Curious Die Events on 2026-P Emerging Liberty Dimes

Why Are 2026-P Dimes Developing Strange Waves, Spalls and Die Breaks?

The 2026 Emerging Liberty Dime already stands apart in modern U.S. coinage. For the first time since 1945, Liberty appears on the obverse of the dime. However, the new design may also offer collectors something much less obvious.

Philadelphia Mint examples have revealed several unusual die events [1]. Most appear in one remarkably small area: between the base of Lady Liberty’s neck and the date.

So far, these events fall into three basic groups. They include wave-like formations, surfaces that resemble incipient spalling, and larger interior die breaks. (Fig. 1)

Why These Die Events Appear in One Small Zone

The location matters.

Lady Liberty sits off center on the Emerging Liberty Dime. In addition, the base of her neck forms the highest peripheral relief along this part of the design.

Together, those features require an exponential die-face curvature [2] [3] between the neck and rim. As a result, this area rises higher and steepens more rapidly than much of the surrounding die surface.

Cross-sectional scans help illustrate the difference.

The area forms a deeper channel running from the base of Liberty’s neck, through the date, and toward the rim. On the die itself, however, that channel exists in reverse. Therefore, it forms an elevated zone above the adjoining field areas.

That geometry appears to concentrate pressure, stress, and shear during striking. Moreover, the effect increases where the exponential curvature begins to accelerate more rapidly.

In the following cross-sectional images (Fig. 2), a steeper angle represents a deeper channel.

Wave-Like Formations Below Liberty’s Neck

The first type of die event resembles a wave.

The example at left in Fig. 1 shows a raised formation that ends at an abrupt, step-like shoulder. A raised ledge follows the trough of that wave.

A 2000x scan makes the structure easier to see. [4]

However, the dime does not stand alone.

I have found a remarkably similar die event in front of the foresail on 2026-P Mayflower Compact Quarters. (Figs. 4, 5)

That comparison becomes especially important because the two coins share several unusual design characteristics.

First, both contain strongly changing curvature. On the dime, the exponential curvature runs from the base of Liberty’s neck toward the rim. On the quarter, the curvature extends around the coin’s circumference.

Second, both designs place unusually high relief near the periphery of the central design.

On the dime, scans show that the base of Liberty’s neck reaches the highest relief along the design periphery. It measures only 14µm below the highest relief I scanned anywhere on the obverse. That highest point occurs on the strand of hair below Liberty’s cap.

The Mayflower Compact Quarter presents an even more striking comparison. The forward edge of the foresail forms the highest relief measured on the quarter. It stands 26µm above the forward edge of the mainsail, which represents the next-highest relief point I scanned.

Finally, both coins place lower-relief devices near the rim directly opposite those high-relief features. The dime places the “2026” date there. The quarter places the letters “UN” in that zone.

Together, these factors create a valuable comparison between two very different coin designs.

One Die Event, Many Different Expressions

These die events do not always look identical.

Instead, 2026-P Emerging Liberty Dimes and Mayflower Compact Quarters display a surprisingly wide range of expressions.

The dime examples shown in Fig. 6 demonstrate several typical forms. However, they do not represent every variation I have encountered.

That variation makes the phenomenon more interesting. It also suggests an evolving event rather than a single isolated defect.

Nearly Identical Coins From the Same Rolls

Some examples provide another clue.

I found pairs in the same rolls that look virtually identical. That similarity raises the probability that the coins came from nearly successive strikes from the same die.

Fig. 7 shows pairs from three separate rolls.

Successive or near-successive strikes matter because they can help reconstruct how a die changes during use. Instead of examining one isolated coin, we may see different moments in the working life of the same die.

Could Die Flow Create These Waves?

I think die flow offers the most likely explanation for the wave-like events. [5] [6]  [7]

Collectors know conventional radial die-flow lines well. In fact, radial lines also appear between the date and rim on many of these dimes.

However, something different seems to happen directly below Liberty’s neck.

In this concentrated zone, die flow appears to develop into a wave. The wave then ends against a nearly vertical “wall.”

Why?

The answer may involve several forces acting together.

First, the die face follows an exponential curve below Liberty’s neck. Second, the base of the neck forms the highest peripheral relief of the central design. In fact, it comes within only a few micrometers of the highest relief anywhere on the obverse.

Those two features create competing metal-flow demands.

The high-relief neck requires substantial metal movement. Meanwhile, the lower-relief date requires much less.

Therefore, the area between them may become a transition zone. Metal moves from a region of high shear traction across the die face into a region of much lower shear traction.

That transition could support the formation of the apparent “wall.”

In this model, the metal-flow demands created by the high-relief feature serve as the primary driver.

Meanwhile, the exponential curvature adds another factor. Where that curve starts to steepen rapidly, it can concentrate pressure, stress, and shear beneath the neck.

That geometry may also encourage the wall-like termination.

A simple analogy helps.

