Magnesium oxide Magnesium oxide Magnesium oxide (MgO), or magnesia, is a white hygroscopic solid mineral that occurs naturally as periclase and is a source of magnesium (see also oxide). It has an empirical formula of and consists of a lattice of Mg ions and O ions held together by ionic bonding. Magnesium hydroxide forms in the presence of water (MgO + HO → Mg(OH)), but it can be reversed by heating it to separate moisture. Magnesium oxide was historically known as magnesia alba (literally, the white mineral from magnesia – other sources give magnesia alba as MgCO), to differentiate it from "magnesia
Holmium(III) oxide Holmium(III) oxide Holmium(III) oxide, or holmium oxide is a chemical compound of a rare-earth element holmium and oxygen with the formula HoO. Together with dysprosium(III) oxide (DyO) holmium oxide is one of the most powerfully paramagnetic substances known. The oxide, also called holmia, occurs as a component of the related erbium oxide mineral called erbia. Typically the oxides of the trivalent lanthanides coexist in nature and separation of these components requires specialized methods. Holmium oxide is used in making specialty colored glasses. Glass containing holmium oxide and holmium oxide solutions have a series of sharp optical absorption peaks in the