Iron(III) sulfide
Iron sulfide, also known as ferric sulfide or sesquisulfide, is one of the three iron sulfides besides FeS and FeS2. It is a solid, black powder but decays at ambient temperature into a yellow-green powder.
This is a relatively unstable artificial product that does not occur in nature.Reactions
Iron sulfide decays at a temperature over 20 °C into iron sulfide and elemental sulfur:
With hydrochloric acid it decays according to the following reaction equation:
