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Gibbsite

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George Gibbs
Formula:
Al(OH)3
Colour:
White, light gray, light green, reddish white; reddish yellow (impure)
Lustre:
Vitreous, Sub-Vitreous, Pearly, Dull, Earthy
Hardness:
2½ - 3
Specific Gravity:
2.38 - 2.42
Crystal System:
Monoclinic
Name:
Named by John Torrey in 1822 in honor of Colonel George Gibbs [January 7, 1777, Newport, RI - August 5, 1834, Sunswick Farms, NY], of Newport, Rhode Island, USA. Gibbs was a wealthy import merchant who was a geologist and mineralogist. He helped found early scientific societies for mineralogy and geology and wrote several scientific articles on geology, mineralogy, and agriculture. He amassed the finest mineral collection in the USA up to the 1810s and the collection was eventually purchased by Yale University where it was an excellent nucleus for its research and museum collection.
Commonly as nodular white masses in laterite.


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Classification of GibbsiteHide

Approved, 'Grandfathered' (first described prior to 1959)
4.FE.10

4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
F : Hydroxides (without V or U)
E : Hydroxides with OH, without H2O; sheets of edge-sharing octahedra
6.3.1.1

6 : HYDROXIDES AND OXIDES CONTAINING HYDROXYL
3 : X(OH)3
7.6.4

7 : Oxides and Hydroxides
6 : Oxides of Al

Physical Properties of GibbsiteHide

Vitreous, Sub-Vitreous, Pearly, Dull, Earthy
Transparency:
Transparent, Translucent
Colour:
White, light gray, light green, reddish white; reddish yellow (impure)
Comment:
Ideally white; colored by mineral mixtures
Streak:
White
Hardness:
2½ - 3 on Mohs scale
Tenacity:
Brittle
Cleavage:
Perfect
{001}, but rarely observed because of its fine-grained nature.
Fracture:
Irregular/Uneven
Density:
2.38 - 2.42 g/cm3 (Measured)    2.44 g/cm3 (Calculated)

Optical Data of GibbsiteHide

Type:
Biaxial (+)
RI values:
nα = 1.568 - 1.570 nβ = 1.568 - 1.570 nγ = 1.586 - 1.587
Birefringence:
0.018
Max Birefringence:
δ = 0.018
Image shows birefringence interference colour range (at 30µm thickness)
and does not take into account mineral colouration.
Surface Relief:
Low
Dispersion:
r > v or r < v
Optical Extinction:
Y^c = 69° X = b
Pleochroism:
Non-pleochroic

Chemical Properties of GibbsiteHide

Formula:
Al(OH)3
Common Impurities:
Fe,Ga

Crystallography of GibbsiteHide

Crystal System:
Monoclinic
Class (H-M):
2/m - Prismatic
Cell Parameters:
a = 8.684 Å, b = 5.078(1) Å, c = 9.736(2) Å
β = 94.54(1)°
Ratio:
a:b:c = 1.71 : 1 : 1.917
Unit Cell V:
427.98 ų (Calculated from Unit Cell)
Z:
8
Morphology:
Almost always earthy and nodular; rare crystals tabular {001}, with {100} and (110} usually well-developed.
Twinning:
1. About [130] as twin axis, very common. 2. On {001}, common, usually in combination with other twin laws. 3. On {100}, uncommon. 4. Rare on {110}
Comment:
Space group P21/n

X-Ray Powder DiffractionHide

Powder Diffraction Data:
d-spacingIntensity
4.853 (100)
4.380 (36)
4.328 (18)
2.456 (12)
2.389 (16)
2.052 (12)
1.8074 (10)
Comments:
Also ICDD 33-18 synthetic

Type Occurrence of GibbsiteHide

Geological Setting of Type Material:
Bog iron deposit.
Associated Minerals at Type Locality:

Synonyms of GibbsiteHide

Other Language Names for GibbsiteHide

Catalan:Gibbsita
Dutch:Gibbsiet
French:Gibbsite
Italian:Gibbsite
Japanese:ギブス石
Polish:Gibbsyt
Portuguese:Gibbsita
Simplified Chinese:三水铝石
Traditional Chinese:三水鋁石
Ukrainian:Гібсит

Common AssociatesHide

Associated Minerals Based on Photo Data:
Crocoite59 photos of Gibbsite associated with Crocoite on mindat.org.
Doyleite30 photos of Gibbsite associated with Doyleite on mindat.org.
Malachite11 photos of Gibbsite associated with Malachite on mindat.org.
Cuprite10 photos of Gibbsite associated with Cuprite on mindat.org.
Azurite10 photos of Gibbsite associated with Azurite on mindat.org.
Natrolite8 photos of Gibbsite associated with Natrolite on mindat.org.
Dundasite8 photos of Gibbsite associated with Dundasite on mindat.org.
Chalcoalumite8 photos of Gibbsite associated with Chalcoalumite on mindat.org.
Alumino Adamite5 photos of Gibbsite associated with Alumino Adamite on mindat.org.
Limonite5 photos of Gibbsite associated with Limonite on mindat.org.

