Limonite is a general term for a mixture of fine-grained iron oxides, generally dominated by goethite, but also possibly containing hematite, lepidocrocite and other minerals. It forms from the weathering of other iron minerals, and may be precipitated by iron rich surface or ground water. It is a useful field term, and has been frequently used in the literature. The localities below have been described as containing limonite, but the sources do not give enough information to determine exactly which minerals are present.