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TiO2 A brown, reddish, or black orthorhombic mineral; it is trimorphous with rutile and anatase, has hardness of 5.5-6 on Mohs scale, and a specific gravity of 3.87-4.08. Also known as pyromelane.



a mineral of composition TiO2. Sometimes contains admixtures of iron and niobium. Layered structure, consisting of octahedral groups of TiO6, united by common ribs. Crystallizes in a rhombic system. The crystals are usually tabular, less frequently prismatic and dipyramidal. Their color is yellowish brown to reddish brown; their luster is adamantine or metallic. The hardness of brookite on the mineralogical scale is 5.5-6; density, 3,900-4,200 kg/m3. The crystals are found in gold placers and in alpine-type veins in the Urals (USSR); abroad the mineral is found in Switzerland, France, Austria, and the USA.

References in periodicals archive ?
Rutile is the most stable phase at high temperatures, whereas anatase and brookite are largely common to nanometric scale in natural or synthetic form.
The optical absorption edge of brookite TiO2" Solid State Communications, 2006, 137, 154-157.
The anatase and brookite phases were found with the strongest peaks at 2[theta] = 25.
A remarkable number of other species have also been identified as inclusions in Zambian emeralds, including actinolite, tremolite, chlorite, dravite, apatite-(CaF), magnetite, hematite, quartz, fluorite, magnesite, siderite, dolomite, calcite, ankerite, niobium-rich rutile, pyrite, talc, zircon, barite, albite, lepidocrocite, glauconite, quartz, chrysoberyl, margarite, muscovite, biotite, brookite, tourmaline and chrysotile (Huong, 2008; Zwaan et al.
70) At temperatures below 600[degrees]C, nanophase brookite dominated.
The Brookite range (available from model and toy shops) features easy-to-assemble lightweight and affordable kites, which vary in size.
62% of the Earth's crust and occurs primarily in the minerals anatase, brookite, ilmenite, leucoxene, peovskite, futile, and sphene.
Titanium (iv) oxide exists in three different forms namely anatase, rutile and brookite.
Titanium dioxide has three common modifications, anatase, brookite, and rutile, the latter generally being the most stable one.
Titanium oxide is found in three structures of anatase, rutile and brookite.
In 1856 he acquired a fine brookite from Tremadog, Wales and sold it to the British Museum.
2]) is a naturally occurring mineral found primarily as futile, anatase, brookite, and ilmenite (1).