Neodymium(III) Oxide or neodymium sesquioxide is the chemical compound composed of neodymium and oxygen with the formula Nd2O3. It is soluble in acid and insoluble in water. It forms very light grayish-blue hexagonal crystals.The rare-earth mixture didymium, previously believed to be an element, partially consists of neodymium(III) oxide. Neodymium Oxide is a highly insoluble thermally stable neodymium source suitable for glass, optic and ceramic applications. Primary applications include lasers, glass coloring and tinting, and dielectrics. Neodymium Oxide is also available in pellets, pieces, sputtering targets, tablets, and nanopowder.