Iron(II) sulfide


Iron(II) sulfide or ferrous sulfide (Br.E. sulphide) is one of a family chemical compounds and minerals with the approximate formula FeS. Iron sulfides are often iron-deficient non-stoichiometric. All are black, water-insoluble solids.

Iron(II) sulfide
Strukturformel Nickelarsenid.png
Sample of iron(II) sulfide
Other names
Iron sulfide, ferrous sulfide, black iron sulfide, protosulphuret of iron
  • 1317-37-9 checkY
3D model (JSmol)
  • Interactive image
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ECHA InfoCard 100.013.881 Edit this at Wikidata
  • 10290742
  • TH5J4TUX6S checkY
  • DTXSID5061665 Edit this at Wikidata
  • InChI=1S/Fe.S/q+2;-2 checkY
  • InChI=1/Fe.S/q+2;-2
  • [Fe+2].[S-2]
Molar mass 87.910 g/mol
Appearance Grey, sometimes in lumps or powder
Density 4.84 g/cm3
Melting point 1,194 °C (2,181 °F; 1,467 K)
negligible (insoluble)
Solubility reacts in acid
+1074·10−6 cm3/mol
Occupational safety and health (OHS/OSH):
Main hazards
Source of hydrogen sulfide, can be pyrophoric
NFPA 704 (fire diamond)
Related compounds
Other anions
Iron(II) oxide
Iron(II) selenide
Iron(II) telluride
Other cations
Manganese(II) sulfide
Cobalt(II) sulfide
Related Iron sulfides
Iron(III) sulfide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Preparation and structureEdit

FeS can be obtained by the heating of iron and sulfur:[1]

Fe + S → FeS

FeS adopts the nickel arsenide structure, featuring octahedral Fe centers and trigonal prismatic sulfide sites.


Iron sulfide reacts with hydrochloric acid, releasing hydrogen sulfide:[2]

FeS + 2 HCl → FeCl2 + H2S
FeS + H2SO4 → FeSO4 + H2S

In moist air, iron sulfides oxidize to hydrated ferrous sulfate.

Biology and biogeochemistryEdit

Iron sulfides occur widely in nature in the form of iron–sulfur proteins.

As organic matter decays under low-oxygen (or hypoxic) conditions such as in swamps or dead zones of lakes and oceans, sulfate-reducing bacteria reduce various sulfates present in the water, producing hydrogen sulfide. Some of the hydrogen sulfide will react with metal ions in the water or solid to produce iron or metal sulfides, which are not water-soluble. These metal sulfides, such as iron(II) sulfide, are often black or brown, leading to the color of sludge.

Pyrrhotite is a waste product of the Desulfovibrio bacteria, a sulfate reducing bacteria.

When eggs are cooked for a long time, the yolk's surface may turn green. This color change is due to iron(II) sulfide, which forms as iron from the yolk reacts with hydrogen sulfide released from the egg white by the heat.[3] This reaction occurs more rapidly in older eggs as the whites are more alkaline.[4]

The presence of ferrous sulfide as a visible black precipitate in the growth medium peptone iron agar can be used to distinguish between microorganisms that produce the cysteine metabolizing enzyme cysteine desulfhydrase and those that do not. Peptone iron agar contains the amino acid cysteine and a chemical indicator, ferric citrate. The degradation of cysteine releases hydrogen sulfide gas that reacts with the ferric citrate to produce ferrous sulfide.

See alsoEdit


  1. ^ H. Lux "Iron (II) Sulfide" in Handbook of Preparative Inorganic Chemistry, 2nd Ed. Edited by G. Brauer, Academic Press, 1963, NY. Vol. 1. p. 1502.
  2. ^ Hydrogen Sulfide Generator
  3. ^ Belle Lowe (1937), "The formation of ferrous sulfide in cooked eggs", Experimental cookery from the chemical and physical standpoint, John Wiley & Sons
  4. ^ Harold McGee (2004), McGee on Food and Cooking, Hodder and Stoughton