Ferric hydroxide

Iron(III) oxide-hydroxide or ferric oxyhydroxide is the chemical compound of iron, oxygen, and hydrogen with formula FeO(OH). Iron(III) oxide-hydroxide or ferric oxyhydroxide is the chemical compound of iron, oxygen, and hydrogen with formula FeO(OH). The compound is often encountered as one of its hydrates, FeO(OH)·nH2O. The monohydrate FeO(OH)·H2O (CAS 51274-00-1, C.I. 77492) is often referred as iron(III) hydroxide Fe(OH)3, hydrated iron oxide, yellow iron oxide, or Pigment Yellow 42. Anhydrous ferric oxyhydroxide FeOOH occurs naturally as four different minerals (polymorphs) denoted by the Greek letters α, β, γ and δ.