Neodymium (III) oxide, also named Neodymium sesquioxide, is an oxide of a rare earth element. It presents light grayish-blue hexagonal crystals in appearance. Neodymium oxide is soluble in acid and insoluble in water. It is a highly insoluble and thermally stable neodymium. While oxide compounds are not conductive to electricity, they are extremely stable and useful for advanced electronics.