( crystals )
Ferric Ammonium Sulfate is a common Iron compound with a wide range of industrial uses from serum cholesterol determination to textile dyeing.
It is in the form of large purple crystals that resemble Amethyst.
In chemistry demonstrations, Ferric Ammonium Sulfate is used in some classic experiments.
The most common is when solutions of Ferric Ammonium Sulfate and Sodium Ferocyanide are mixed together. This produces Prussian Blue, a deep blue color dye used extensively in inks. Added to a solution of Sodium Silicate, Ferric Ammonium Sulfate crystals will 'grow' and make the well-known 'Chemical Garden'.
( Material Safety Data Sheet )