Lake Ore

(also bog iron ore), iron ore of lacustrine origin consisting of hydrated iron oxides (limonite) with various impurities (Mn₂O₃, P₂O₅). The Fe₂O₃ content may be as much as 68 percent. Lake ore is formed when the iron and manganese carried by rivers and groundwater are deposited on the bottom of lakes and swamps as hydrated iron oxides (powder, pea ore, bean ore, cakes of ore, or occasionally solid crusts). The ore usually occurs in separate sections and strips in the form of seams, interlayers, and lenses; the thickness of the deposits ranges from several cm to 2–3 m. The ore is not important commercially.