Iron(III) 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.
Molar mass：207.90 g/mol
Solubility in water：very slightly soluble
This is a relatively unstable artificial product that does not occur in nature.