The Science of the Strike: A Metallurgical Breakdown of the 1938-S Texas Commemorative Half Dollar

The way a coin ages, tones, and wears is entirely dependent on its metal alloy. Here is a scientific breakdown of this piece.

When I first laid eyes on the images of this 1938-S Texas Independence Centennial Commemorative Half Dollar posted in the forum thread, my mind immediately went not to the grade — though that was the subject of spirited debate — but to the metal itself. What is happening beneath the surface of this coin? What can the alloy, the planchet preparation, the strike pressure, and the resulting metal flow lines tell us about why this particular specimen looks the way it does, and why it earned the grade it did? As a metallurgist who has spent decades examining U.S. commemorative coinage under magnification, I can tell you that the story of this coin is written in its crystalline structure just as much as it is in its design. Let’s break it down.

Alloy Composition: The Foundation of Everything

The 1938-S Texas Commemorative Half Dollar, like all U.S. silver commemorative half dollars of its era, was struck in a 90% silver, 10% copper alloy. This is the same composition used for all circulating U.S. silver coinage from 1837 through 1964, and it is a deceptively simple recipe that produces remarkably complex behavior over time.

From a metallurgical standpoint, the 90-10 silver-copper alloy is a solid solution. The copper atoms are dispersed within the silver crystal lattice at the atomic level, and this dispersion is what gives the alloy its hardness, its resistance to wear, and — critically — its luster characteristics. Pure silver is far too soft for coinage. The 10% copper addition increases tensile strength and resistance to deformation, but it also introduces subtle changes in how the metal flows during striking, how it reflects light, and how it develops toning over decades of environmental exposure.

For the 1938-S Texas Commem specifically, the alloy composition is significant because this was a low-mintage issue — only 5,000 pieces were struck at the San Francisco Mint. Low-mintage issues from this period were often struck with greater care, using freshly prepared planchets and carefully maintained dies. The alloy itself would have been consistent with other San Francisco Mint products of the year, but the quality control on commemorative issues was typically tighter than on mass-produced circulating coinage.

What does this mean for the collector examining this coin today? It means that the blazing luster described by the original poster is not merely an aesthetic observation — it is a direct reflection of the alloy’s crystalline integrity. When a 90% silver coin retains its original mint luster after 85+ years, it tells us that the metal has not undergone significant surface degradation, oxidation, or environmental attack. The copper component of the alloy is what typically causes toning and discoloration over time, as copper atoms migrate toward the surface and react with sulfur compounds in the atmosphere. The fact that this coin displays attractive, even toning rather than dark, mottled discoloration speaks to both the quality of the original planchet and the conditions under which it has been stored.

Planchet Preparation: The Unsung Hero of Coin Quality

Before a single die ever touches a blank piece of metal, the planchet has already been through a rigorous preparation process that profoundly affects the final appearance of the coin. Understanding planchet preparation is essential to understanding why some coins grade higher than others — even when they come from the same mint in the same year.

The planchet preparation process for 1930s U.S. Mint commemorative coinage involved several critical steps:

1. Casting: The 90-10 silver-copper alloy was melted in induction furnaces and cast into long, rectangular ingots. The consistency of the melt — temperature, duration, and atmospheric conditions — determined the uniformity of the alloy at the microscopic level.
2. Rolling: The ingots were passed through a series of rolling mills to reduce them to the precise thickness required for half dollar planchets. This cold-working process introduced internal stresses into the metal and began to align the crystalline grain structure in the direction of rolling.
3. Blanking: Round planchets were punched from the rolled strip. The orientation of the grain structure relative to the coin’s faces would later influence how metal flowed during striking.
4. Annealing: The blank planchets were heated to approximately 1,100–1,200°F and then slowly cooled. This process relieved the internal stresses introduced during rolling and blanking, softening the metal and making it more receptive to striking. Proper annealing is critical — under-annealed planchets are too hard and resist full die contact, while over-annealed planchets can develop surface oxidation and a dull, lifeless appearance.
5. Cleaning and Blanching: After annealing, the planchets were washed in acid solutions to remove surface oxidation and then dried. This step gave the planchets their final, bright silver appearance before striking.

