the orion nebula (at least the part we can see) is not very old (yet). while several hot, massive stars have had a chance to form in the nebula, none of them has been around long enough to go supernova. so relative to supernova remnants, and other areas where the gasses have been 'mixed' with the wreckage from exploded stars, what can you say about the iron levels you'd expect to see in the orion nebula?