Iron stain is the classic method for demonstrating iron in tissues. Hemosiderin (storage iron granules) may be present in areas of old hemorrhage or be deposited in tissues with iron overload. Prussian blue stain is used for the demonstration of ferric iron in the tissue sections. This stain can aid in identifying hemochromatosis and hemosederosis where abnormal large deposits of iron may be seen. In the prussian blue staining, the sections are treated with an acidic solution of potassium ferrocyanide and any ferric iron present reacts to form an insoluble bright blue pigment called Prussian blue.

http://purl.obolibrary.org/obo/NCIT_C23016

Iron Staining Method