from which metallic iron
can be economically extracted. The ores
are usually rich in iron oxides
and vary in color from dark grey, bright yellow, deep purple, to rusty red. The iron itself is usually found in the form of magnetite
(, 72.4 e), hematite
(, 69.9 e), goethite
(, 62.9 e), limonite
(, 48.2 e).