In my capacity as an error researcher I am frequently confronted
with unfamiliar and, at times, inexplicable errors. It is an
experience that most longtime collectors and researchers find familiar.
My colleague Robert “BJ” Neff was recently handed a doozy of a
mystery by error dealer Fred Weinberg. He sent Neff three 2011-D
Andrew Johnson Presidential dollars that show a peculiar effect on the
obverse face. All of the peripheral design elements display a shallow
dimpled field along their inner side. In other words, the dimples form
a centrally directed, converging radial pattern. The effect is easily
seen in the accompanying photos, all of which were taken by Neff.
The first problem to address was whether these dimples represented
a die error, a planchet error or a striking error. It was immediately
apparent that the anomaly was present on the die face. The dimples are
identical on all three dollars, and a careful study of die markers
undertaken by Neff showed that they were all struck by the same die
pair. The presence of dimples on the coin means that the field portion
of the die face must have been elevated right next to each peripheral
But what could produce such elevations? My thoughts initially
gravitated toward some form of die deterioration doubling. Incuse
forms of die deterioration doubling are known among copper-plated zinc
cents and on some state quarters. But I’ve never seen a case in which
the incuse doubling is located along the inner margin of the normal,
raised design elements. Most of the time the doubling extends from the
lateral margin of the affected design elements.
Finally, incuse die deterioration doubling is associated with
other signs of die deterioration, such as a swollen field or
concentric ripples in the field. None of the Andrew Johnson dollars
show signs of die deterioration; they seem to conform to an early die
state. Still, I can’t entirely dismiss a novel form of premature,
incuse die deterioration doubling.
Could the defects have been present on master die or a working
hub? Probably not, since we’d then expect the dimples to be more
widespread among Andrew Johnson dollars. Right now it looks like the
dimples are restricted to a single working die.
I had to abandon the idea that the dimples were caused by an
abnormally soft working hub or an abnormally hard working die. Either
could result in slight compression of raised elements on the face of
the working hub and possibly displace enough metal alongside each
element to a form pressure ridge. However, were that pressure ridge to
be driven into the face of the working die, it would leave a recess.
And that, in turn, would leave a bump instead of a dimple on the coin.
Neff has speculated that the dimples arose during the final phases
of hubbing as a result of uneven cooling and contraction of the
working die face. He correctly notes that the working die heats up
during hubbing as the harder working hub forces its way down through
the cone-shaped face of the unfinished working die.
After the “squeeze” is completed, the working die begins to cool
and, according to Neff, contracts ever so slightly. If the cooling and
contraction is uneven and particularly severe, one side of each
peripheral recess on the working die face might find its way blocked
by the corresponding raised element on the face of the working hub.
This could cause a slight pressure ridge to form before the hub is
lifted off the die face. The pressure ridge would be responsible for
the dimple on the coin’s surface.
While this scenario is possible, I would have expected the
phenomenon to have appeared before now and to be much more common.
Until we have a better understanding of the nature and origin of
these dimples, it’s best to assign them a nonspecific designation. I
would suggest something along the lines of “dimpled design extensions”
or “design extension dimples.” While I’m not a great fan of
placeholder terms, it’s the best we can do. We certainly wouldn’t be
alone in this. After all, astrophysicists have applied the terms “dark
matter” and “dark energy” to phenomena that they don’t understand.
I invite the readers of this column to submit other examples of
dimples. Perhaps other dies will show the effect. A larger, more
diverse sample might illuminate the situation.
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