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Bracewellite Mineral Data
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General Bracewellite Information
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 Chemical Formula: |
Cr+++O(OH) |
| Composition: |
Molecular Weight = 85.00 gm |
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Chromium 61.17 % Cr 89.40 % Cr2O3 |
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Hydrogen 1.19 % H 10.60 % H2O |
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Oxygen 37.64 % O |
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______ ______ |
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100.00 % 100.00 % = TOTAL OXIDE |
| Empirical Formula: |
CrO(OH) |
| Environment: |
Adjacent to an incrusting ullmannite in oxidized hydrothermal base-metal deposits. |
| IMA Status: |
Approved IMA 1967 |
| Locality: |
Merume River Basin, Mazaruni, Guyana Link to MinDat.org Location Data. |
| Name Origin: |
Named after Smith Bracewell, Director of the British Guiana (now Guyana) Geological Survey. |
| Name Pronunciation: |
Bracewellite + Pronunciation  |
| Synonym: |
ICSD 27517 |
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PDF 25-1497 |
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Bracewellite Crystallography
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| Axial Ratios: |
a:b:c =0.4555:1:0.3016 |
| Cell Dimensions: |
a = 4.492, b = 9.86, c = 2.974, Z = 4; V = 131.72 Den(Calc)= 4.29 |
| Crystal System: |
Orthorhombic - Dipyramidal H-M Symbol (2/m 2/m 2/m) Space Group: Pbnm |
| X Ray Diffraction: |
By Intensity(I/Io): 4.09(1), 2.65(0.8), 2.546(0.7), |
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Physical Properties of Bracewellite
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| Color: |
Dark reddish brown, Reddish brown, Black. |
| Density: |
4.45 - 4.48, Average = 4.46 |
| Diaphaneity: |
Translucent to Opaque |
| Hardness: |
5.5-6.5 - Knife Blade-Pyrite |
| Luster: |
Adamantine - Metallic |
| Streak: |
dark brown |
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Optical Properties of Bracewellite
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| Optical Data: |
NCalc= 2.27 - from Gladstone-Dale relationship (KC = 0.2953) where Ncalc=Dcalc*KC+1
NCalc= 2.32 - from Gladstone-Dale relationship (KC = 0.2953) where Ncalc=Dmeas*KC+1
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Calculated Properties of Bracewellite
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| Electron Density: |
Bulk Density (Electron Density)=4.14 gm/cc
note: Specific Gravity of Bracewellite =4.29 gm/cc.
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| Fermion Index: |
Fermion Index = 0.05
Boson Index = 0.95 |
| Photoelectric: |
PEBracewellite = 13.79 barns/electron
U=PEBracewellite x rElectron Density= 57.08 barns/cc.
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| Radioactivity: |
GRapi = 0 (Gamma Ray American Petroleum Institute Units)
Bracewellite is Not Radioactive |
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Bracewellite Classification
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| Dana Class: |
06.01.01.05 (06)Hydroxides and Oxides Containing Hydroxyl |
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(06.01)where X+++O OH |
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(06.01.01)Diaspore group (Orthorhombic, Pnma or Pnmd) |
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06.01.01.01 Diaspore AlO(OH) Pbnm 2/m 2/m 2/m |
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06.01.01.02 Goethite FeO(OH) Pbnm 2/m 2/m 2/m |
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06.01.01.03 Groutite MnO(OH) Pbnm 2/m 2/m 2/m |
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06.01.01.04 Montroseite (V,Fe,V)O(OH) Pbnm 2/m 2/m 2/m |
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06.01.01.05 Bracewellite CrO(OH) Pbnm 2/m 2/m 2/m |
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06.01.01.06 Tsumgallite! GaO(OH) Pbnm 2/m 2/m 2/m |
| Strunz Class: |
04.FD.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.FD -Hydroxides with OH, without H2O; chains of edge-sharing octahedra |
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04.FD.10 Bracewellite CrO(OH) Pbnm 2/m 2/m 2/m |
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04.FD.10 Diaspore AlO(OH) Pbnm 2/m 2/m 2/m |
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04.FD.10 Guyanaite CrO(OH) Pnnm 2/m 2/m 2/m |
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04.FD.10 Groutite MnO(OH) Pbnm 2/m 2/m 2/m |
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04.FD.10 Goethite FeO(OH) Pbnm 2/m 2/m 2/m |
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04.FD.10 Montroseite (V,Fe,V)O(OH) Pbnm 2/m 2/m 2/m |
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04.FD.10 Tsumgallite! GaO(OH) Pbnm 2/m 2/m 2/m |
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Other Bracewellite Information
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| References: |
NAME( AntBidBlaNic3) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) |
| See Also: |
Links to other databases for Bracewellite :
1 - Am. Min. Crystal Structure Database
2 - Athena
3 - EUROmin Project
4 - Ecole des Mines de Paris
5 - GeoScienceWorld
6 - Google Images
7 - Google Scholar
8 - Handbook of Mineralogy (MinSocAm)
9 - Handbook of Mineralogy (UofA)
10 - MinDAT
11 - Mineralienatlas (Deutsch)
12 - Online Mineral Museum
13 - QUT Mineral Atlas
14 - Ruff.Info
15 - WWW-MINCRYST
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Bracewellite
Cr+++O(OH)
Dana No: 06.01.01.05 Strunz No: 04.FD.10
Locality:
Notes:
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