World Library  
Flag as Inappropriate
Email this Article


Article Id: WHEBN0000043085
Reproduction Date:

Title: Rutile  
Author: World Heritage Encyclopedia
Language: English
Subject: Titanium, Economy of Sierra Leone, Ruby, Anosy Region, Mining in Sierra Leone
Collection: Oxide Minerals, Rutile Group, Tetragonal Minerals, Titanium Minerals
Publisher: World Heritage Encyclopedia


Wine-red rutile crystals from Binn Valley in Switzerland (Size: 2.0 x 1.6 x 0.8 cm)
Category Oxide minerals
(repeating unit)
Strunz classification 04.DB.05
Crystal symmetry Tetragonal ditetragonal dipyramidal
H-M symbol: (4/m 2/m 2/m)
Space group: P 4/mnm
Unit cell a = 4.5937 Å, c = 2.9587 Å; Z = 2
Color Reddish brown, red, pale yellow, pale blue, violet, rarely grass-green; black if high in Nb–Ta
Crystal habit

Acicular to Prismatic crystals, elongated and

striated parallel to [001]
Crystal system Tetragonal ditetragonal dipyramidal
Twinning Comon on {011}, or {031}; as contact twins with two, six, or eight individuals, cyclic, polysynthetic
Cleavage {110} good, 100 moderate, parting on {092} and {011}
Fracture Uneven to sub-conchoidal
Mohs scale hardness 6.0 - 6.5
Luster Adamantine to submetallic
Streak Bright red to dark red
Diaphaneity Opaque, transparent in thin fragments
Specific gravity 4.23 increasing with Nb–Ta content
Optical properties Uniaxial (+)
Refractive index nω = 2.613 nε = 2.909 (589nm)
Birefringence 0.296 (589nm)
Pleochroism Weak to distinct brownish red-green-yellow
Dispersion strong
Fusibility Fusible in alkali carbonates
Solubility Insoluble in acids
Common impurities Fe, Nb, Ta
References [1][2][3][4]

Rutile is a mineral composed primarily of titanium dioxide, TiO2.

Rutile is the most common natural form of TiO2. Two rarer polymorphs of TiO2 are known:

Rutile has among 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 4.5μm.

Natural rutile may contain up to 10% iron and significant amounts of niobium and tantalum. Rutile derives its name from the Latin rutilus, red, in reference to the deep red color observed in some specimens when viewed by transmitted light.


  • Occurrence 1
  • Crystal structure 2
  • Uses and economic importance 3
  • Synthetic rutile 4
  • See also 5
  • References 6
  • External links 7


Rutile output in 2005

Rutile is a common accessory mineral in high-temperature and high-pressure metamorphic rocks and in igneous rocks.

Thermodynamically, rutile is the most stable polymorph of TiO2 at all temperatures, exhibiting lower total free energy than metastable phases of anatase or brookite.[5] Consequently, the transformation of the metastable TiO2 polymorphs to rutile is irreversible. As it has the lowest molecular volume of the three main polymorphs; it is generally the primary titanium bearing phase in most high-pressure metamorphic rocks, chiefly eclogites.

Rutile in quartz

Within the igneous environment, rutile is a common accessory mineral in plutonic igneous rocks, though it is also found occasionally in extrusive igneous rocks, particularly those that have deep mantle sources such as kimberlites and lamproites. Anatase and brookite are found in the igneous environment particularly as products of autogenic alteration during the cooling of plutonic rocks; anatase is also found in placer deposits sourced from primary rutile.

The occurrence of large specimen crystals is most common in pegmatites, skarns, and granite greisens. Rutile is found as an accessory mineral in some altered igneous rocks, and in certain gneisses and schists. In groups of acicular crystals it is frequently seen penetrating quartz as in the fléches d'amour from Graubünden, Switzerland. In 2005 the Republic of Sierra Leone in West Africa had a production capacity of 23% of the world's annual rutile supply, which rose to approximately 30% in 2008. The reserves, lasting for about 19 years, are estimated at 259,000,000 metric tons (285,000,000 short tons).[6]

Crystal structure

The unit cell of rutile. Ti atoms are gray; O atoms are red.

