Boehmite Mineral Data

Boehmite Mineral Data +

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General Boehmite Information

Chemical Formula:

AlO(OH)

Composition:

Molecular Weight = 59.99 gm

Aluminum 44.98 % Al 84.98 % Al₂O₃

Hydrogen 1.68 % H 15.02 % H₂O

Oxygen 53.34 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

AlO(OH)

Environment:

Major constituent of most bauxite ores.

IMA Status:

Valid Species (Pre-IMA) 1927

Locality:

Subtropical areas (Jamaica, Surinam, Guyana, Georgia, USA. France, Hungary, Russia, Greece, Australia, and Guinea) of high rainfall where lateritic soils can develop on Al-bearing igne Link to MinDat.org Location Data.

Name Origin:

Named after the German geologist and paleontologist, J. Bohm (1857-1938).

Synonym:

Boehmite

Boehmite Image

Images:

Boehmite

Comments: Crystalline boehmite in bauxite rock.
Location: Bauxite, Saline County, Arkansas, USA. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Boehmite Crystallography

Axial Ratios:

a:b:c =0.2345:1:0.3026

Cell Dimensions:

a = 2.868, b = 12.227, c = 3.7, Z = 4; V = 129.75 Den(Calc)= 3.07

Crystal System:

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

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

By Intensity(I/I_o): 6.11(1), 3.164(0.65), 2.346(0.53),

Physical Properties of Boehmite

Cleavage:

[010] Good

Color:

White, Light yellow, Yellowish green.

Density:

3 - 3.07, Average = 3.03

Diaphaniety:

Translucent

Fracture:

Brittle - Generally displayed by glasses and most non-metallic minerals.

Habit:

Massive - Uniformly indistinguishable crystals forming large masses.

Habit:

Pistolitic - > 3mm rounded spherical grains.

Hardness:

3 - Calcite

Luster:

Vitreous - Pearly

Streak:

white

Optical Properties of Boehmite

Gladstone-Dale:

CI meas= 0.052 (Good) - where the CI = (1-KPDmeas/KC)
CI calc= 0.063 (Fair) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2127,KPDmeas= 0.2152,KC= 0.227

Optical Data:

Biaxial (+), a=1.646, b=1.652, g=1.661, bire=0.0150, 2V(Calc)=80, 2V(Meas)=80.

Pleochroism (x):

colorless.

Pleochroism (y):

colorless.

Pleochroism (z):

colorless.

Calculated Properties of Boehmite

Electron Density:

r_electron=3.04 gm/cc
note: r_Boehmite=3.04 gm/cc.

Fermion Index

Fermion Index = 0.00025
Boson Index = 0.99975

Photoelectric:

PE_Boehmite= 1.35 barns/electron
U=PE_Boehmite x r_electron= 4.09 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Boehmite is Not Radioactive

Boehmite Classification

Dana Class:

6.1.2.1 (6)Hydroxides and Oxides Containing Hydroxyl

(6.1)where X+++O OH

(6.1.2)Dana Group

6.1.2.1 Boehmite AlO(OH) Amam 2/m 2/m 2/m

6.1.2.2 Lepidocrocite FeO(OH) Amam 2/m 2/m 2/m

6.1.2.3 Guyanaite CrO(OH) Pnnm 2/m 2/m 2/m

Strunz Class:

IV/F.06-20 IV - Oxides

IV/F - Hydroxides and oxidic hydrates, water-bearing oxides with layered structure

IV/F.06 - Diaspore - Goethite - Faitknechtite series

IV/F.06-10 Diaspore AlO(OH) Pbnm 2/m 2/m 2/m

IV/F.06-20 Boehmite AlO(OH) Amam 2/m 2/m 2/m

IV/F.06-25 Tsumgallite! GaO(OH) Pbnm 2/m 2/m 2/m

IV/F.06-30 Goethite FeO(OH) Pbnm 2/m 2/m 2/m

IV/F.06-40 Lepidocrocite FeO(OH) Amam 2/m 2/m 2/m

IV/F.06-50 Akaganeite Fe(O,OH,Cl) I2/m 2/m

IV/F.06-60 Feroxyhyte FeO(OH) Unk Hex

IV/F.06-70 Manganite MnO(OH) B21/d 2/m

IV/F.06-80 Groutite MnO(OH) Pbnm 2/m 2/m 2/m

IV/F.06-90 Feitknechtite beta-MnO(OH) Unk Hex

Other Boehmite Information

References:

NAME( Duda&Rejl90) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(Heinrich65)

See Also:

Links to other databases for Boehmite :
1 - Am. Min. Crystal Structure Database
2 - Athena
3 - EUROmin Project
4 - Google Images
5 - Google Scholar
6 - MinDAT
7 - MinMax(Deutsch)
8 - MinMax(English)
9 - Mineralienatlas (Deutsch)
10 - QUT Mineral Atlas
11 - Ruff.Info
12 - University of Colorado - Mineral Structure Data
13 - WWW-MINCRYST

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Print or Cut-and-Paste your Boehmite Specimen Label here :

Boehmite

AlO(OH)
Dana No: 6.1.2.1 Strunz No: IV/F.06-20
Locality:

Notes: