Penny-wise -- Juniata College professor finds research on copper, coins makes perfect cents
Arizona Coin Collector
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Penny-wise -- Juniata College professor finds research on copper, coins
makes perfect cents
By Cori Bolger, cbo...@altoonamirror.com
POSTED: October 13, 2008
HUNTINGDON - If someone gave Ryan Mathur a penny for his
thoughts, they would learn much more than they bargained
for.
Mathur, an associate professor of geology at Juniata
College, is the first researcher to discover that tracing
the copper used in U.S. pennies correlates directly to
the mine that produced the metal.
He plans to publish his findings in the Journal of
Archaeological Science in November.
''I like pennies and I like copper, so when I was
studying the geology of copper deposits, it dawned on
me that I should look at pennies and it would tell me
where they came from,'' said Mathur, a Huntingdon
resident. ''It was a natural fit.''
Mathur, who also is a coin collector and a geologist
specializing in copper ore deposit research, said
copper has two isotopes that give off distinct ''
geo-chemical signatures'' depending on the ratio of
each isotope the ore deposit was taken from.
''The way they form, whether it's close to a volcano
or through a process like weathering, gives them
different signatures and allows us to see differences
between them,'' he said.
Like many Americans, he just happened to have a
penny in his pocket.
He tested that penny - and several others - and
discovered that the copper in the pennies minted in
the 19th and 20th century came from a single source
with a specific signature.
Mathur decided to trace the copper in historic
pennies to see if he could match the penny to the
deposits where the copper originated.
He cut a sample from the penny - defacing currency
in the name of science - and dissolved a portion of
the copper in acid.
Mathur then suspended it in a solution and used a
mass spectrometer from the University of Arizona to
obtain the signature of the metal.
''This is important because we've only had the
ability to measure copper isotopes reliably in the
past 16 or 17 years, and that's relatively recent
in science terms,'' Mathur said.
At the same time, he had to research the origins of
copper bought by the U.S. government during the
course of American history.
He delved into the Archives of the U.S. Mint in
Philadelphia and found that from 1810 to 1981, 95
percent pure copper was used to mint pennies.
Copper used to mint pennies from 1810 to 1835 came
from a site in Cornwall, England.
From 1835-44, the U.S. government bought copper
from a variety of sources. Starting in 1845, most
of it came from a giant deposit in Michigan.
Then, in 1872, the U.S. began purchasing copper
from sources around the world as a way to protect
domestic resources. The government later returned
to using copper from Montana and Arizona, Mathur
said.
To make the link between currency and the copper
site, Mathur spent $150 to purchase an 1810 penny
from a Huntingdon coin dealer.
Then he hunted down a sample from the Cornwall mine
at the Carnegie Museum of Natural History in
Pittsburgh.
''We're delighted anytime someone can make
important discoveries using our collection,''
said Ellen James, museum spokeswoman. ''That's
definitely one reason we're here, to further
people's research.''
By separately testing the penny and the deposit
sample, Mathur found their signatures lined up.
Mathur also traced pennies minted in Denver to
the Anaconda mine in Butte, Mont., and other
domestic deposits.
Using identifying signatures from ore deposits
can be applied to any object made from or
containing copper to see if that copper
originated at those sites, Mathur said.
''This type of application to archaeological
items is just starting, so I wanted to establish
the technique,'' he said.
Mathur, who financed most of his project himself,
likes to joke that he spent $500 on 50 cents
worth of pennies for his research. He is now in
the process of writing grants to secure funding
from sources other than himself.
''If other researchers use my methods, it means
I've started something and got people motivated
and thinking in a different way,'' he said.
Mirror Staff Writer Cori Bolger is at 946-7458.
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