The March 18 Collectors’ Clearinghouse was dedicated to
clad-composition coins struck on isolated copper cores. Such errors
occur when both clad layers separate from the core after blanking but
before the strike. These coins are severely underweight and usually
show a weak strike.
It is theoretically possible to stumble upon a
full thickness, full diameter, pure copper dime or quarter dollar.
Such an error would trace back to the bonding mill, when the two
copper-nickel clad strips and the copper core strip are fed between
the rollers together for the first time.
If the core strip protrudes beyond the
flanking clad strips at the leading or trailing end of the composite
strip, it will be rolled to coin thickness during subsequent passes
through the rolling mill. If the dangling pure copper segment is not
trimmed away, it will enter the blanking press and any blank punched
out of it will weigh the same as a normal blank (2.27 grams for a dime
and 5.67 grams for a quarter dollar).
None seen so far
I have not yet encountered a genuine example
of such a coin. I do not believe any have been authenticated. Yet many
coins are bought and sold under the impression that they belong to
this rare category of planchet error. The majority of fraudulent
specimens are simply normal coins that have been plated with copper
outside the Mint.
Shown here is a 1974 Washington quarter dollar
that weighs 5.63 grams and that was plated with copper before being
crudely engraved with the letter Q. The coin was subjected to X-Ray
Fluorescence Analysis by John Lorenzo using an EDAX-Orbis Micro-XRF
Elemental Analyzer. This machine records a pooled average of metallic
elements present in the upper 10-50 microns (depth of penetration
depends on the alloy).
Results were 93 percent copper, 5 percent
nickel and 2 percent zinc (the last is a common contaminant in
copper). For a normal quarter dollar, the values should be 75 percent
copper and 25 percent nickel.
Nickel’s presence telling
More than a trace amount of nickel in a “pure
copper” coin is a possible indicator that the coin is plated with
copper. (The X-ray beam passes through the copper plating and picks up
readings from the underlying copper-nickel). Conclusive proof of this
was obtained some time earlier when I took a scalpel and shaved away a
portion of the reverse design rim. The silvery glint of underlying
copper-nickel was immediately exposed.
Lorenzo analyzed a series of copper-plated 5-,
10- and 25-cent coins (a total of eight pieces). Copper percentages
ranged from 83 percent to 93 percent and nickel percentages ranged
from 5 percent to 15 percent. I’m told the observed variation is due
to variable thickness of the copper plating.
Our next coin, a 1972-D Roosevelt dime,
managed to fool many experts (including me). It weighs 2.24 grams and
initially didn’t seem to be plated. I scraped away at the reverse
design rim and exposed only copper. Both surfaces are flecked with
gray metal. XRF analysis produced readings of 87 percent copper, 11
percent nickel and 2 percent zinc. I toyed with the weird idea that
this dime was composed of nickel or copper-nickel bits embedded in a
copper matrix. However, before going to press I decided to dig more
deeply into the rim with my scalpel. This final attempt revealed
A second population of full-thickness copper
dimes and quarter dollars consists of coins struck on counterfeit
copper planchets by a pair of counterfeit dies. These coins are
sometimes mass-produced, plated with silver and placed into
circulation. Other, higher-quality pieces are sold directly to
unsuspecting collectors as off-metal errors.
Microscopic inspection of the accompanying
1981-D Washington quarter dollar shows crude workmanship. This piece
was undoubtedly fabricated as a circulating counterfeit. It weighs in
at a slightly elevated 5.76 grams and was only partly plated with
silver. The area not covered by silver registers XRF values of 96
percent copper, 2 percent nickel, and 2 percent zinc. The plated area
produces values of 72.4 percent copper and 23.2 percent silver.
A far more convincing copper counterfeit is
represented by a 1966 quarter dollar that weighs 5.76 grams. The
strike is sharp and the reeding properly spaced. The copper percentage
at the surface is 96.4 percent. Nickel (1.4 percent) and zinc (2
percent) comprise the remaining elements. The key warning sign is a
loosely adherent bit of excess copper found on the reverse face (not
shown) that was originally decorated by a poorly defined olive leaf.
This is not a lamination error and it clearly stood above the field
before I removed most of it. (Invasive tests like this should only be
performed if you’re pretty sure your off-metal coin is fake or if it
has already been damaged.)