Magnetite or magnetic iron ore, specular iron, and limonite are also oxides of iron.
"Geology"
James Geikie
In a similar way, too, human remains in parts of Florida have, through the infiltration of water charged with iron, become partially converted into limonite iron ore; and yet we know that these bones have been buried within quite recent times.
"Animals of the Past"
Frederic A. Lucas
For instance, carbon dioxide of the atmosphere has been added to lime and magnesia of the igneous rocks to make calcite and dolomite, water has been added to some of the alumina and silica of the igneous rocks to make kaolin or clay, and both oxygen and water have been added to the iron of the igneous rocks to make limonite.
"The Economic Aspect of Geology"
C. K. Leith