Scientists have sniffed out the reason for the musty, "metallic" odor you smell after handling coins or touching metal objects.

A new study finds that the smell of iron is, ironically, a type of human body odor, created by the breakdown of oils in skin after touching objects that contain the element.

"That we are smelling the metal itself is actually an illusion," said study team member Dietmar Glindemann of the University of Leipzig in Germany.

In an experiment, seven test subjects reported smelling the metallic odor after their hands came into contact with iron. Researchers took gas samples from the subjects' skins and traced the smell to 1-octen-2-one, an organic molecule formed when certain oils in skin decompose.

Scientists think it works like this: When touching objects made of iron, perspiration from skin causes the iron atoms to gain two electrons. The doubly negative iron atoms react with oil in skin, causing them to decompose, forming 1-octen-2-one.

Because blood contains iron, rubbing blood over skin produces a similar metallic smell, the researchers said.

"That humans can 'smell' iron can be interpreted as a sense for the smell of blood," Glindemann said.