Imagine a steady wind pushing loose sand. The wind builds a dune with one long, gentle slope. However, the opposite side can form a much steeper face.

The metal movement here may create an analogous flow pattern on a microscopic scale.

A Second Die Event: Incipient Spalling

Another group of 2026-P dimes shows something different.

Instead of a wave, the surface displays a large elliptical, flake-like area. Small cracks sometimes connect to it. (Fig. 8)

This appearance resembles incipient spalling.

In material-fatigue studies, early spalling can appear as a small and localized damaged area. Surface-breaking microcracks may develop first. Micro-pits and extremely shallow flaking or material pull-out may follow.

As the damage advances, the affected area can develop a roughened, V-shaped, or elliptical boundary. [8] [9] [10]

The limited zone of focus described earlier may contribute additional stress in this area of the dime die. That stress could generate cracks just beneath the surface and produce the incipient-spalling appearance.

The elliptical shape also raises another possibility.

This type of flake-like incipient spalling may occur specifically where die curvature becomes steep in two directions at once — both longitudinally and laterally.

If so, the die-to-planchet contact could create an elliptical contact patch.

That possibility deserves further study.

Subsurface Fatigue and Larger Interior Die Breaks

The third category takes the process farther.

Some events in this same zone grow large enough to qualify as Freestanding Interior Die Breaks. [11] (Fig. 9)

Repeated strikes may eventually move the die beyond the conditions that produce flow waves or incipient spalling.

Pressure and stress continue to accumulate. Eventually, those forces can create a subsurface shear zone.

Where a crack begins, and how that crack travels toward the surfac, helps determine the eventual thickness and shape of a spall.

Classical curved-surface contact mechanics provide a useful comparison.

For a circular Hertzian contact involving materials with typical metallic properties, maximum shear stress occurs below the surface at roughly 0.47 to 0.48 times the contact radius.

However, this dime does not present a simple spherical Hertzian contact. Its curvature changes substantially across the region.

Therefore, changes in load, curvature, and contact geometry could move the stress concentration and alter its depth. In turn, that could create spalls with uneven relief heights like the examples shown here.

The variation itself may prove important.

Die events with this combination of differing relief heights and surface morphology rarely appear, if they appear at all, on other U.S. coin dates and denominations.

The Emerging Liberty Dime may therefore present an unusual combination.

Its high-relief neck sits beside a field with rapidly steepening exponential curvature. Moreover, that curvature changes both longitudinally and laterally.

Together, those characteristics may create a contact patch with unusually large variations in pressure, shear, and curvature.

Why Do Philadelphia Dimes Show the Die Events?

One question immediately follows.

Where are the Denver examples?

Soon after Emerging Liberty Dimes entered circulation, sellers began offering examples of the die events discussed here. Almost without exception, the examples I encountered came from Philadelphia rather than Denver.

The scans may offer a clue.

The entire zone in the lower-left obverse quadrant forms an elevated curvature on the die. Relative to adjacent areas, that elevation changes both laterally and longitudinally by as much as 45µm.

The Philadelphia examples show a steeper elevation than the Denver coins examined in this comparison. (Fig. 10)

Combine that steeper geometry with the high-relief base of Liberty’s neck and the result may create a particularly concentrated zone of pressure, stress, and shear.

That concentration appears greater on the Philadelphia examples than on the Denver examples examined here.

As a result, it may change the metal-flow pattern. It may also contribute to subsurface microcracking of the die.

Philadelphia and Denver Die Crowns Do Differ

We know that die crown heights can differ between Philadelphia and Denver.

In fact, a United States Mint study reported enough difference in die crown heights and design relief heights between the two facilities to measurably affect coin fill. [12]

What we do not know is which mint normally uses the higher crown.

That distinction matters.

I previously suggested that Denver might use dies with higher crowns. [13] However, my continuing study of contact between curved surfaces now gives me reason to reconsider that interpretation.

Steeper curves can concentrate higher pressure, stress, and shear within the contact patch.

Therefore, I may have relied on a faulty syllogism.

The Mint encountered die breakage and shorter die life when it used flatter dies. Then, in 1836, the Mint moved toward spherical die faces and extended die life.

From that history, I reasoned that Philadelphia’s higher frequency of certain die events might indicate flatter dies than Denver uses.

However, these new scans complicate that conclusion.

Although the dies examined here show variable rather than simple spherical curvature, the measurements may point in the opposite direction. They suggest that Philadelphia could instead use dies with higher crowns.

At this stage, however, the evidence does not settle the question.

We need more research.

Perhaps a response to my Freedom of Information Act request will provide additional evidence.

A Fascinating New Chapter in U.S. Die Research

The 2026 Emerging Liberty Dime occupies a unique place in the history of American coin and die design.

Its unusual combination of peripheral relief, rapidly changing die curvature, concentrated metal-flow demands, and apparent die fatigue gives researchers an exceptional opportunity.

However, it also creates difficult questions.

