Friday, May 11, 2007

Coins Don't Smell, You Do... or Do You?

This evening, Lori alerted me to an article she found at "weird science" on MSNBC --

She tried to tease by asking, "why do you get that odor when you touch coins?," to which I quickly answered, "a chemical reaction."

Her follow-up surprised me more: It's from iron in the coins!

Here's the article text at msnbc:
"That metallic odor you smell after handling change? It's created by the breakdown of oils in skin after touching objects that contain iron. The chemical reaction has most of us running to wash our hands to get that musty scent out."

As any numismatist surely knows, there's no iron in US coinage, nor much of anywhere else. Most of our coins are made from an alloy of copper and nickel. the penny is mostly zinc (since the early 1980's, prior to that it was mostly copper), and the golden dollar contains manganese in addition to copper, nickel and zinc. I had an amazing experience a couple months ago, in which I spotted a rack full of pre-1971 half dollars at the teller's station of the local bank (after the teller explained that a customer had brought them in along with a few Eisenhower dollars to exchange for bills after finding them in a home piggy bank, I immediately bought all 17 of the 40% and 90% silver coins, for face value!), but other than that I haven't seen silver in circulation recently. Of course, in 1943 pennies were made of steel, but I haven't seen a steel penny in circulation since I was a child.

The msnbc article was sourced from Live Science, at That article has an author, by the name of Ker Than, and quotes "study team member Dietmar Glindemann of the University of Leipzig in Germany."

As it happens, the 1, 2 and 5 eurocent coins are mostly steel, though each of those coins has a copper coating. So, even in Europe, there is no contact with an iron-based substance. And, if specific to European coinage, one would hardly know by the uncritical re-printing of the story by sources such as msnbc and foxnews.

Interesting, though, I found in Discover Magazine a variant of the story, this time more plausibly linking the odor to a reaction to copper, not iron. The story quotes "Virginia Tech organic chemist Dietmar Glindemann," apparently newly arrived from Leipzig.

So I've written notes to Mr. Than and Dietmar Glindenmann; it should be fun to see what they have to say.

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