What is "limonite"

Limonite \Li"mon*ite\ (l[imac]"m[o^]n*[imac]t), n. [Gr. leimw`n any moist grassy place, a meadow: cf. F. limonite, G. limonit.] (Min.) Hydrous sesquioxide of iron, an important ore of iron, occurring in stalactitic, mammillary, or earthy forms, of a dark brown color, and yellowish brown powder. It includes bog iron. Also called brown hematite.

n. (context mineralogy English) any of several natural hydrous iron oxides; often a mixture of goethite and hemite with clays and manganese oxide

n. a widely occurring iron oxide ore; a mixture of goethite and hematite and lepidocrocite

Limonite 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)·nHO, although this is not entirely accurate as the ratio of oxide to hydroxide can vary quite widely. Limonite is one of the two principal iron ores, the other being hematite, and has been mined for the production of iron since at least 2500 BCE.