Rutile has one of the highest refractive indices at visible wavelengths of any known crystal and also exhibits a particularly large birefringence and high dispersion. Owing to these properties, it is useful for the manufacture of certain optical elements, especially polarization optics, for longer visible and infrared wavelengths up to about 4.5 micrometres. Natural rutile may contain up to 10% iron and significant amounts of niobium and tantalum.
Uses of Rutile
The primary uses of rutile and titanium oxide made from rutile are: manufacturing titanium oxide pigments, manufacturing refractory ceramics, and production of titanium metal. The use of rutile to make pigments touches the lives of almost every person in the United States in many ways almost every day.
When finely crushed and processed to remove impurities, rutile become a bright white powder that serves as an excellent pigment. It is used to make paint by suspending the powder in a liquid. The liquid serves as a carrier in the paint's application, and evaporates to deposit a layer of titanium oxide on the object that was painted. Titanium oxide pigments became very important in the paint industry in 1978, when the United States government banned the use of lead-based pigments in consumer paint products.
Titanium oxide pigments are used to produce white color in plastics, and they are used to make high-brightness paper. Titanium oxide gives these products a color that is resistant to fading. Titanium oxide is also nontoxic and chemically stable. Those properties allow it to be used as a pigment in food, cosmetics, pharmaceuticals, and many consumer products such as toothpaste.