In the Details

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I am always on the lookout for anomalies. More often than you might think, one tiny, seemingly insignificant difference between two coins reveals details of their manufacture that would otherwise have been lost to history. One of these irregularities fell in my lap recently in the form of a Lettered Edge $50 slug.

Weighing in at around 2½ ounces, $50 gold slugs were issued by the United States Assay Office at San Francisco starting in early 1851. The earliest of these massive gold coins are known as Lettered Edge slugs because the legend AUGUSTUS HUMBERT UNITED STATES ASSAYER OF GOLD CALIFORNIA 1851 was hand-punched into the rim of each piece. Originally intended to be struck in varying thicknesses and values, the preparation of each slug took 12 or 13 steps. The resulting coins are among the most fascinating numismatic objects I have ever encountered, and every example that crosses my path commands my full attention.

A Lettered Edge Slug Oddity

Not too long ago, I handled an example that was unlike any I had seen before: on its obverse, the transition from its face to rim was a sharp 90-degree angle, while its reverse edge was gently rounded. This was the exact opposite of what I’ve come to expect on a typical Lettered Edge slug. Once I’d carefully examined the coin to make sure that it hadn’t been repaired in some way, I began searching my image archives for other Lettered Edge $50s like it. After several days of digging, I was unable to find another example with similar rims. 

A careful examination and analysis of the anomalous slug alongside a group of regular Lettered Edge slugs suggested that the difference between them was caused by the shape of their planchets. Unlike the planchets used to strike most U.S. coins—which are identically shaped on both sides—the method used to create the octagonal blanks that the slugs were struck on seems to have resulted in a piece of metal that had a sharp, 90-degree edge on one side, and a softer, rounded edge on the other. Based on surviving Lettered Edge slugs I have examined, the side with a sharp edge was usually placed against the reverse die, resulting in slugs with a rounded rim on the obverse and a sharp rim on the reverse. In the case of the anomalous slug, the planchet apparently went into the press upside down.

Investigating the Anomaly

If this theory was correct, I wondered whether evidence of this unusual planchet shape would be visible on Reeded Edge slugs. These later pieces were struck with a single blow from two octagonal dies, unlike their Lettered Edge predecessors. Interestingly, a careful look at around a dozen 1851-dated Reeded Edge examples showed that the rounded edge of the planchet was usually positioned against the reverse die, the opposite orientation that I’d observed on Lettered Edge examples.

This change in planchet orientation would make sense because of the difference between Lettered Edge and Reeded Edge obverse dies. The Lettered Edge obverse was struck using a round die that was about the size of a $20 gold piece—this die was smaller than the resulting coin, and as such, the outer rim of a Lettered Edge slug remains unstruck. On a Reeded Edge slug, the obverse die is octagonal, with the legend and date engraved close to the edge of the coin. If the rounded edge side of the planchet were placed in the press facing the obverse die, the legend and date would fail to fully strike up.

Further investigation may turn up Reeded Edge slugs that were struck with the sharper edge facing the reverse die, and it will be interesting to see whether the legend is fully legible. It may also be the case that later examples were struck using planchets that were manufactured differently.

Conclusion

This is, of course, only the beginning of a proper study into the characteristics of the planchets used to strike these coins. Since I’ve begun looking into this subject, the information that it has revealed has helped me to identify a couple of repaired examples that may otherwise have slipped under the radar. It goes to show that there’s no such thing as useless information.