For the 1938-S Texas Commem in question, the quality of planchet preparation is evident in the coin’s overall appearance. The forum participants noted “blazing luster” and described the coin as “very attractive.” In my experience, this level of surface quality indicates that the planchet was properly annealed and cleaned before striking. The metal was in an optimal state to receive the full detail of the dies, and the resulting coin displays the kind of vibrant, cartwheel luster that is the hallmark of a well-prepared planchet.

One thing I always tell collectors: you cannot fix a bad planchet with a strong strike. No amount of die pressure can compensate for a planchet that was improperly annealed, contaminated, or poorly cleaned. The foundation of a high-grade coin is always the planchet, and this 1938-S Texas Commem clearly benefited from excellent planchet preparation.

Strike Pressure: Where Engineering Meets Art

The strike is the moment of transformation — the instant when a flat, featureless disc of metal becomes a coin. From a metallurgical perspective, the strike is a complex event involving enormous pressures, rapid metal flow, and the interaction between two hardened steel surfaces and a softer metal planchet.

The U.S. Mint’s presses in the 1930s were capable of exerting pressures in the range of 100 to 150 tons per square inch for half dollar coinage. When the dies come together under this kind of force, the metal planchet is forced to flow into every recess of the die design. The speed and direction of this metal flow determine how completely the design is rendered, and the evidence of this flow is permanently recorded in the coin’s surface.

For the 1938-S Texas Commemorative, the strike quality is a key factor in the grading debate that unfolded in the forum. Participants guessed grades ranging from MS64 to MS67 — a spread that reflects the difficulty of assessing strike quality from photographs alone. Let me explain what I look for when evaluating strike on a Texas Commem:

• Alamo detail: The Alamo building on the reverse should show clear architectural detail, including the windows, the roofline, and the curved parapet. Weakness here indicates insufficient metal flow into the die recesses.
• Eagle’s wing feathers: The eagle on the reverse should display fully separated, sharply defined feather detail. This is one of the first areas to show weakness on a softly struck specimen.
• Star centrils: The six stars on the obverse and the single star on the reverse should be fully formed with sharp points. Rounded or incomplete stars are a sign of inadequate strike pressure or die wear.
• Letter sharpness: The inscriptions — IN GOD WE TRIBUTE, TEXAS INDEPENDENCE, and the date — should be crisp and fully raised from the field. The forum poster’s note about the “dash” (not a “T”) between “TEXAS” and “INDEPENDENCE” is a good example of the kind of fine detail that separates a sharp strike from a mediocre one.

Based on the images and the descriptions provided, this coin appears to have received a full, sharp strike with complete die detail. The fact that multiple experienced graders in the forum landed on MS65 and MS66 suggests that the strike was not a limiting factor in the grade. In my assessment, the strike pressure was sufficient to fully fill the dies and produce a coin with sharp, well-defined design elements across both obverse and reverse.

Metal Flow Lines: The Hidden Fingerprint of the Minting Process

Now we come to one of the most fascinating — and most misunderstood — aspects of coin metallurgy: metal flow lines. These are the microscopic (and sometimes visible) lines that form on a coin’s surface as metal flows outward from the center of the planchet during striking. They are the coin’s hidden fingerprint, and they tell us an enormous amount about how the coin was made.

When the dies strike the planchet, the metal does not simply compress — it flows. The metal at the center of the planchet is squeezed outward toward the rim, and this outward flow creates parallel lines in the metal’s crystalline structure. Under normal lighting conditions, these flow lines are invisible. But when a coin is tilted under a light source, the flow lines become visible as a series of concentric, radiating patterns — this is what collectors call “cartwheel luster.”

The presence of strong, unbroken cartwheel luster on the 1938-S Texas Commem is one of the most important indicators of its grade. Cartwheel luster is only present on coins that have not been cleaned, polished, or excessively handled. Once the surface flow lines are disrupted — by wiping, dipping, or even aggressive storage — the cartwheel effect is diminished or destroyed entirely. The fact that this coin displays blazing luster with a strong cartwheel effect tells me that the original mint surface is intact and undisturbed.

