In the May 8, 2000, “Collectors’ Clearinghouse” column, a new type
of planchet error was assigned to a 1997-P Roosevelt dime struck on an
underweight (1.85 grams), full-diameter, solid copper-nickel planchet
(see photos). Veteran error/variety investigator Mike Ellis decided
that it had been struck on a “coreless” or “pure-clad” planchet.
The U.S. Mint wasn’t striking any foreign coins at the time, so
Ellis reasoned that this off-metal planchet emerged from a mishap in
the bonding mill, a mechanism that assembles the clad sandwich from
which dime blanks are punched. Finished dime strip is composed of a
relatively thick layer of pure copper surrounded by two thinner layers
of 75 percent copper and 25 percent nickel. These are the clad layers
or cladding. A dime blank weighs around 2.27 grams. Each clad layer
weighs approximately 0.4 gram while the core weighs around 1.47 grams.
The core strip and the two clad strips are substantially thicker
when they are first fed into the bonding mill. The three strips are
fused together under high pressure between two rollers. Subsequent
rolling reduces the thickness of the composite strip to coin thickness.
To explain the solid copper-nickel composition of the 1997-P
Roosevelt dime, Ellis surmised that the core strip ran out prematurely
and that the two layers of cladding were forced together. The problem
with this scenario is that the double layer of cladding should
eventually have been reduced to dime thickness (yielding a blank of
normal weight). However, it’s possible that the core and one clad
strip ran out prematurely and the solid copper-nickel planchet was
derived from the trailing end of the other clad strip.
Verification of Ellis’ “coreless” diagnosis would require knowing
the precise thickness of clad strip prior to its entrance into the
bonding mill. To my knowledge such data has never been released by the
U.S. Mint or published in the numismatic literature.
In the absence of this critical data, it’s best to follow a
conservative strategy and classify the 1997-D dime as an “orphan
off-metal” error. Hardly a year goes by when the Mint doesn’t produce
at least some coins that fail to match the specifications of anything
it was producing at the time, domestically or under foreign contract.
One such coin — a 1996-D Washington quarter dollar struck on a nearly
full diameter, solid copper-nickel blank — was reported in the May 10,
2010, Clearinghouse column.
Confidence in the “missing core” explanation for the 1997-P dime
has eroded with the discovery of other full diameter, solid
copper-nickel dimes whose weights differ markedly from that first
specimen. In the September/October 2006 Errorscope, I reported on a
1992-D dime that weighed 2.51 grams — significantly more than a normal
dime. Since the density of a solid copper-nickel planchet is virtually
the same as that of copper-nickel clad planchet, this dime’s excessive
weight effectively rules out any “missing core” scenario, since even
improperly assembled dime strip would not be rolled to a thickness
greater than a dime blank.
Another full diameter, solid copper-nickel dime was recently
acquired in an eBay auction by a contact of mine (see photos). This
1974-D dime is quite thin and weighs 0.91 gram — over twice the weight
of a normal clad layer. Its specifications do not match anything the
Mint was producing in 1974 or any other year.
One feature suggests that at least this 1974-D example may warrant
a “missing core” diagnosis. The unstruck areas on the obverse face
show rough, parallel striations while the reverse face is smooth. The
microscopic appearance of the rough surface, and its presence on only
one face, is very similar to struck dime and quarter dollar clad
layers that I have in my collection. The rough surface is created by a
rotating descaling brush that cleans one side of each clad strip prior
to entry into the bonding mill.
Coin World’s Collectors’ Clearinghouse department does
not accept coins or other items for examination without prior
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Clearinghouse without prior permission will be returned unexamined.
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