Limonite
Limonite (lī"mon*īt) , noun
[Greek leimw`n any moist grassy place, a meadow: compare French limonite, German limonit.]
(Mineralogy) 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.