\▐rü-▐tēl\ n [Gr Rutil, fr. L rutilus] (1803) One of the crystalline forms of Titanium Dioxide. Used to designate a crystal structure of titanium dioxide with a sp gr of 4.2 and a refractive index of 2.69. The rutile type is characterized by higher opacity, greater density, and greater inertness as compared to the anatase type ((2002) McGraw-Hill dictionary of geology and mineralogy. McGraw-Hill, New York; Hurlbut CS, Jr. (1966) Mineralogy. Wiley, New York).