Editing Iron oxide (section)

{{Short description|Class of chemical compounds composed of iron and oxygen}}
[[File:Almindeligt rust - jernoxid.jpg|thumb|260px|Electrochemically oxidized iron (rust)]]

An '''iron oxide''' is a [[chemical compound]] composed of [[iron]] and [[oxygen]]. Several iron [[oxide]]s are recognized.  Often they are [[nonstoichiometric|non-stoichiometric]]. [[Ferric oxyhydroxide]]s are a related class of compounds, perhaps the best known of which is [[rust]].<ref name="cor">{{cite book
 | last = Cornell.
 | first = RM.
 |author2=Schwertmann, U
 | title = The iron oxides: structure, properties, reactions, occurrences and 
 | year = 2003
 | publisher = Wiley VCH
 | isbn = 978-3-527-30274-1
}}</ref>

Iron oxides and oxyhydroxides are widespread in nature and play an important role in many geological and biological processes.  They are used as [[iron ore]]s, [[pigment]]s, [[Catalysis|catalysts]], and in [[thermite]], and occur in [[hemoglobin]]. Iron oxides are inexpensive and durable pigments in paints, coatings and colored concretes. Colors commonly available are in the "[[earth tone|earthy]]" end of the yellow/orange/red/brown/black range. When used as a food coloring, it has [[E number]] E172.