[Content and History] [Recent Issues] [Back Issues] [Subscriptions] [Contacts] See Also: [Diamond Crystals] [Excalibur Minerals] [Hudson Institute] [Minerals on CDROM] Mineral News was founded some twenty years ago and has developed a following of avid mineral collectors seeking timely information about new finds and other items of interest to the collector community. Articles are solicited from collector and scientific authors. 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 - Google Images 9 - Google Scholar 10 - Handbook of Mineralogy (MinSocAm) 11 - Handbook of Mineralogy (UofA) 12 - MinDAT 13 - MinMax(Deutsch) 14 - MinMax(English) 15 - Mineralienatlas (Deutsch) 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 : AA Mineral SpecimensB & L Fine Minerals Crystalarium.com Dan Weinrich Fine Minerals Dan Weinrich Auctions Dakota Matrix Desert Winds Gems and Minerals Excalibur Minerals Exceptional Minerals Fabre Minerals Heliodor John Betts Fine Minerals Mason's Minerals Mineral News Mineral of the Month Club Wrights Rock Shop Translate Gibbsite Mineral Data : Ask about Gibbsite here : Print or Cut-and-Paste your Gibbsite Specimen Label here :
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