Iridium is characterized by a higher melting point than either nickel or platinum.
Therefore, it wears very well when subject to electrical discharge. However, at high temperatures it oxidizes a little too much and so we are unable to use pure iridium for spark plug electrodes. The following photographs compare the durability of the new iridium alloy and pure iridium when used in an engine under the same conditions. Part of the pure iridium material was shed and corroded.