The rutile is a Minéral composed of Dioxyde of titanium tétragonal, usually of prismatic behavior, often twinned.
The titanium dioxide also exists in the rather rare forms:
- of Anatase or octahédrite, tétragonal, of habitus octahédral;
- of Brookite, orthorhombric.
The rutile has a fracture under-conchoïdale, is friable, has a gloss metal-hard, and is commonly red brown but sometimes yellowish, bluish or purple. It is transparent or opaque. The rutile can contain up to 10% of Fer. The rutile is titanium the most stable dioxide shape and is produced at high temperature, the brookite being formed at lower temperatures and the anatase formed at temperatures even lower.
The rutile is found like an additional mineral in many kinds of magmatic rocks, like in Gneiss and Schiste S. In groups of crystals acicular he is often seen penetrating of the quartz as in the “arrows of love” coming from the Grisons, Suisse. Small rutile needles present in invaluable stones explain the presence of star in the “spangled” Saphir S, the “spangled” Rubis and other “spangled” stones, a optical Phénomène known as under the name of asterism.
The synthetic rutile was produced for the first time in 1948 and is sold under several names. It strongly refracts the light. It can be manufactured in a diversity of colors, but not in a pure transparent white, being always slightly yellow. Because of its odd appearance it is seldom used in Bijouterie. It is not very hard, about 6 on the Echelle of hardness Mohs. The substitute of the Diamant almost without color is sold under the name Titania.
The rutile derives its name from the Latin rutilus , red, in reference to its red color deep observed in some specimens by transmitted light. The natural rutile is commonly opaque or of a very dark red.
Crystallography
It is about a Minéral tétragonal, whose Groupe of space is P 4 mnm (n°136), whose Notation Strukturbericht is C4, and having for cell parameters:
- has = 4,593 3 Å;
- C = 2,959 2 Å.
See too
| Random links: | Philippe Augier | Eisbach | Frederick Manson Bailey | Professors de Poudlard | Rheinsberg |