is an iron ore consisting of a mixture of hydrated iron(III) oxide-hydroxides in varying composition. The generic formula is frequently written as FeO(OH) · nH2O, although this is not entirely accurate as the ratio of oxide to hydroxide can vary quite widely.
Streak: Yellowish brown
Specific gravity: 2.9–4.3
Density: 2.7–4.3 g/cm3
