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Download hereGENERAL DESCRIPTION
Rutile is a titanium oxide that is present in high temperature and high pressure igneous rocks. It forms also inclusions in several minerals, as in quartz where it forms the "Venus’s hairs". It is at the origin of the asterism in minerals.
The crystals are generally prismatic, lengthened and striated. The rutile is often twinned. It is found associated with hematite in a particular form (epitaxy): the rutile twins are organized around hematite to form an impressive star-like shape.
Rutile is usually brown-red but can have a golden yellow colour.
It was discovered as large-sized crystals in Brazil, in the area of Bahia. The epitaxies of rutile on hematite were found close to Rio Grande do Sul (also Brazil). The quartz deposits with rutile inclusions are rather numerous such as Anjanabonoina in Madagascar and in the Grisons in Switzerland.
In France, rutile can be found out of crystals of small size and inclusions in quartz, as in the deposits of Lansac in the Pyrénées Orientales; Kerleven in the Finistere or the Madeleine Pass in Savoie (Alps). Rutile powder is used as white anti-UV pigment. The "starred" minerals are appreciated in jewellery.
The place of conservation of the type of this species is not known.
HISTORY : Name derived from Latin "rutilus" meaning red, in reference to its color
Species first described in 1803 by Abraham Gottlob Werner (1749-1817), German geologist (Bergwerk Academy, Freiberg, Germany)
Type-locality: Cajuelo, Burgos, Spain
CHEMICAL FORMULA : Ti O2
CRYSTAL SYSTEM : Tetragonal
COLOR : Red, brown, reddish black, violett, blue
DIAPHANIETY : Opaque
LUSTER : Adamantine to sub-metallic
STREAK : Pale brown to gray
MORPHOLOGIE : Prismatic crystals, elongated and striated
HARDNESS : 6,0-6,5
CHEMICAL CLASS: 4,25
DENSITY : IV - Oxides and hydroxides
GROUP : Rutile
STRUNZ CLASS BEFORE 2001 : 4/D.02-10
STRUNZ CLASS AFTER 2001 : 4.DB.05
