limonite

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. [ 1913 Webster ]