Rautaaoksidia

Rautaaoksidia, also known as iron oxide, refers to a family of compounds composed of iron and oxygen. The term covers several stable oxides of iron, primarily FeO (iron(II) oxide), Fe2O3 (iron(III) oxide, including hematite), and Fe3O4 (iron(II,III) oxide, known as magnetite). It also encompasses hydrated or mixed forms such as rust, Fe2O3·nH2O, and iron oxyhydroxides like goethite (FeO(OH)).

Occurrence and natural forms include a variety of iron-oxide minerals. Hematite and magnetite are common primary minerals, while goethite and lepidocrocite are important hydrated oxides. Rust is the everyday, poorly crystalline hydrated oxide produced by the weathering of iron in the presence of water and oxygen.

Properties vary with composition. Fe3O4 (magnetite) is magnetic and often black; Fe2O3 (hematite) is typically reddish-brown and more stable in air; FeO is unstable in ordinary conditions and readily oxidizes. Iron oxides generally exhibit low solubility in water and can be formed or converted through redox reactions. They are widely used as pigments and as catalysts or precursors in chemical synthesis and metallurgy.

Applications and uses include pigments for paints (red, yellow, and brown iron oxides), ceramics, cosmetics, and coatings. Magnetic iron oxides and related ferrites are important in electronics, data storage, and catalysis. Iron oxides also serve in environmental and agricultural contexts, such as soil conditioning and remediation.

Safety considerations involve inhalation risks from fine oxide dusts, which can irritate airways. Solid oxides are typically considered low-to-moderate hazard, but handling powdered forms requires appropriate protective equipment and dust controls. See also related oxide minerals and ferrites.