The Rutile mineral mainly comprises of titanium oxide. In fact, this is the most usual natural form in which titanium oxide is available.
Refractive indices at observable wavelengths for retail are among the highest of all known crystals and it demonstrates especially high dispersion plus large birefringence.
Derivation of Name
Rutile gets its name from the Latin "Rutilus", a pointer to its common color propensity.
One normally associates Rutile as a mineral that forms in high-pressure, high-temperature igneous and metamorphic rocks. Thermodynamically, it is the most stable mineral among the TiO2 polymorphs at any temperature. Therefore, the conversion into Rutile of these metastable polymorphs is irretrievable. Since its molecular volume is lowest among the three main types of polymorphs, it normally represents the prime phase in titanium-bearing in most of the rocks that form under metamorphism and high pressure, mainly Eclogites.
Rutile is frequently the additional mineral causing the asterism effect on various gemstones including Star Sapphire. A renowned form of Rutile is that of opaque golden-yellow needles of Quartz incorporated in the colorless, transparent Quartz. This exciting arrangement is termed as Rutilated Quartz, which is used as a gemstone and collectors mineral.
Distinguished occurrences are: Minas Gerias, Brazil; Arkansas, USA; Swiss Alps; and few African locations.
Rutile has many amazing and dissimilar colors and characteristics, which make it a captivating mineral. Rutile possesses many exceptional crystal forms along with some telltale styles, colors and associations. Its crystals vary from mirror-like lustrous to dark red sub-metallic to brilliant golden-yellow needles.
Because of these characteristics, it is exploited for manufacturing certain optical elements, particularly polarization optics for longer detectable and infrared wavelengths of up to about 4.5μm.
Its big thick crystals have reddish brown or black color while thin crystal or inclusions possess rusty yellow or golden yellow color.