US Coins

High-standing Mint mark on cents: What can cause them?

The D Mint mark on 1987-D Lincoln cents is about as large as they come on Lincoln cents. Its raised perimeter also happens to be thin relative to the expansive interior.

As with any hand-punched Mint mark, the relief varies from one coin to the next. Relief depends on how deeply the letter was driven into the die, whether the die face was later abraded by Mint personnel, and how forceful the strike was. Intentional die abrasion lowers the field portion of the die, making any recess contained therein shallower. In the case of a weak strike, coin metal may not rise to completely fill the Mint mark recess. 

Beginning in 1990, the Lincoln cent Mint mark was incorporated into the design of the master hub, eliminating variability associated with letter depth in a fresh die. Also eliminated was variability in position.

Even in the midst of such variability, I’m still puzzled by two 1987-D Lincoln cents with Mint marks that truly stand out, both figuratively and literally. I discovered one example in pocket change and the second was discovered by Steve Burchfield. Since the two Mint marks occupy slightly different positions below the date, it’s clear they were struck by two different dies.

These Mint marks show relief that is dramatically greater than in normal cents. The accompanying photos show how the Mint mark protrudes in the form of a stubby plateau with sheer vertical walls. The interior of the Mint mark is nearly as elevated as the perimeter so that there is only a slight step-up to the perimeter. In normal cents the interior of the Mint mark lies at the same level as the surrounding field.

So what do these two outliers represent? Did the die setter in each case use too much force in tapping the letter punch into the die face? Was the letter punch defective? If it was defective, could it be that the perimeter of the letter was too low, necessitating increased effort to compensate for what otherwise would have been a weak Mint mark impression? Or could we be dealing with a hitherto unrecognized Mint mark style?

The elevated Mint marks are fractionally larger than the normal Mint marks among a sample of four 1987-D Lincoln cents I retrieved from a change jar. The maximum height (north to south) of the high-relief Mint marks is 1 millimeter as measured with an ocular micrometer. The maximum height of the four normal Mint marks ranges from 0.7 millimeter to 0.9 millimeter. For the high-relief Mint marks, the maximum width (east to west) is 0.7 millimeter if we exclude the serifs. The four normal Mint marks range from 0.6 to 0.7 millimeter in maximum width.

In my opinion, these modest differences in width and height do not constitute convincing evidence of a different Mint mark style. Width and height will vary for some of the same reasons that relief varies. 

A shallow punch mark will result in a smaller-looking letter because the letter perimeter tapers slightly in vertical cross-section. It’s the same reason why the weaker of the two Mint marks in a repunched Mint mark die variety often appears undersized. 

Intentional die abrasion will also shrink a Mint mark, and for similar reasons. As the field is lowered the Mint mark grows smaller because the recessed letter perimeter tapers as you go deeper into the die face.

Following this line of reasoning, a letter that is deeply impressed into the die face would be expected to yield a Mint mark on the coin that is fractionally larger than a series of normal Mint marks.

The high-relief D Mint marks appear to have the same shape as the normal series of Mint marks. The step-up from the interior of the high-relief Mint mark to the raised perimeter also seems fall within the same vertical range as the normal Mint marks.

Still, I’m not entirely comfortable with dismissing these high-standing Mint marks as simply an accident. The elevation of the two anomalous Mint marks is identical and there’s no continuity between their relief and that of any other Mint marks of comparable size within the Lincoln cent series. The presence of such a gap suggests that perhaps a different, flawed technique was used to drive the punch into the die face. If larger samples do eventually yield a continuum that fills the perceived gap between the high-relief and normal Mint marks, then we can put such speculations to rest.

I shouldn’t leave this discussion without mentioning low-relief Mint marks. Using the D Mint mark for convenience, we can identify three subpopulations: (1) low-relief Mint marks that have a narrow raised perimeter and an expanded interior, (2) low-relief Mint marks that have a raised perimeter and interior of normal dimensions, and (3) low-relief Mint marks with an expanded raised perimeter and constricted interior. 

Mint marks belonging to population 1 can reflect a weak tap by the die setter or the effects of intentional die abrasion. Population 2 can arise from a weak strike or from “grease” filling the corresponding recess of the die face. Population 3 is due to die wear. 

Note: An editing error incorrectly referenced a Canadian coin instead of a Kennedy half dollar in the last paragraph of the Sept. 22 column. See the corrected version here.


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