Unique errors often pose a diagnostic challenge because there are no
precedents to consult. Such is the case with a 1972-D Jefferson 5-cent
coin recently sent to me by veteran error collector Steve Mills. A
curved (concave) clip in the northwest quadrant is flanked by an
unexpected curved groove. The clip shows such hallmarks of
authenticity as metal flow in adjacent design elements (like the E of
WE) and weakness of the design rim at the pole opposite the clip (the
The groove was clearly present before the strike because its margins
are flush with the field and design and it widens and narrows in
concert with the topography that it crosses.
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Mills speculated that the groove could be an incomplete clip
(incomplete punch). The problem with this idea is that the groove
appears on only one face while an incomplete clip always appears on
both faces. This is because one punch mark is generated by the
blanking die and the other by a hole in a perforated base plate.
Another difficulty with the incomplete clip theory is the failure of
the groove to appear on the coin’s edge. An incomplete clip penetrates
the surface of the strip, and all but the shallowest will be visible
on the edge of the affected blank.
A much more satisfactory interpretation identifies the groove as a
novel form of blanking burr. For some reason, as the blanking die
sliced through the strip, it produced a burr along the bottom edge of
the hole. When this hole was sliced though again by a blanking die to
create the clipped blank, the burr remained attached. Later on, during
its rough-and-tumble journey to the press, the blanking burr was
pushed over onto the surface of the blank. The burr was eventually
struck into the coin by the 5-cent obverse die.
There is considerable evidence to support this theory. Whenever a
piece of metal is struck into a planchet, it is outlined by a fissure,
which is here represented by the curved groove. We can see this effect
in association with a more familiar form of blanking burr, the
A rolling fold is a blanking burr that protrudes from the blank
(rather than the hole), and is thought to be the result of a chipped
or locally dulled blanking die. The burr is folded over onto the
surface of the planchet during upsetting and is struck into the
surface of the coin in the form of a short broad symmetrical tongue of
metal. A typical rolling fold, along with its fissure, is shown here
on a Washington quarter dollar.
A different kind of burr
Another type of burr is often found in association with straight
clips, like the one shown here. Paralleling the straight edge is a
fissure that, except for its linear shape, closely resembles the
fissure on the 1972-D Jefferson 5-cent coin. It most likely represents
a cutting burr generated when the leading or trailing end of the strip
was trimmed by a saw or guillotine. Sometime after the blank was
punched out from the end of the strip, the burr was pushed over onto
the surface of the planchet and was eventually struck into the coin.
These straight fissures used to be incorrectly identified as
“incomplete straight clips.”
Other ideas include scars from a guide or stop, but these
explanations seem less likely.
Returning to the 1972-D Jefferson 5-cent coin, we find additional
evidence supporting the blanking burr theory.
The edge of the clip shows only vertical striations; it lacks the
more familiar cut-and-tear texture generated as the blank tears away
from the bottom of the strip as it’s pushed through by the blanking
die. The edge texture suggests that, instead of stopping just short of
the bottom surface, the blanking die traveled all the way through the
strip, possibly dragging some metal along with it.
The edge of a curved clip should be vertical in cross section. But
here, the edge is slightly inclined, tilting outward as one approaches
the obverse face. This effect can be attributed to the extra thickness
added to the planchet by the pushed-over burr.
Exactly why the burr formed isn’t clear. Perhaps the blanking die
was dull, or perhaps the blanking die pushed ahead of it the roughened
metal of a breakaway zone that protruded inward to an unusual degree
from the side of the hole.