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Download hereGENERAL DESCRIPTION
Brookite is a titanium oxide. It is one of the 3 known modifications of titanium oxide that one finds in nature, the others being the anatase and rutile. It is a mineral which is formed in the alpine gneisses and schists and in the areas affected by contact metamorphism.
The crystals are tabular, more or less lengthened and striated, they can be sometimes pyramidal. They are brown with brown-reddish and have a metallic lustre.
The deposits of brookite are not very numerous. Most remarkable are the Dodo mine, Ural Mountains, Russia (tabular crystals of 3 cm), Vorderen Eichamspitze in Austria where crystals of 7 cm were discovered. It is very present in Switzerland and Germany.
In France: Saint-André d' Embrun in Hautes-Alpes; the quarry of La Lande in Morbihan: the talc quarry of Trimouns in Ariège or Bourg d’Oisans area in Isère, among others.
The location of conservation of the type of this species is not known. It was described for the first time in 1825 on a sample extracted in Twll Maen Grisial, Fron Olau, surroundings of Prenteg in Gwynedd (Caernarvonshire), Wales, UK.
HISTORY : Species dedicated to Henry James Brooke (1771-1857), English mineralogist and cristallographer
Species first described in 1825 by Serve-Dieu Abailard (also called Armand) Lévy (1795-1841), French mineralogist
Type-locality: Twll Maen Grisial, Wales, UK
CHEMICAL FORMULA : TiO2
CRYSTAL SYSTEM : Orthorhombic
COLOR : Yellowish brown to dark brown, black
DIAPHANIETY : Opaque to transparent
LUSTER : Metallic to adamantine
STREAK : White to white-gray
MORPHOLOGIE : Tabular crystals
HARDNESS : 5,5-6,0
CHEMICAL CLASS: 4,133
DENSITY : IV - Oxides and hydroxides
GROUP : Brookite
STRUNZ CLASS BEFORE 2001 : 4/D.15-10
STRUNZ CLASS AFTER 2001 : 4.DD.10
