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Download hereGENERAL DESCRIPTION
Anatase is one of the 3 modifications of titanium dioxide that one can find in nature; the others being the brookite and rutile. They are large differences in the atomic arrangement of the titanium and oxygen atoms in these 3 modifications of TiO2 which explain why we know 3 different minerals having the same chemical composition.
Anatase is formed in the alpine-type pegmatites, in igneous rocks and the sands that result from the degradation of the igneous rocks. The crystals are often lengthened and bipyramidal. They are gray-black, even gray-bluish in colour; they can be transparent.
Anatase is a relatively rare species with beautiful crystals. Such crystals were discovered in the Binn valley in Switzerland, in Minas-Gerais in Brazil and in Pakistan. There are many occurences in the Alps (Switzerland, Italy, Austria and France). Actually, the standard locality of anatase is French: St. Christophe, around Bourg-d'Oisans (Isère, France).
In France, one also reported anatase in many alpine ranges, such as Mount Blanc, Maurienne, Tarentaise, Mercantour as well in all Herycian granitic massifs (Vosges, Brittany, Morvan, Massif Central, Pyrénées...) and in many alluvial contextes (Loire, Champagne etc).
The type of this important species is kept at our Muséum national d’Histoire naturelle in Paris. It was first described in 1801 by R.J. Haüy (sample H 6401).
HISTORY : Name inspired from the Greek word [anatasis] meaning stretched, in relation to the elongated habit of its crystals
Species first described in 1801 by René-Just Haüy (1743-1822), French mineralogist and cristallographer
Type-locality: Saint-Christophe, Bourg d'Oisans, Isère, France
CHEMICAL FORMULA : TiO2
CRYSTAL SYSTEM : Tetragonal
COLOR : Brown, yellow, gray, black, blueish
DIAPHANIETY : Transparent to opaque
LUSTER : Adamantine to metallic
STREAK : White to pale yellow
MORPHOLOGIE : Bipyramidal crystals, more often
HARDNESS : 5,5-6,0
CHEMICAL CLASS: 3,89
DENSITY : IV - Oxides and hydroxides
GROUP : Anatase
STRUNZ CLASS BEFORE 2001 : 4/D.14-10
STRUNZ CLASS AFTER 2001 : 4.DD.05
