Manganese(III) oxide a structure related to the spinel structure of MnO where the oxide ions are cubic close packed. This is similar to the relationship between γ-FeO and FeO. γ-MnO is ferrimagnetic with a Néel temperature of 39 K. Manganese(III) oxide Manganese(III) oxide is a chemical compound with the formula MnO. Heating MnO in air at below 800 °C produces α-MnO (higher temperatures produce MnO). γ-MnO can be produced by oxidation followed by dehydration of manganese(II) hydroxide. Many preparations of nano-crystalline MnO have been reported, for example syntheses involving oxidation of Mn salts or reduction of MnO. Manganese (III) oxide is formed
Manganese(II) carbonate to give water-soluble salts. Manganese carbonate decomposes with release of carbon dioxide, i.e. calcining, at 200 °C to give MnO: This method is sometimes employed in the production of manganese dioxide, which is used in dry-cell batteries and for ferrites. Manganese carbonate is widely used as an additive to plant fertilizers to cure manganese deficient crops. It is also used in health foods, in ceramics as a glaze colorant and flux, and in concrete stains. It is used in medicine as a hematinic. Manganese poisoning, also known as manganism, may be caused by long-term exposure to manganese dust or fumes.