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Iron(II) Sulfide

Iron(II) sulfide, also popular as iron sulfide or ferrous sulfide, is an inorganic, water-insoluble compound represented by the chemical formula FeS [1, 2]. In IUPAC nomenclature, it is called sulfanylideneiron [1]. It naturally occurs as the minerals troilite and pyrrhotite [3]. FeS has the nickel arsenide structure, with trigonal prismatic sulfides and octahedral iron centers [5].

Iron(II) Sulfide Identification

CAS Number 1317-37-9 [1]
PubChem CID 14828 [1]
ChemSpider ID 8466211 [2]
EC Number 215-268-6 [1]
MDL Number MFCD00011013 [1]

Iron(II) Sulfide Formula

Iron(II) Sulfide Composition and Synthesis

When iron and sulfur are mixed and heated in a test tube, it undergoes an exothermic reaction to produce iron(ii) sulfide [6].

Fe + S → FeS

Iron(II) Sulfide

Reaction with Hydrochloric Acid

Iron sulfide reacts with hydrochloric acid to yield ferrous chloride and hydrogen sulfide, as indicated by the following reaction:

FeS + 2 HCl → FeCl2 + H2S

Properties and Characteristics of Iron(II) Sulfide

General Properties

Molar Mass/Molecular Weight 87.905 g/mol [1]

Physical Properties

Color and Appearance Gray to brownish-black rods, lumps, or granular powder, colorless when pure [1]
Odor Odorless [8]
Melting Point 1194 °C, 2181 °F [1]
Boiling Point  Decomposes [1]
Density 4.75 g cm-3 [1]
State of matter at room temperature Solid [1]
Solubility Reacts in acids with the production of hydrogen sulfide, insoluble in nitric acid [1]
Solubility in Water 0.00062 g/100 cc at 18 °C [1]
Magnetic Susceptibility (χ)  1074 X 10-6 cm3/mol

Atomic Properties

Crystal Structure Octahedral

Iron(II) Sulfide Structure


  • As a pigment in ceramics, hair dyes, and glass containers [1, 7].
  • Treating exhaust gases and lessening heavy metal pollution [1].
  • To synthesize hydrogen sulfide in the laboratory [1].

Is It Safe

Iron sulfide can cause irritation to your skin, eyes, lungs, and gastrointestinal tract when inhaled [1]. It is known to cause slight toxicity upon ingestion [8].


  1. Ferrous Sulfide –
  2. Iron(II) Sulfide –
  3. Ferrous Sulfide –
  4. Iron(II) Sulfide –
  5. Structures Related to NaCl and NiAs –
  6. Iron and Sulfur Reaction –
  7. Iron(II) Sulfide –
  8. Iron(II) Sulfide –

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