My attempts to solve some of these mysteries have already led me down numerous dead ends. Yet those failures have made the subject more interesting, not less.

The wave-like formations may record unusual die flow. The elliptical patches may represent the beginning stages of spalling. Larger examples may document the progression toward subsurface fatigue and interior die breaks.

Meanwhile, Philadelphia and Denver examples may reveal something larger about modern die geometry and production practices at the two mints.

For collectors, that makes the 2026-P Emerging Liberty Dime more than a one-year commemorative circulating design.

It may also provide a rare window into how a modern coin die behaves under extreme and highly localized striking forces.

I suspect this journey has only begun.

CITATIONS

• [1] In the long-running discussion over what constitutes a variety versus an error, a third category may prove useful: the “Die Event.” Under this framework, a variety represents a variation created on the die, such as hub doubling or an RPM. An error represents a one-time striking event, such as wrong stock, a brockage, an off-center strike, or a double strike. A die event develops during the working life of the die and includes cracks, chips, fatigue, wear, abrasion, feeder-mechanism scrapes, misalignment, and related events.
• [2] Coin Die Design for the 21st Century: Did the 2026-P Dime Break a 100-Year Mint Rule? By Pete Apple, COINWEEK, June 25, 2026.
  https://coinweek.com/coin-die-design-for-the-21st-century-did-the-2026-p-dime-break-a-100-year-mint-rule/
• [3] Transitioning Curvatures of 2026-P Dime Coin Dies – How the 2026-P Emerging Liberty Dime Could Signal a New Era in U.S. Mint Die Engineering, by Pete Apple, COINWEEK, July 13, 2026.
  https://coinweek.com/transitioning-curvatures-of-2026-p-dime-coin-dies-how-the-2026-p-emerging-liberty-dime-could-signal-a-new-era-in-u-s-mint-die-engineering/
• [4] Coins were submitted to Shawn Tew of the Rabbit Hole Research Group, who arranged scanning at the Michigan State University Center for Advanced Microscopy using White-Light Interferometry / 3D Optical Profilometry.
  https://cam.msu.edu/
• [5] Paul Sebastian George Cross, Materials and Wear Modelling of a Cobalt-Chromium Alloy in Self-Mated Reciprocated Sliding, doctoral thesis, University of Southampton, Faculty of Engineering and Physical Sciences, National Centre for Advanced Tribology, April 2020.
  https://eprints.soton.ac.uk/447185/1/2020_06_15_Paul_Cross_Thesis_Final.pdf
• [6] Mostafa Gargourimotlagh, et al., “An Investigation into the Evolution of Surface Topography and Contact Characteristics of Rolling Elements Under Repeated Rolling Contact,” Tribology International, 208 (2025), 110644.
  https://pdf.sciencedirectassets.com/271465/1-s2.0-S0301679X25X00050/1-s2.0-S0301679X25001392/main.pdf
• [7] A.F. Bower, “Plastic Flow and Shakedown of the Rail Surface in Repeated Wheel-Rail Contact,” Wear, Volume 144, Issues 1–2, April 20, 1991, pp. 1–18.
  https://www.sciencedirect.com/science/article/abs/pii/004316489190003D
• [8] Researchers have documented similar elliptical flakes in studies of rolling-contact fatigue in bearings. Cyclic Hertzian contact stress can produce elliptically shaped spalls when microcracks begin at subsurface inclusions. See “Bearing Spalling – How It Starts, How It Spreads, and the Warning Signs Your Team Can Catch Early,” Reliability Solutions.
  https://reliabilitysolutions.net/resources/blog/bearing-spalling-how-it-starts-how-it-spreads-and-the-warning-signs-your-team-can-catch-early/
• [9] Elliptical Hertzian contact fields create subsurface stress distributions that can contribute to microcracking, pitting, and eventual flaking or spalling under repeated contact.
  https://engineeringnotes.org/solid-mechanics/hertzian-contact-stress/
• [10] Classical Hertzian theory does not strictly describe the dime examples because a single-point radius cannot describe an exponentially changing surface. Nevertheless, Hertzian contact theory provides a useful analogy for understanding concentrated contact stresses. See Chenxi Wei, et al., “A Contact Model for the Functionally Graded Coated Elastic Structures: Extension of the Hertz Theory to the Contact of Beam Structures,” State Key Laboratory of Nonlinear Mechanics, Institute of Mechanics, Chinese Academy of Sciences; School of Engineering Science, University of Chinese Academy of Sciences.
  https://www.sciencedirect.com/science/article/abs/pii/S0020768324003275
• [11] https://cuds-on-coins.com/interior-die-breaks-on-u-s-coins/
• [12] Alternative Metals Study, Contract Number TM-HQ-11-C-0049, Final Report, August 31, 2012, submitted to the United States Mint, p. 301.
• [13] Philadelphia Mint Errors: Why They Outnumber Denver Varieties.
  https://coinweek.com/philadelphia-mint-errors-why-they-outnumber-denver-varieties/