Peripheral smear from a patient with a history of sickle cell anemia. The arrows indicate hypochromic erythrocytes containing clusters of small irregular granules around the periphery of the red blood cell. These granules, composed of ferric iron, are called siderotic granules and appear as dark-blue granules in Wright stain. To verify that the red cell inclusions contain iron, it is necessary to use an iron stain such as Prussian blue.