Iron can burn Under normal conditions,
the oxidation rate of iron depends strongly on its form: a simple piece of metal does not burn, but thin fibers of iron or fine powder can easily be ignited.
It all depends on the contact surface of the iron with the air: it should be enough so that the oxidation reaction can sustain itself.
Iron wool consists of fairly
thin fibers of iron. Oxidation on such a surface produces enough heat to keep the reaction going, and it runs "on its own”.
