-through) is a non-specific label for a coin that is struck through just about anything – grease, debris, plastic, metal fragments, etc. Strike-throughs that involve large, thick, solid objects are rarer and more desirable than other types. Rarest of all are coins that are actually torn asunder when a foreign object is struck into them.
Key diagnostics for a coin torn apart by a foreign object are as follows:
This off-center 1982 cent was struck through a threaded bolt on the left side. The left side of the coin was pinched off and lost as a result of the impact.
Coin courtesy of Sean Reynolds.
Definition: Split planchet errors are normally restricted to planchets comprised of a solid metal alloy including aluminum, bronze, nickel, & silver.
A split after strike planchet will always weigh less than a normal planchet. A fine to coarse striation pattern will be clearly evident on the face which splits away.
1959 Lincoln memorial cent whose reverse face split off after after being struck. Notice the obverse face has a strong strike. The entire memorial reverse face is gone and instead only a muted, striated ghost of the memorial building and Lincoln’s profile can be seen. This split layer weights 1.4 g.
Another example of a split planchet after the strike is this 1945 Jefferson nickel. The reverse of the coin split away after the coin was struck leaving a 3.1 gram obverse.
