On page 222 of the sixth edition of the Official Price Guide to
Mint Errors, released in 2002, author Alan Herbert provides a short
description of abnormally heavy, brassy-looking 1941 Lincoln cents. He
suggests that the cents were struck on planchets punched out of
foreign, possibly Peruvian stock.
I have seen many such cents and have provided here photos of one
of three examples residing in my collection. This example weighs 3.4
grams, which is in line with other pieces I’ve encountered (a normal
1941 cent should weigh 3.11 grams). The weights of these various
pieces range from 3.3 to 3.4 grams, which conform to the weight of 52
grains (3.37 grams) that Herbert cites. Herbert also mentions a rarer,
heavier subpopulation that weighs around 63 grains (4.08 grams), but I
have not encountered any of these.
Heavy, brassy cents, in the familiar weight range of 3.3 to 3.4
grams also occur in 1942, although they’re much rarer.
I’ve always been uneasy about the foreign stock scenario, so I
decided to send the illustrated cent to John Lorenzo for x-ray
fluorescence (XRF) analysis. Lorenzo is an expert on Colonial coins,
both silver and copper.
For his XRF analyses, Lorenzo uses a state-of-the-art Spectro
Midex Micro X-Ray Flourescence Spectrometer. Constituent metals are
measured to the nearest .001 percent. Solid-alloy pieces are best
suited to this technique, as the beam penetrates only 10 microns (10 µm).
Lorenzo offers his services to the entire collector community at a
price far below the major grading services. Prices vary, with bulk
orders receiving a discount. Lorenzo can be reached via email at email@example.com.
The analysis revealed the cent’s composition to be 86 percent
copper, 11 percent zinc and 3 percent tin. These numbers represent an
average of two readings (one on each face), with each number rounded
up to the nearest integer.
This composition does not resemble that of any foreign coin
produced by the U.S. Mint at any time in its history. Brass coins,
like those produced for Peru in 1942, have a lower percentage of
copper (70 percent), a higher percentage of zinc (30 percent) and no
tin. So the cent’s composition is unlikely to be of foreign stock or a
I doubt it’s an “orphan” off-metal error, as these tend to be
one-off events. The sheer number of these overweight, brassy cents
suggests that a significant length of strip or an entire coil was involved.
While the Mint did strike 1941 cents in experimental compositions
with normal dies, no records have been found for experiments in the
alloy used for my cent.
These three metals — copper, zinc and tin — are the normal
constituents of cents of this period. Normal cents are composed of 95
percent copper and 5 percent zinc and tin. However, sometimes these
constituents are mixed in the wrong proportions, producing an
“improper alloy mix” error.
The term “improper alloy mix” actually encompasses two different
errors: (1) planchets that have the wrong proportion of metals and,
(2) planchets with the right proportion of metals but with these
metals poorly mixed. Naturally, some errors combine both defects —
poorly mixed metals in the wrong proportions.
The prosaic explanation of an improper alloy mix is bolstered by
the fact that the year 1941 produced a bumper crop of normal-weight,
improper alloy mix cent errors. One example is shown here. The
zinc/tin fraction is represented by the lighter-colored streaks.
Like the first example shown here, many of the overweight, brassy
1941 Lincoln cents also show a streaky surface that is consistent with
an improper alloy mix error. Foreign brass coins seldom show such poor
mixing of the constituent metals.
As to why the cents are 0.2 gram to 0.3 gram overweight, this is
most likely due to the strip being rolled too thick. “Rolled-thick”
errors are a well-known error category that occurs when coin metal
strip is left a little too thick after final rolling. Among cents,
these errors can weigh up to 4.2 grams (and possibly more).
Rolled-thick errors can be found in many years. Shown here is a 1944
cent that weighs 4.2 grams. Heavyweight cents bearing this date were
once considered to have been struck on experimental planchets.
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