Why is fes unaffected by metal?

Fes, or iron(II) sulfide, is generally unaffected by metals because it is a compound formed from iron and sulfur, which do not readily react with other metals under normal conditions. The stability of the iron-sulfur bond in FeS makes it resistant to displacement reactions that might occur with more reactive metals. Additionally, the specific chemical properties of FeS contribute to its inertness in metal-rich environments.