Iron sulfide

Iron sulfide or Iron sulphide can refer to range of chemical compounds composed of iron and sulfur.

Minerals
By increasing order of stability:
 * Iron(II) sulfide, FeS
 * Greigite, Fe3S4 (cubic)
 * Pyrrhotite, Fe1−xS (where x = 0 to 0.2) (monoclinic or hexagonal)
 * Troilite, FeS, the endmember of pyrrhotite (hexagonal)
 * Mackinawite, Fe1+xS (where x = 0 to 0.1) (tetragonal)
 * Marcasite, orthorhombic FeS2
 * Pyrite, cubic FeS2 (fool's gold)
 * Arsenopyrite (mispickel), FeAsS, or Fe(As-S), Fe(III) mixed arseno-sulfide (monoclinic)

Synthetic

 * Iron(III) sulfide, Fe2S3
 * Iron-sulfur clusters, includes both synthetic and biological

Biological

 * Iron–sulfur protein