It has often irked me that metals eg coins, old kitchen knife can have
such a strong smell, when they surely can’t actually be vapourizing at
room or body temperature?
Dietrich and Glindemann at Virginia Tech explain that the odour
results from a metal induced oxidation of lipids eg on the skin. The
compounds people smell are actually aldehydes and ketones, and not any iron containing compounds.
The same metallic odor is produced if you rub blood on skin, so the
researchers speculate that the ability to smell blood sensitively would be an evolutionary advantage that allowed early humans and their animal ancestors to track wounded prey.
One of the products produced when skin comes in contact with metal is octeneone (OEO). Humans can smell OEO at concentrations as low as 5 parts per trillion, which indicates humans are highly evolved for
detecting this compound.
Read more at: http://phys.org/news82229855.