A hydrous iron oxide, α-FeO(OH), which forms a series with lepidocrocite, γ-FeO(OH); sp. gr. 4.0; hardness 5; reddish-brown; massive or earthy; occurs as an alteration product of iron-bearing minerals in association with limonite or hematite. It is named after J. W. von Goethe (1749–1832).