One of the rarest forms of brittle die fracture is the split die. A
split die is an overgrown rim-to-rim die crack that extends deep into
the die neck. The sides of the split spread apart, leaving a thick
raised line on the surface of the coin. A split can bisect a die (a
median or bisecting split) or can lie off to one side (an asymmetrical
split). It can be straight or curved.
Shown here is a 1980-P Jefferson 5-cent coin struck by an obverse
die with a very wide median split. The northern half of the die
splayed out so far that the word liberty is cut off along the edge of
As rare as they are, many current split dies may have to be
downgraded. This revelation was sparked by a 1974-D Jefferson 5-cent
coin recently acquired from Ronnie Braswell. The reverse face seems to
show a median split die. However, the two arms of the presumed split
fail to meet in the center. Instead, they pinch out as they enter a
weakly-struck bulge in the middle of Monticello. The bulge represents
a die subsidence error.
The portico of Monticello is weakly struck because the sunken
portion of the die was too distant from the planchet to generate much
striking pressure. Nevertheless, the design is complete, and it is
clear that no die crack crosses it or passes above or below it.
Instead of a split die, what we have is a pair of radial,
antipodal die cracks. This finding calls into question the status of
many median split dies, as these are frequently interrupted in the middle.
A typical gap is displayed in a 1974-D Roosevelt dime. The two
arms of the presumptive split disappear into a featureless bulge —
also a die subsidence error. The absence of design details is partly
due to reduced effective striking pressure in this area. But it also
reflects a genuine loss of detail in the corresponding recess of the
die face. This is shown by the absence of tumbling marks on the
surface of the bulge. Tumbling marks — abundant on most planchets —
should persist in any area not contacted by the dies.
For the longest time, the featureless bulge of this and other
specimens provided a handy excuse as to why the split couldn’t be seen
in the center of the coin. One could argue that there wasn’t enough
striking pressure to force coin metal into the split. Or maybe the
split imperceptibly hugged one side of the bulge. Or perhaps the split
surrounded the zone of subsidence, converting it into a retained
interior die break. The oval shape of many subsidence zones seemed to
support the latter conjecture.
Braswell’s 5-cent coin undermines the general applicability of
these rationalizations. With eyes newly opened, a closer inspection of
the 1974-D Roosevelt dime reveals that a continuous split is unlikely
or at least questionable. The arm that arises at 6:00 tapers to a
point before it disappears.
Diagnosing a median split die has now become a complicated
procedure that may not always yield a clear answer. If the split is
continuous or phenomenally wide, diagnosis is simple. In all other
cases, a series of questions must be asked concerning the paired arms
and the gap that separates them. 1) Does the interruption coincide
with a central elevation? 2) What is the nature of that elevation? Is
it a die subsidence error, an interior die break, or a retained
interior die break? 3) Do the two arms follow one side of the central
elevation, surround the elevation or plunge into the elevation? 4)
Does either arm taper or pinch out as it approaches the center of the
coin? 5) Are the two cracks aligned with each other or offset? On
Braswell’s coin, the die crack on the left peters out as it enters the
top of Monticello’s staircase. The crack on the right is much higher
and pinches out almost halfway up the nearest column. 6) How wide is
the gap separating the facing tips of the two arms?
The close association between median split dies, radial antipodal
die cracks and die subsidence errors is meaningful but murky. At the
very least, it testifies to a hard, brittle die exterior and an
abnormally soft interior. Both probably stem from faulty heat
treatment (e.g., tempering, quenching).
It may be that the die sinks in first. This might increase stress
on the surrounding donut of die steel that has to absorb all of the
strike force. This, in turn, might generate a pair of opposing radial
cracks. Crack lengthening may stall upon reaching the zone of
subsidence, as the softer die steel may interfere with crack propagation.
One flaw in this proposed sequence is that I’ve not yet
encountered the first stage — a crack-free coin with a centrally
located zone of subsidence. It may instead be that the two defects
appear simultaneously or that crack formation precedes the sinking-in
of the die face. I have seen radial die cracks — some as long and as
wide as those seen in Braswell’s coin — appear in otherwise
normal-looking dies. However, I have encountered wide radial die
cracks in dies that did not sink in. One example is shown in a 1993
Right now, unless a median split die is phenomenally wide, or is
uninterrupted, the diagnosis is uncertain. It may instead be a pair of
radial die cracks.
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