Iron(II,III) sulfide

Iron(II,III) sulfide is a blue-black (sometimes pinkish^{[citation needed]}) chemical compound of iron and sulfur with formula Fe₃S₄ or FeS·Fe₂S₃, which is much similar to iron(II,III) oxide. It occurs naturally as the sulfide mineral greigite and is magnetic. It is a bio-mineral produced by and found in magnetotactic bacteria. It is a mixed valence compound, featuring both Fe²⁺ and Fe³⁺ centers, in 1:2 ratio.

Iron(II,III) sulfide

Names
Other names Ferrous-ferric sulfide, greigite
Identifiers
CAS Number	12063-39-7
3D model (JSmol)	Interactive image
ChEBI	CHEBI:86238
ChemSpider	34999896
PubChem CID	72720442
CompTox Dashboard (EPA)	DTXSID20923500
InChI InChI=1S/3Fe.4S/q+2;2*+3;4*-2 Key: UHUWQCGPGPPDDT-UHFFFAOYSA-N
SMILES [S-2].[S-2].[S-2].[S-2].[Fe+2].[Fe+3].[Fe+3]
Properties
Chemical formula	FeS·Fe2S3
Molar mass	295.805
Appearance	Bluish-black, pinkish
Density	4.049 g/cm3
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Y verify (what is YN ?) Infobox references

Crystal structure

The crystallographic unit cell is cubic, with space group Fd3m. The S anions form a cubic close-packed lattice, and the Fe cations occupy both tetrahedral and octahedral sites.^[1][2]

Crystal structure of iron(II,III) sulfide projected along the [110] direction

• 
  Emphasis on the SFe₄ tetrahedra.
• 
  Emphasis on the FeS₄ tetrahedra
• 
  Emphasis on the FeS₆ octahedra

Magnetic and electronic properties

Like the related oxide magnetite (Fe₃O₄), iron(II,III) sulfide is ferrimagnetic, with the spin magnetic moments of the Fe^III centers in the tetrahedral sites oriented in the opposite direction as those in the octahedral sites, and a net magnetization. Both metal sites have high spin quantum numbers. The electronic structure of greigite is that of a half metal.^[3][4]