Together titanium and oxygen form a number of stable phases, the most functional of which is titanium dioxide. As the whitest substance known, titanium dioxide is frequently utilized as a pigment in non-toxic paints and as a component in linoleum, cosmetics, high-quality paper and false teeth. For many years, titanium dioxide has also been used as a durable protective optical coating that can be layered to create various kinds of mirrors and beamsplitters.