Deep red, reddish brown, yellowish brown, brown, or black
Crystal habit
Tabular and striated, pyramidal or pseudohexagonal
Twinning
On {120}, uncertain
Cleavage
Poor on {120}, in traces on {001}
Fracture
Subconchoidal to irregular
Tenacity
Brittle
Mohs scale hardness
5+1⁄2 to 6
Luster
Submetallic
Streak
White, greyish or yellowish
Diaphaneity
Opaque to translucent
Specific gravity
4.08 to 4.18
Optical properties
Biaxial (+)
Refractive index
nα = 2.583 nβ = 2.584 nγ = 2.700
Birefringence
δ = 0.117
Pleochroism
Very weak, yellowish, reddish, orange to brown
2V angle
Calculated: 12° to 20°
Dispersion
0.131 (compare to diamond at 0.044)
Ultraviolet fluorescence
Non-fluorescent
References
[1][2][3][4]
Brookite is the orthorhombic variant of titanium dioxide (TiO2), which occurs in four known natural polymorphic forms (minerals with the same composition but different structure). The other three of these forms are akaogiite (monoclinic), anatase (tetragonal) and rutile (tetragonal). Brookite is rare compared to anatase and rutile and, like these forms, it exhibits photocatalytic activity.[5] Brookite also has a larger cell volume than either anatase or rutile, with 8 TiO2 groups per unit cell, compared with 4 for anatase and 2 for rutile.[6] Iron (Fe), tantalum (Ta) and niobium (Nb) are common impurities in brookite.[3]
Brookite was named in 1825 by French mineralogist Armand Lévy[3] for Henry James Brooke (1771–1857), an English crystallographer, mineralogist and wool trader.[1]
Arkansite is a variety of brookite from Magnet Cove, Arkansas, US. It is also found in the Murun Massif on the Olyokma-Chara Plateau of Eastern Siberia, Russia, part of the Aldan Shield.[7]
At temperatures above about 750 °C, brookite will revert to the rutile structure.[8]
^ abcBrookite. Webmineral.com. Retrieved on 2011-10-14.
^Gaines et al (1997) Dana’s New Mineralogy Eighth Edition. Wiley
^ abcBrookite. Mindat.org (2011-09-17). Retrieved on 2011-10-14.
^Brookite. Handbook of Mineralogy. (PDF) . Retrieved on 2011-10-14.
^Di Paola, A; Addamo, M.; Bellardita, M.; Cazzanelli, E.; Palmisano, L. (2007). "Preparation of photocatalytic brookite thin films". Thin Solid Films. 515 (7–8): 3527–3529. Bibcode:2007TSF...515.3527D. doi:10.1016/j.tsf.2006.10.114.
^Anatase and Brookite Archived 2012-03-17 at the Wayback Machine. Wikis.lib.ncsu.edu (2007-05-08). Retrieved on 2011-10-14.
^Arkansite on Mindat
^Brookite (Titanium Oxide). Galleries.com. Retrieved on 2011-10-14.
Brookite is the orthorhombic variant of titanium dioxide (TiO2), which occurs in four known natural polymorphic forms (minerals with the same composition...
crystal structures of rutile and anatase are tetragonal in symmetry whereas brookite is orthorhombic. The oxygen substructures are all slight distortions of...
Rarer polymorphs of TiO2 are known, including anatase, akaogiite, and brookite. Rutile has one of the highest refractive indices at visible wavelengths...
approximately 0.5–1.5%. Common titanium-containing minerals are anatase, brookite, ilmenite, perovskite, rutile, and titanite (sphene). Akaogiite is an extremely...
form". Terminology for pseudomorphs is "replacer after original", as in brookite after rutile. An infiltration pseudomorph, or substitution pseudomorph...
polymorphs (or mineral forms) of titanium dioxide are known to occur naturally: brookite, akaogiite, and rutile, with rutile being the most common and most stable...
Gemstones Notes Ref Kharan District Brookite, anatase, and quartz The image shows striated anatase crystals (in black), brookite blade and quartz crystals covering...
available in 1921. It is made out of titanium dioxide, from the minerals brookite, anatase, rutile, or ilmenite, currently the major source. Because of its...
dioxide (TiO2). It is a high-pressure polymorph of TiO2, along with anatase, brookite and another high-pressure phase called "TiO2 II". Rutile is the stable...
other rare and unusual minerals occur in the area of the shield, such as brookite, frankamenite, tausonite and yuksporite. Akitkan Arctica List of shields...
name is from Greek ψευδής, for false, and brookite because of its misleading similar appearance to brookite. Pseudobrookite forms as pneumatolytic deposition...
group minerals, quartz, zircon, certain feldspars, analcime, anatase, brookite, rutile, siderite and apatite. Xenotime is also known to be diagenetic:...
medium-sized cations; frameworks of edge-sharing octahedra: 05 Anatase, 10 Brookite 04.DE With medium-sized cations; with various polyhedra: 05 Downeyite,...
rutile TiO2 3.0 direct photocatalytic, n-type Oxide 2 Titanium dioxide, brookite TiO2 3.26 Oxide 2 Copper(I) oxide Cu2O 2.17 One of the most studied semiconductors...
have clean drinking water. Minerals of Karan District Anatase Cherry-red brookite Prehnite Kharan (princely state) Nausherwani tombs Qila Ladgasht "District...
from the area. There are many titanium minerals such as rutile, anatase, brookite, and perovskite, as well as some vanadium mineralization. Some rare-earth-bearing...
important oxide is TiO2, which exists in three important polymorphs; anatase, brookite, and rutile. All three are white diamagnetic solids, although mineral samples...
iron. The crystal structure of armalcolite is close to that of distorted brookite. It is based on deformed octahedra, with a titanium atom in the center...
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