Fe3[Fe(CN)6]2, known as Prussian blue, is a complex compound made up of iron and cyanide ions. It consists of three iron (Fe) ions and two hexacyanoferrate (Fe(CN)6) ions. This compound is notable for its deep blue color and is often used as a pigment in paints and dyes. Prussian blue has applications in various fields, including art, medicine, and environmental science. In medicine, it is used as an antidote for certain types of heavy metal poisoning, while in environmental science, it can help in the removal of radioactive cesium from contaminated water.