So you know how if you've been handling coins you get that distinctive whiff of metal? Or how the water from the fountain in the back end of your elementary school tasted pretty much like the smell of those coins? You were wrong—metal has no smell.
According to a Nature news article about a recent study in the famous Angewandte Chemie Internation Edition, what we think of as the smell of metal is actually the smell of our own body. When we come into contact with metal, it catalyzes reactions among the slime of organic molecules that coats our bodies. When skin oils are exposed to iron and copper they can produce smelly aldehydes and ketones; for instance, touching iron can produce the ketone 1-octen-3-one, which has a mushroom-like, metallic odor (which, I'm guessing, can't be good).
One thing (among many) that seems weird to me about this is that I could swear that I've smelled metal that hasn't touched my skin or the skin of someone near me. Maybe it's possible that someone touched it in the past and although they're long gone, their fetid, decomposing skin oils linger on. Or maybe that's an effect of being an animal—unlike, say a dog—that usually brings smellable items up to the nose rather than the other way around.
(Via The Daily Grail)