Brookite Mineral Data

Brookite Mineral Data +

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General Brookite Information

Chemical Formula:

TiO2

Composition:

Molecular Weight = 79.88 gm

Titanium 59.94 % Ti 100.00 % TiO₂

Oxygen 40.06 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

TiO₂

IMA Status:

Valid Species (Pre-IMA) 1825

Locality:

Magnet Cove near Hot Springs, Arkansas, USA. Link to MinDat.org Location Data.

Name Origin:

Named after the English mineralogist, Henry James Brucke (1771-1857), a London mineralogist and wool trader.

Synonym:

ICSD 36408

PDF 29-1360

Brookite Image

Images:

Brookite

Comments: Brookite crystal group on matrix. During the 19th century this site produced some of the best brookite ever seen.
Location: Classic Welsh locality of Prenteg, Gwynedd, Wales, UK. Scale: 4 x 4.5 cm.
© Fabre Minerals

Brookite Crystallography

Axial Ratios:

a:b:c =0.5942:1:0.5601

Cell Dimensions:

a = 5.456, b = 9.182, c = 5.143, Z = 8; V = 257.65 Den(Calc)= 4.12

Crystal System:

Orthorhombic - DipyramidalH-M Symbol (2/m 2/m 2/m) Space Group: Pcab

$Help on X Ray Diffraction:$ X Ray Diffraction:

By Intensity(I/I_o): 3.51(1), 2.9(0.9), 3.47(0.8),

Forms:

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Forms: [ 1 1 2] [ 1 1 0]

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Crystal Structure:

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Meagher E P , Lager G A , The Canadian Mineralogist , 17 (1979) p.77-85, Polyhedral thermal expansion in the TiO2 polymorphs: Refinement, of the crystal structures of rutile and brookite at high temperature, Sample at 25 degrees C

View Additional jPOWD Structure files for Brookite
[1] [2] [3] [4]

Physical Properties of Brookite

Cleavage:

[120] Indistinct

Color:

Brown, Light brown, Dark brown, Dark reddish brown, Orange.

Density:

4.1 - 4.14, Average = 4.11

Diaphaniety:

Transparent to translucent to opaque

Fracture:

Sub Conchoidal - Fractures developed in brittle materials characterized by semi-curving surfaces.

Habit:

Platy - Sheet forms (e.g. micas).

Habit:

Tabular - Form dimensions are thin in one direction.

Hardness:

5.5-6 - Knife Blade-Orthoclase

Luminescence:

None.

Luster:

Sub Metallic

Streak:

yellowish white

Optical Properties of Brookite

Gladstone-Dale:

CI meas= -0.007 (Superior) - where the CI = (1-KPDmeas/KC)
CI calc= -0.007 (Superior) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.3958,KPDmeas= 0.3958,KC= 0.393

Optical Data:

Biaxial (+), a=2.583-2.584, b=2.584-2.588, g=2.705-2.741, bire=0.1220-0.1570, 2V(Calc)=12-20, 2V(Meas)=10. Dispersion relatively strong.

Calculated Properties of Brookite

Electron Density:

r_electron=3.92 gm/cc
note: r_Brookite=4.12 gm/cc.

Fermion Index

Fermion Index = 0.07769
Boson Index = 0.92231

Photoelectric:

PE_Brookite= 10.03 barns/electron
U=PE_Brookite x r_electron= 39.34 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Brookite is Not Radioactive

Brookite Classification

Dana Class:

4.4.5.1 (4)Simple Oxides

(4.4)with a cation charge of 4+ (A++++ O2)

(4.4.5)Dana Group

4.4.5.1 Brookite TiO2 Pcab 2/m 2/m 2/m

Strunz Class:

IV/D.15-10 IV - Oxides

IV/D - Oxides with metal : oxygen = 1:2 (MO2 and related compounds)

IV/D.15 - Brookite - Kuranakhite series

IV/D.15-10 Brookite TiO2 Pcab 2/m 2/m 2/m

IV/D.15-20 Srilankite (Ti,Zr)O2 P bcn 2/m 2/m 2/m

IV/D.15-25 Carmichaelite! (Ti,Cr,Fe)[O2-x(OH)x],x~0.5 P 2₁/c 2/m

IV/D.15-30 Tellurite TeO2 P bca 2/m 2/m 2/m

IV/D.15-40 Scrutinyite PbO2 P bcn 2/m 2/m 2/m

IV/D.15-50 Kuranakhite PbMnTeO6 Unk Ortho

Other Brookite Information

References:

NAME( Lapis) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(Ford32)

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Brookite

TiO2
Dana No: 4.4.5.1 Strunz No: IV/D.15-10
Locality:

Notes: