Online Encyclopedia

Search over 40,000 articles from the original, classic Encyclopedia Britannica, 11th Edition.

RUTILE

Online Encyclopedia
Originally appearing in Volume V23, Page 942 of the 1911 Encyclopedia Britannica.
» Make a correction to this article.
» Add information or comments to this article.
Spread the word: del.icio.us del.icio.us it!

RUTILE , the most abundant of the three native forms of See also:

titanium dioxide (TiO2) ; the other forms being See also:anatase (q.v.) and See also:brookite (q.v.). Like anatase, it crystallizes in the tetragonal See also:system, but with different angles and cleavages, it being crystallographically related to cassiterite, with which it is isomorphous. The crystals resemble cassiterite in their prismatic See also:habit and terminal See also:pyramid planes (fig. I) and also in the twinning: the See also:prism planes are striated vertically. Geniculated twins, with e (ior) as twin-See also:plane, are of frequent occurrence, and the twinning is usually several times repeated, giving rise to triplets (fig. 2), sextets and octets. Twin-lamellae are often See also:present in the crystals. Acicular crystals are sometimes twinned together to See also:form reticulated skeletal plates to which the name " sagenite," from Gr. oayi7vn (a See also:net), is applied. A rarer type of twinning, on the plane (301), gives rise to See also:heart-shaped or See also:kite-shaped forms. There are distinct cleavages parallel to the faces of the prisms m (110) and a (See also:loo). The See also:colour is usually reddish-See also:brown, though yellowish in the very See also:fine needles, and See also:black in the ferruginous varieties (" nigrine " and " ilmeno See also:ruble "): the streak is See also:pale brown. The name rutile, given by A.

G. See also:

Werner in 1803, refers to the colour, being from the Latin rutilus (red). Crystals are transparent to opaque, and have a brilliant metallic-adamantine lustre. The hardness is 6a and the specific gravity 4.2, ranging, however, up to 5.2 in varieties containing Io% of ferric See also:oxide. The refractive indices and the See also:positive birefringence are high. Rutile occur's as a See also:primary constituent in eruptive rocks, but more frequently in schistose rocks. As delicate acicular crystals it is often enclosed in See also:mica and See also:quartz: in mica (q.v.) it gives rise to the phenomenon of asterism; and clear transparent quartz (See also:rock-crystal) enclosing rutile is often cut as a See also:gem under the name of " See also:Venus' See also:hair See also:stone " (Veneris crinis of See also:Pliny). Larger crystals occur in the cavities of See also:granite and crystalline See also:schists; very large twinned crystals have been found at See also:Graves See also:Mountain in See also:Lincoln See also:county, See also:Georgia, and See also:good specimens have been obtained from several places in See also:Norway and the Swiss and Ti:olese See also:Alps. As a secondary See also:mineral, rutile in the form of See also:minute needles is of wide See also:distribution in various sedimentary rocks, especially See also:clays and slates. As rounded grains it is often met with in auriferous sands and gravels. The mineral has little economic value: it has been used for imparting a yellow colour to See also:glass and See also:porcelain. and for this purpose is See also:mined at Risor and other places in Norway: (L. J.

End of Article: RUTILE

Additional information and Comments

There are no comments yet for this article.
» Add information or comments to this article.
Please link directly to this article:
Highlight the code below, right click, and select "copy." Then paste it into your website, email, or other HTML.
Site content, images, and layout Copyright © 2006 - Net Industries, worldwide.
Do not copy, download, transfer, or otherwise replicate the site content in whole or in part.

Links to articles and home page are always encouraged.

[back]
RUTHVEN 		[next]
RUTILIUS CLAUDIUS NAMATIANUS

Site © 2006 - Net Industries