Noun
English Wikipedia has an article on:bog ironWikipedia
bog iron (uncountable)
(geology) deposits of mixed oxides and hydroxides of iron formed when iron-bearing groundwater emerges onto the surface
However most iron as well as its forging was of domestic origin, probably from bog iron. Source: Internet
Iron ore was available throughout the country, including bog iron extracted from the ore in peat bogs in the north, the natural iron-bearing balls found in the Veluwe and the red iron ore near the rivers in Brabant. Source: Internet