Ammonium iron(III) sulfate

Molecular formula:
Chemical compound:
ammonium iron(III) sulfate pentahydrate
Common name:
iron alum

NH4Fe(SO4)2 * 12H2O – ammonium iron(III) sulfate – is a weakly-violet or white crystalline solid. It is also known as ferric ammonium sulfate or iron alum. It forms crystals together with 12 water molecules. In the air, this water slowly evaporates and the compound acquires a yellowish tint. It is used in tanning for its ability to alter the protein structure of skin. In the textile industry, it is used to chemically mill cotton and wool fabrics and yarns. In jewelry, some pastes with iron alum are used to clean products containing precious metals.


Hazard information

Hazard statements

  • Causes serious eye damage.
  • May be corrosive to metals.

Precautionary statements

  • Wear protective gloves/protective clothing/eye protection/face protection.
  • IF IN EYES: Rinse cautiously with water for several minutes. Remove contact lenses if present and easy to do – continue rinsing.