But there is another type of line that appears on coins — and this is where the forum discussion gets particularly interesting. One participant, @Morgan13, asked about visible lines on the coin, wondering whether they were on the holder or the coin itself. Another experienced collector, @jfriedm56, correctly identified these as mint-made die polishing lines — lines that were transferred from the die to the coin during striking.

Die Polishing Lines: Mint-Made, Not a Defect

Die polishing lines are among the most commonly misunderstood features in numismatics. They are not scratches, gouges, or post-mint damage. They are raised lines on the coin’s surface that result from polishing marks on the die itself. When the Mint prepared the dies for the 1938-S Texas Commemorative, the die sinkers polished the die surfaces to remove imperfections and create a smooth, reflective field. Any scratches or tooling marks left on the die during this polishing process were then transferred to every coin struck by that die.

Here is the critical metallurgical distinction: die polishing lines are raised features, not incised ones. They sit on top of the coin’s surface, pushed up by the pressure of the strike. This means they are part of the original minting process and do not represent damage to the coin. In fact, die polishing lines are so common on Texas Commemorative half dollars that their absence is more noteworthy than their presence.

For grading purposes, die polishing lines are generally not considered detracting features unless they are severe enough to disrupt the overall visual appeal of the coin. The lines visible on this 1938-S Texas Commem appear to be moderate in nature — noticeable under magnification and in certain lighting conditions, but not prominent enough to significantly impact the coin’s eye appeal. This is consistent with the MS65-MS66 grade range suggested by most forum participants.

The Grading Debate: What the Metal Tells Us

The forum thread produced a wide range of grade guesses for this coin, from MS64 to MS67. As a metallurgist, I find this spread illuminating because it highlights the subjective nature of grading and the importance of understanding what you are looking at when you evaluate a coin’s surface.

Let me break down the key surface characteristics that would influence the grade, from a metallurgical perspective:

• Luster: The coin displays strong, original mint luster with a vibrant cartwheel effect. This is the single most important factor in distinguishing MS65 from MS64. Coins at the MS64 level often show slightly muted or interrupted luster, while MS65 coins display the kind of blazing, unbroken luster described by the original poster.
• Contact marks: Several forum participants noted “hits” and “a couple large and noticeable” marks. From a metallurgical standpoint, contact marks are areas where the coin’s surface has been physically displaced — the metal has been pushed aside by impact with another coin or object. The number, size, and location of these marks are critical to the grade. Marks in the open fields are less distracting than marks on focal points like the Alamo, the eagle’s breast, or the portrait of Sam Houston.
• Die polish lines: As discussed above, these are mint-made features and are not considered detracting. However, if they are particularly heavy, they can create a slightly “busy” appearance that some graders may find less appealing.
• Toning: One participant noted what appeared to be “toning marks” near the “S – OF” area of the reverse. Toning is a chemical process — the reaction of copper atoms at the coin’s surface with sulfur, oxygen, or other environmental compounds. Attractive, even toning can enhance a coin’s eye appeal and grade, while dark, splotchy toning can detract from it. The toning on this coin appears to be light and attractive, which is a positive factor.
• Scuffs: One collector, Jim, noted a “black lengthy scuff looking mark to the left of right facing wing and spot on star” that he felt would prevent a grade of MS66. Scuffs are surface abrasions that disrupt the metal flow lines and diminish luster. They are among the most grade-limiting types of surface disturbance because they are visible even under casual inspection and cannot be attributed to the minting process.

Taking all of these factors into account, I would assess this coin as a solid MS65 to MS66, with the final determination depending on the severity of the scuff and contact marks noted by forum participants. The luster is clearly at the MS66 level, but the surface marks may pull it back to MS65. This is exactly the kind of coin where two experienced graders can reasonably disagree — and that is precisely what we saw in the forum thread.

