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Wikipedia There is more information available on this subject at Iron (Material) on the English Wikipedia.
Iron ore - no label

A segment of iron ore.

Iron is a chemical element with the symbol Fe (Latin: ferrum) and atomic number 26. Iron is a group 8 and period 4 element on the periodic table. Iron is a lustrous, silvery soft metal. It is one of the few ferromagnetic elements.

Iron and nickel are notable for being the final elements produced by stellar nucleosynthesis, and are therefore the heaviest elements which do not require a red giant or supernova for formation. Iron and nickel are therefore the most abundant metals in metallic meteorites and in the dense-metal cores of planets such as Earth. Iron and nickel alloys are also the most common source of ferromagnetic materials in everyday use.

Iron is used by the UNSC in a wide array of functions, including use with tungsten to create rounds for the Magnetic Accelerator Cannons, used by the UNSC Navy warships as high-penetration weapons.