For those who collect split dies, the wider the chasm, the better.
A split die is a die crack that has propagated deep into the die
neck and die shaft, allowing the sides of the crack to spread far
apart. It appears on a coin as a conspicuous ridge that extends
between two widely separated points on the rim/edge junction.
The placement and course of a split varies considerably. A median or
bisecting split divides the die face into two equal halves. An
asymmetrical split leaves the die face divided into two unequal
portions. A split can be straight, curved, kinked, or irregular in its pathway.
There must naturally be a limit as to how wide a split can get
before one side breaks off. That limit is determined by the depth of
the split, the stiffness of the die steel, and how much bending stress
the steel can withstand before breaking. As a practical matter, the
limit can be determined only by measuring the dimensions of the very
In pursuit of this answer, I measured the widths of four impressive
split die errors from three countries. I used an ocular micrometer
that is accurate to the nearest tenth of a millimeter.
The first example is a 1973-D Roosevelt dime that I recently
obtained from error dealer Jon Sullivan. Almost straight and slightly
asymmetrical in position, the split runs from 11:30 to 6:00 (obverse
clock position). The spreading die face left the letters of LIBERTY
hugging the coin’s edge while, on the right side, the design rim
persists as a thin remnant.
The widest portion of the split is located over Franklin Roosevelt’s
cheek, but any measurement taken here would be deceptively large, as
it coincides with what appears to be an interior die break. The edges
of a split have a tendency to chip, especially in the center of the
die face. Extensive chipping may result in the formation of an
interior die break that straddles the split. In other cases, metal on
either side of the split’s midpoint sinks in, generating a die
subsidence error. The resulting swelling on the coin will also create
the appearance of excessive width.
I therefore chose to measure the two ends of the split, which appear
to be clean, original fractures. At 11:30 the split measures 0.7
millimeter, while at 6:00 it measures 0.8 millimeter. This is the
widest split I’ve seen in a dime, matched only by a 1965 dime struck
by a split obverse die.
An equally wide split is found on the obverse face of a 1980-P
Jefferson 5-cent coin. Where it meets the edge at 9:30 it measures 0.7
millimeter. Where it meets the edge at 3:30 it measures 0.8
millimeter. The die face spread out to such an extent that the letters
of LIBERTY are cut off at the coin’s edge.
The next coin — a 1995 25-paise piece from India — was struck by a
badly split, horizontally misaligned reverse (hammer) die. The split
occupies a highly asymmetrical position in the southern half of the
reverse face. It pursues a relatively straight path except for a short
downward bend on the right. An elongated interior die break prevents
accurate measurements along the split’s middle portion. But once
again, the ends of the split are free of such secondary breakage and
both measure 0.8 millimeter in width.
Our final example is a 1991 10-kopek coin of Russia. An
asymmetrically positioned split appears in the southern hemisphere of
the obverse face, which I suspect was struck by the hammer die. An
elongated interior die break straddles the left side of the split, but
does not extend to its left terminus. The left end of the split
measures 0.6 millimeter while the right end measures 0.8 millimeter.
Even though this sample of exaggerated split dies is small, the
close similarity in their measurements suggests that they’ve reached
the upper limit for spread. That upper limit doesn’t seem to be
related to the overall diameter of the die face and die neck.
Therefore, while the absolute measurements of the splits are similar,
they are proportionally widest in smallest denominations.
The widest splits seem always to be associated with the hammer die.
This makes a degree of sense, since the anvil die is confined by the
collar, and the latter would tend to limit spread.
If any reader comes across a split that measures a millimeter or
more in width, please let me know.
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