Actionable Takeaways for Buyers and Sellers

Whether you are considering purchasing a 1938-S Texas Commemorative or you already own one and are thinking about selling, here are the key metallurgical factors to evaluate:

1. Always examine luster first. Tilt the coin under a light source and look for the cartwheel effect. Strong, unbroken cartwheel luster is the hallmark of a high-grade coin and is the single best indicator that the original mint surface is intact.
2. Distinguish between mint-made features and post-mint damage. Die polishing lines, flow lines, and light mint-caused marks are not grade limiters. Scuffs, scratches, and cleaning marks are. Knowing the difference can save you from overpaying or underselling.
3. Evaluate toning carefully. Attractive, original toning can add to a coin’s value and eye appeal. Artificial toning or harsh cleaning will destroy it. If the toning looks uneven, splotchy, or artificially enhanced, proceed with caution.
4. Consider the strike in context. The 1938-S Texas Commem is not known for weak strikes, so a softly struck example may indicate die wear or improper press setup. A fully struck coin with sharp detail throughout is more desirable and more likely to hold its value.
5. Get a professional opinion for borderline coins. Coins in the MS64-MS66 range can be difficult to grade from photographs alone. If you are buying or selling a coin at this level, consider having it examined in hand by a professional numismatist or submitting it to a third-party grading service like PCGS or NGC.

Historical Context: Why the 1938-S Texas Commem Matters

The 1938-S Texas Independence Centennial Commemorative Half Dollar occupies a special place in American numismatic history. It was issued to commemorate the 100th anniversary of Texas’s independence from Mexico in 1836, and it was part of the great commemorative coin boom of the 1930s — a period when the U.S. Mint issued an extraordinary number of commemorative designs, many of which are highly sought after by collectors today.

The Texas Commem series was produced from 1934 to 1938 at three mints — Philadelphia (no mint mark), Denver (D), and San Francisco (S). The 1938-S issue had a mintage of just 5,000 pieces, making it one of the scarcer issues in the series. Low mintage, combined with the historical significance of the Texas Centennial and the attractive design by Pompeo Coppini, has made this coin a perennial favorite among collectors of U.S. commemorative coinage.

From a metallurgical and investment standpoint, the 1938-S Texas Commem is an excellent example of a coin that benefits from both its numismatic premium and its intrinsic silver value. Even in lower grades, the silver content provides a floor for the coin’s value. In higher grades — MS65 and above — the numismatic premium becomes the dominant factor, and well-preserved examples command significant premiums over melt value.

As one forum participant correctly noted, “Texas Commems — always a good investment.” This is especially true for coins with the kind of strong luster, sharp strike, and attractive surfaces displayed by the coin in this thread. Coins that are “accurately graded” — as the original poster assured us this one is — are the coins that hold their value best over time, because buyers can trust the grade and pay accordingly.

Conclusion: The Metallurgist’s Verdict

The 1938-S Texas Commemorative Half Dollar examined in this forum thread is a beautiful example of early 20th-century American commemorative coinage. From a metallurgical perspective, it displays all the hallmarks of a well-made, well-preserved coin: strong original luster with vibrant cartwheel effect, a full sharp strike with complete die detail, attractive original toning, and only moderate contact marks and mint-made die polishing lines that do not significantly detract from its eye appeal.

The alloy composition — 90% silver, 10% copper — has served this coin well over its 85+ years of existence, providing the hardness needed to resist excessive wear while allowing the kind of brilliant, reflective luster that makes high-grade silver coins so visually stunning. The planchet preparation was clearly excellent, providing a clean, uniform surface for the dies to work with. The strike pressure was sufficient to fully render the design, and the resulting metal flow lines create the cartwheel luster that is the visual signature of an original, undisturbed mint surface.

The grade debate in the forum — ranging from MS64 to MS67 — reflects the genuine difficulty of assessing a coin’s grade from photographs, where lighting, focus, and camera angle can all influence perception. My metallurgical assessment places this coin firmly in the MS65 to MS66 range, with the luster supporting the higher end and the contact marks and scuff noted by some participants potentially limiting it to the lower end.

For collectors, this coin represents exactly the kind of quality that makes the Texas Commemorative series so enduringly popular: low mintage, historical significance, beautiful design, and — in this case — exceptional surface quality. Whether you are a seasoned numismatist or a newcomer to the hobby, understanding the metallurgy behind what you see when you look at a coin will make you a better collector, a smarter buyer, and a more confident evaluator of the coins in your collection. The metal tells the story. You just have to know how to read it.

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