General Gibbsite InformationAl(OH)3 |
Molecular Weight = 78.00 gm |
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Aluminum 34.59 % Al 65.36 % Al2O3 |
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Hydrogen 3.88 % H 34.64 % H2O |
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Oxygen 61.53 % O |
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100.00 % 100.00 % = TOTAL OXIDE |
Al(OH)3 |
Lateritic soils developed on aluminous rocks in areas of high rainfall. |
Valid Species (Pre-IMA) 1822 |
Bauxite deposits of Arkansas, USA. Link to MinDat.org Location Data. |
Named after the American collector, G. Gibbs (1776-1833). |
Gibbsite |
Hydrargyllite |
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ICSD 36233 |
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PDF 33-18 |
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Gibbsite Crystallographya:b:c =1.7043:1:1.9169 |
a = 8.641, b = 5.07, c = 9.719, Z = 8; beta = 94.566° V = 424.44 Den(Calc)= 2.44 |
Monoclinic - PrismaticH-M Symbol (2/m) Space Group: P 21/n |
By Intensity(I/Io): 4.82(1), 4.34(0.4), 4.3(0.2), |
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| Physical Properties of Gibbsite{001} Perfect |
Bluish, Green, Green white, Gray, Gray white. |
2.3 - 2.4, Average = 2.34 |
Translucent to transparent |
Tough - Difficult to break apart as shown by fibrous minerals and most metals. |
Earthy - Dull, clay-like texture with no visible crystalline affinities, (e.g. howlite). |
Spherical - Spherical, rounded aggregates. |
Stalactitic - Shaped like pendant columns as stalactites or stalagmites (e.g. calcite). |
2.5-3 - Finger Nail-Calcite |
Non-fluorescent. |
Vitreous - Pearly |
white |
| Optical Properties of GibbsiteCI meas= 0.033 (Excellent) - where the CI = (1-KPDmeas/KC) |
CI calc= 0.069 (Fair) - where the CI = (1-KPDcalc/KC) KPDcalc= 0.2356,KPDmeas= 0.2446,KC= 0.2531 Ncalc = 1.58 - 1.62 Biaxial (+), a=1.568-1.57, b=1.568-1.57, g=1.586-1.587, bire=0.0170-0.0180, 2V(Calc)=0, 2V(Meas)=0-5. Dispersion r > v or r < v. |
colorless. |
colorless. |
| Calculated Properties of GibbsiteBulk Density (Electron Density)=2.41 gm/cc |
note: Specific Gravity of Gibbsite =2.35 gm/cc. Fermion Index = 0.0003011748 |
Boson Index = 0.9996988252 PEGibbsite = 1.10 barns/electron |
U=PEGibbsite x rElectron Density= 2.65 barns/cc. GRapi = 0 (Gamma Ray American Petroleum Institute Units) |
Gibbsite is Not Radioactive | Gibbsite Classification06.03.01.01 (06)Hydroxides and Oxides Containing Hydroxyl |
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(06.03)with (OH)3 or (OH)6 groups |
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(06.03.01)Dana Group |
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04.FE.10 04 - OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodate |
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04.F - Hydroxides (without V or U) |
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04.FE -Hydroxides with OH, without H2O; sheets of edge-sharing octahedra |
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| Other Gibbsite Information Links to other databases for Gibbsite : |
1 - Alkali-Nuts(English) 2 - Alkali-Nuts(Francais) 3 - Am. Min. Crystal Structure Database 4 - Amethyst Galleries' Mineral Gallery 5 - Athena 6 - EUROmin Project 7 - Ecole des Mines de Paris 8 - GeoScienceWorld 9 - Google Images 10 - Google Scholar 11 - Handbook of Mineralogy (MinSocAm) 12 - Handbook of Mineralogy (UofA) 13 - MinDAT 14 - Mineralienatlas (Deutsch) 15 - Online Mineral Museum 16 - QUT Mineral Atlas 17 - Ruff.Info 18 - University of Colorado - Mineral Structure Data 19 - WWW-MINCRYST Search for Gibbsite using: Visit our Advertisers for Gibbsite : B and L Fine MineralsDakota Matrix Minerals Dan & Diana Weinrich Mineral Auctions Excalibur Mineral Corp. Exceptional Minerals John Betts Fine Minerals Mineral News Mineral of the Month Club NY/NJ Gem & Mineral Show TIMA Mineral Analyzer Weinrich Minerals, Inc. Wright's Rock Shop Ask about Gibbsite here : Print or Cut-and-Paste your Gibbsite Specimen Label here :
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