Mohr's Salt

Formula: (NH4)2Fe(SO4)2·6H2O Mohr's salt Double sulfate of divalent iron and ammonium. Naturally occuring, it is known as mineral mohrite.


  • Crystal system: monoclynic
  • Crystal shape: from pure solution, flat tabular crystals are growing. If solution is conpaminated with Fe3+ ions, then crystals becoming more elongated.
  • Color: green
  • Stability on air: stable, a rare example of stable Iron (II) compound.


Dissolve equimolar amounts of ammonium sulfate ((NH4)2SO4) and iron (II) sulfate (FeSO4·7H2O) in water with small amount of sulfuric acid, then crystallize.


I used regular evaporation method. On air, solution is prone to slow oxidation, addition of small amount of sulfuric acid suppresses it.


The compound is generally safe, though can ittirate skin.

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Mohr's salt

Mohr's salt

Mohr's salt

Mohr's salt

Mohr's salt