Related Minerals - Nickel-Strunz GroupingHide

4.FE.05Amakinite(Fe2+,Mg)(OH)2Trig.
4.FE.05BruciteMg(OH)2Trig. 3m (3 2/m) : P3m1
4.FE.05PortlanditeCa(OH)2Trig. 3m (3 2/m)
4.FE.05PyrochroiteMn(OH)2Trig. 3m (3 2/m)
4.FE.05TheophrastiteNi(OH)2Trig. 3m (3 2/m) : P3m1
4.FE.10BayeriteAl(OH)3Mon. 2/m : P21/m
4.FE.10DoyleiteAl(OH)3Tric.
4.FE.10NordstranditeAl(OH)3Tric. 1 : P1
4.FE.15BöhmiteAlO(OH)Orth. mmm (2/m 2/m 2/m)
4.FE.15Lepidocrociteγ-Fe3+O(OH)Orth. mm2 : Cmc21
4.FE.20GrimaldiiteCrO(OH)Trig.
4.FE.20HeterogeniteCo3+O(OH)Hex.
4.FE.25FeitknechtiteMn3+O(OH)Trig. 3m (3 2/m) : P3m1
4.FE.25Lithiophorite(Al,Li)MnO2(OH)2Trig. 3m (3 2/m) : R3m
4.FE.30QuenselitePbMnO2(OH)Mon. 2/m : P2/b
4.FE.35FerrihydriteFe3+10O14(OH)2Trig.
4.FE.40FeroxyhyteFe3+O(OH)Hex.
4.FE.40Vernadite(Mn4+,Fe3+,Ca,Na)(O,OH)2 · nH2OHex.
4.FE.45QuetzalcoatliteZn6Cu3(TeO6)2(OH)6 · AgxPbyClx+2yTrig. 3m (3 2/m) : P3m1

Related Minerals - Hey's Chemical Index of Minerals GroupingHide

7.6.1CorundumAl2O3Trig. 3m (3 2/m) : R3c
7.6.2BöhmiteAlO(OH)Orth. mmm (2/m 2/m 2/m)
7.6.2DiasporeAlO(OH)Orth. mmm (2/m 2/m 2/m)
7.6.5BayeriteAl(OH)3Mon. 2/m : P21/m
7.6.6NordstranditeAl(OH)3Tric. 1 : P1
7.6.7DoyleiteAl(OH)3Tric.
7.6.8Akdalaite5Al2O3 · H2OHex.

Fluorescence of GibbsiteHide

Not fluorescent.

Other InformationHide

Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.

Gibbsite in petrologyHide

Common component of (items highlighted in red)

References for GibbsiteHide

Reference List:
Sort by Year (asc) | by Year (desc) | by Author (A-Z) | by Author (Z-A)
Dewey (1820) American Journal of Science: 2: 249 (as wavellite).
Torrey (1822) New York. Med. Phys. Journal: 1, no. 1: 68.
Rose (1839) Annalen der Physik, Halle, Leipzig: 48: 564 (as hydrargillite).
Megaw (1934) Zeitschrift für Kristallographie, Mineralogie und Petrographie, Leipzig: 87: 185.
Palache, Charles, Harry Berman & Clifford Frondel (1944) The System of Mineralogy of James Dwight Dana and Edward Salisbury Dana Yale University 1837-1892, Volume I: Elements, Sulfides, Sulfosalts, Oxides. John Wiley and Sons, Inc., New York. 7th edition, revised and enlarged: 663-667.
Zeitschrift für Kristallographie, Supplement 4 (1991): 316.

Internet Links for GibbsiteHide

Localities for GibbsiteHide

This map shows a selection of localities that have latitude and longitude coordinates recorded. Click on the symbol to view information about a locality. The symbol next to localities in the list can be used to jump to that position on the map.

Locality ListShow

Mineral and/or Locality  
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