Part VI. Striking Errors:

Struck-Through Errors:

Surface Film Effects

Definition:  A thin film of oil on a planchet, a coin, or a die can produce a number of eye-catching effects. 

PART VI. Striking Errors:

Saddle Strike:

Head-to-Base Orientation

Definition: A saddle strike occurs when a planchet or coin receives two simultaneous off-center strikes by two adjacent die pairs.

While most saddle strikes show a head-to-head orientation of the two obverse designs, other orientations have been observed.  A head-to-base orientation is common in the early to mid-1970s, but does occur sporadically in other years.

This triple-strike is in the form of a flipover saddle strike on a previously struck, off-center cent.  The saddle strike shows a head-to-base orientation.

PART VI. Striking Errors:

Saddle Strike:

Head-to-Head Orientation

Definition: A saddle strike is defined as planchet or coin that received two simultaneous strikes from two adjacent die pairs.  Most saddle strikes show a head-to-head orientation of the two obverse designs.

The 1964(P) Lincoln cent pictured below failed to eject properly and ended up straddling two adjacent die pairs. It was then struck again. The tandem off-center strikes show the familiar head-to-head orientation.

Images are courtesy of Heritage Auctions.

PART VI. Striking Errors:

Saddle Strikes:

Wide Gap Between Adjacent Dies

Definition: The distance between adjacent striking chambers in dual and quad presses was increased in the mid- to late-1970s.  As a result, the size of the two off-center strikes is reduced relative to earlier saddle strikes.

The undated Lincoln cent saddle strike shown below has a wide gap between the two off-center strikes.

Images are courtesy of Heritage Auctions.

The post 1964 Roosevelt dime shown below became somewhat centered between two striking chambers resulting in a saddle strike.

PART VI. Striking Errors:

Saddle Strikes:

With Hump

Definition: A saddle strike occurs when a planchet or coin is struck simultaneously by two adjacent die pairs. Such a situation can only arise in a dual or quad press.  A quad press contains a total of four die pairs arranged in two couplets. The unstruck interval between the two tandem off-center strikes often buckles upward, forming a hump or a “saddle”.

PART VI. Striking Errors:

Saddle Strike:

No Hump:

Definition: A saddle strike occurs when a planchet or coin receives two simultaneous off-center strikes from two adjacent die pairs.  In most saddle strikes, the unstruck interval between the two off-center strikes bows upward to form a hump or a “saddle”.  When a hump doesn’t form,it’s still possible to diagnose the error.  Useful diagnostics include the following:

1. The lack of a “slide zone” in one or both off-center strikes.
2. A consistent orientation of the two strikes.  In most years, saddle strikes show a head-to-head orientation of the two obverse designs.
3. A consistent minimum distance between the two off-center strikes (e.g., about 11.5 mm in recent cents).
4. A slight tendency for one or both off-center strikes to squeeze beneath the unstruck part of the planchet.
5. The frequent presence of a low pressure ridge just medial to the internal margin of the off-center strike.

This is a flat saddle strike.  A slide zone is present on the larger strike because it is uniface.  The dies exert pressure on this part of the coin first because of the double thickness.  That allows a slide zone to sometimes form.  The smaller off-center strike shows no slide zone.

PART V. Planchet Errors:

Experimental Issues:

Statehood Quarters Struck on Experimental Alloys:

Definition: In the years 1999 and 2000, some statehood Washington quarters were struck on different alloys that were deemed acceptable for use in the minting of the Sacagawea dollar coins.

The U.S. Mint conducted metallurgical tests as part of its development of an alloy for what became the Sacagawea dollar. Presumably, quarter-size planchets and dies were more convenient to use than their mini-dollar equivalents. A small number of experimental planchet state quarters are known for each of the five 1999 states: Delaware, Georgia, Pennsylvania, Connecticut and New Jersey. These dies would have been available by early 1999 for production of proof sets. Some of the experimental planchet pieces were analyzed with energy-dispersive x-ray spectroscopy to determine their composition. The predominant metal was copper, followed by zinc, with traces of manganese and nickel present.

PART I. Die Subtypes:

Mid-year Design Modifications:

Date Position

The first Susan B. Anthony dollars were struck in 1979 at all three mint facilities (San Francisco, Denver and Philadelphia).

The obverse die design was modified with a “wider” rim late in 1979. This design change affects P-mintmark dollars only.

The date placement on the die did NOT change, only the design of the rim. This “wider rim” design modification only gives the appearance of the date having been re-located. In fact, all of the outer design features near the rim appear closer including the stars, LIBERTY, and IGWT, but the date is the most commonly mentioned aspect of this ‘wide rim’ modification.

PART VI. Striking Errors:

Multiple Strikes:

Second Strike Misalignment (Vertical)

Definition: After a centered first strike, the hammer dies tilts down at one pole and strikes the coin a second time at an angle.  The result is that one pole is extremely well-struck on both faces while the opposite pole shows little or no trace of the second strike.

The illustrated 1976 Israel Greeting medal was minted by the Israel Government Coins and Medals Corporation, a quasi-public entity that produces all of Israel’s coins and medals.  The first strike was quite weak, but was centered.  The second strike was delivered at an angle of approximately 45 degrees.

This medal shows both a vertical misalignment (tilted die error) and a 50% horizontal misalignment of the hammer die.  The hammer die started shifting position immediately after reaching the lowest point of its downstroke during the first strike.  As a result, newly-struck letters in the northwest quadrant were badly scraped.

Vertical misalignments of greater than 15 degrees are almost always accompanied by a horizontal misalignment.  This is because when a die tilts down at one pole, it also swings in, unless there is compensatory lateral movement of the die or die assembly in the opposite direction.