Rutile has a body-centred tetragonal unit cell, with unit cell parameters a=b=4.584 Å, and c=2.953 Å.[7] The titanium cations have a coordination number of 6 meaning they are surrounded by an octahedron of 6 oxygen atoms. The oxygen anions have a co-ordination number of 3 resulting in a trigonal planar co-ordination. Rutile also shows a screw axis when its octahedra are viewed sequentially.[8]

Uses and economic importance

Acicular crystals of rutile protruding from a quartz crystal

In large enough quantities in beach sands, rutile forms an important constituent of heavy minerals and ore deposits. Miners extract and separate the valuable minerals—e.g., rutile, zircon, and ilmenite. The main uses for rutile are the manufacture of refractory ceramic, as a pigment, and for the production of titanium metal.

Finely powdered rutile is a brilliant white pigment and is used in paints, plastics, paper, foods, and other applications that call for a bright white color. Titanium dioxide pigment is the single greatest use of titanium worldwide. Nanoscale particles of rutile are transparent to visible light but are highly effective in the absorption of ultraviolet radiation. The UV absorption of nano-sized rutile particles is blue-shifted compared to bulk rutile, so that higher-energy UV light is absorbed by the nanoparticles. Hence, they are used in sunscreens to protect against UV-induced skin damage.

Small rutile needles present in gems are responsible for an optical phenomenon known as asterism. Asteriated gems are known as "star" gems. Star sapphires, star rubies, and other "star" gems are highly sought after and are generally more valuable than their normal counterparts.

Rutile is widely used as a welding electrode covering. It is also used as a part of the ZTR index, which classifies highly weathered sediments.

Synthetic rutile

Synthetic rutile was first produced in 1948 and is sold under a variety of names. Very pure synthetic rutile is transparent and almost colorless (slightly yellow) in large pieces. Synthetic rutile can be made in a variety of colors by doping. The high refractive index gives an adamantine luster and strong refraction that leads to a diamond-like appearance. The near-colorless diamond substitute is sold as "Titania", which is the old-fashioned chemical name for this oxide. However, rutile is seldom used in jewellery because it is not very hard (scratch-resistant), measuring only about 6 on the Mohs hardness scale.

See also


  1. ^ Handbook of Mineralogy
  2. ^ Webmineral data
  3. ^
  4. ^ Klein, Cornelis and Cornelius S. Hurlbut, 1985, Manual of Mineralogy, 20th ed., John Wiley and Sons, New York, p. 304-305, ISBN 0-471-80580-7
  5. ^ Hanaor, D. A. H.; Assadi, M. H. N.; Li, S.; Yu, A.; Sorrell, C. C. (2012). "2"Ab initio study of phase stability in doped TiO. Computational Mechanics 50 (2): 185–194.  
  6. ^ "Sierra Rutile Mine". Titanium Resources Group. Retrieved 2009-05-06. 
  7. ^ Diebold, Ulrike (2003). "The surface science of titanium dioxide".  
  8. ^ "Rutile Structure", Steven Dutch, Natural and Applied Sciences, University of Wisconsin — Green Bay

External links

This article was sourced from Creative Commons Attribution-ShareAlike License; additional terms may apply. World Heritage Encyclopedia content is assembled from numerous content providers, Open Access Publishing, and in compliance with The Fair Access to Science and Technology Research Act (FASTR), Wikimedia Foundation, Inc., Public Library of Science, The Encyclopedia of Life, Open Book Publishers (OBP), PubMed, U.S. National Library of Medicine, National Center for Biotechnology Information, U.S. National Library of Medicine, National Institutes of Health (NIH), U.S. Department of Health & Human Services, and, which sources content from all federal, state, local, tribal, and territorial government publication portals (.gov, .mil, .edu). Funding for and content contributors is made possible from the U.S. Congress, E-Government Act of 2002.
Crowd sourced content that is contributed to World Heritage Encyclopedia is peer reviewed and edited by our editorial staff to ensure quality scholarly research articles.
By using this site, you agree to the Terms of Use and Privacy Policy. World Heritage Encyclopedia™ is a registered trademark of the World Public Library Association, a non-profit organization.

Copyright © World Library Foundation. All rights reserved. eBooks from Project Gutenberg are sponsored by the World Library Foundation,
a 501c(4) Member's Support Non-Profit Organization, and is NOT affiliated with any governmental agency or department.