Iron DOES react to a flame test. According to the "handbook for prospectors and operators of small mines" the effect of oxy-gas flame on iron is: "ignites.sparkles;dark oxides". Are you certain that you are performing the test correctly ?
sparks from yellow to blue
putek!
The elements contained in this molecule are not able to give a color in the flame.
Its electrons are excited to a higher energy state in the flame, and then they immediately release that energy, which is visible as yellow light.
Ammonia is limit test of iron because it is a chemical. Ammonia is a very story chemical.
Iron has a yellow-gold color in the flame test.
All sodium salts will give a yellow flame test, because of the metal sodium in the compounds.
It is not the anions (e.g. iodide) that are responsible for the flame test color, rather the cations such as sodium ion, potassium ion and calcium ion give you different colors.
sparks from yellow to blue
A goldisf color.
The color of the flame test is specific for some metals. See the link below.
Bright yellow :: This is the sodium ions. Any sodium compound will give a flame test colour of yellow/
Blue
Pink
nitrogen
putek!
Iron is a sort of sparkly-black when it is burned.