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Brinrobertsite Mineral Data
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General Brinrobertsite Information
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 Chemical Formula: |
(Na,K,Ca)x(Al,Fe,Mg)4(Si,Al)8O20(OH)4•3.54(H2O) [x = 0.35, n = 3.54] |
| Composition: |
Molecular Weight = 957.70 gm |
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Potassium 0.29 % K 0.34 % K2O |
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Sodium 0.53 % Na 0.71 % Na2O |
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Calcium 0.25 % Ca 0.35 % CaO |
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Magnesium 0.20 % Mg 0.34 % MgO |
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Aluminum 11.18 % Al 21.13 % Al2O3 |
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Iron 0.47 % Fe 0.60 % FeO |
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Silicon 22.99 % Si 49.19 % SiO2 |
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Hydrogen 3.06 % H 27.34 % H2O |
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Oxygen 61.03 % O |
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______ ______ |
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100.00 % 100.00 % = TOTAL OXIDE |
| Empirical Formula: |
Na0.22K0.07Ca0.06Al3.81Mg0.08Fe2+0.08Si7.84Al0.16O20(OH)43.54(H2O)3.54 |
| Environment: |
Found in an Ordovician soapy mudtone (metabentonite). Altered from ash (glass) with pyrophyllite as the precursor mineral. |
| IMA Status: |
Approved IMA 2002 (Dana # Added) |
| Locality: |
Bangor, North Wales, England, Great Britain Link to MinDat.org Location Data. |
| Name Origin: |
Named for Brin Roberts, specialist for British clay minerals in the University of London. |
| Synonym: |
IMA1997-040 |
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Brinrobertsite Crystallography
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| Axial Ratios: |
a:b:c =0.5714:1:2.6813 |
| Cell Dimensions: |
a = 5.2, b = 9.1, c = 24.4, Z = 2; beta = 90° V = 1,154.61 Den(Calc)= 2.75 |
| Crystal System: |
Monoclinic - Prismatic H-M Symbol (2/m) Space Group: pseudo 2/m |
| X Ray Diffraction: |
By Intensity(I/Io): 10.99(1)(002), 22.29(0.48)(001), 3.17(0.33)(007),5.48(0.07)(004), 2.01(0.04)(0.0.11), |
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Physical Properties of Brinrobertsite
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| Cleavage: |
{001} Perfect |
| Color: |
Gray, Yellowish gray. |
| Diaphaneity: |
Transparent |
| Habit: |
Anhedral Grains - Granular minerals without the expression of crystal shapes |
| Habit: |
Earthy - Dull, clay-like texture with no visible crystalline affinities, (e.g. howlite). |
| Habit: |
Microscopic Crystals - Crystals visible only with microscopes. |
| Luster: |
Earthy (Dull) |
| Streak: |
white |
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Optical Properties of Brinrobertsite
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| Optical Data: |
Biaxial (?) |
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NCalc= 1.67 - from Gladstone-Dale relationship (KC = 0.2436) where Ncalc=Dcalc*KC+1
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Calculated Properties of Brinrobertsite
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| Electron Density: |
Bulk Density (Electron Density)=2.82 gm/cc
note: Specific Gravity of Brinrobertsite =2.75 gm/cc.
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| Fermion Index: |
Fermion Index = 0.01
Boson Index = 0.99 |
| Photoelectric: |
PEBrinrobertsite = 1.48 barns/electron
U=PEBrinrobertsite x relectron= 4.17 barns/cc.
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| Radioactivity: |
GRapi = 4.25 (Gamma Ray American Petroleum Institute Units)
Concentration of Brinrobertsite per GRapi unit = 23.56 (%)
Estimated Radioactivity from Brinrobertsite  - barely detectable
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Brinrobertsite Classification
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| Dana Class: |
71.02.01.06 (71)Phyllosilicate Sheets of Six-Membered Rings |
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(71.02)with 2:1 Layers |
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(71.02.01)Pyrophyllite-talc group |
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71.02.01.01 Pyrophyllite Al2Si4O10(OH)2 P1 1 |
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71.02.01.02 Ferripyrophyllite Fe2Si4O10(OH)2 C 2/m 2/m |
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71.02.01.03 Talc Mg3Si4O10(OH)2 C 2/c 2/m |
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71.02.01.04 Willemseite (Ni,Mg)3Si4O10(OH)2 C 2/c 2/m |
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71.02.01.05 Minnesotaite (Fe,Mg)3Si4O10(OH)2 C1 1 |
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71.02.01.06 Brinrobertsite! (Na,K,Ca)x(Al,Fe,Mg)4(Si,Al)8O20(OH)4•3.54(H2O)[x=0.35,n=3.54] pseudo 2/m 2/m |
| Strunz Class: |
09.EC.60 09 - SILICATES (Germanates) |
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09.E - Phyllosilicates |
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09.EC -Phyllosilicates with mica sheets, composed of tetrahedral and octahedral nets |
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09.EC.60 Aliettite [Mg3Si4O10(OH)2](Ca0.5,Na)0.33(Al,Mg,Fe)2-3(Si,Al)4O10(OH)2•n(H2O) Unk Mono |
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09.EC.60 Dozyite (Mg7Al2)(Si4Al2)O15(OH)12 Cm m |
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09.EC.60 Corrensite (Ca,Na,K)(Mg,Fe,Al)9(Si,Al)8O20(OH)10•n(H2O) Unk Ortho |
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09.EC.60 Kulkeite Na0.35Mg8AlSi7O20(OH)10 Unk Mono |
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09.EC.60 Karpinskite (Mg,Ni)2Si2O5(OH)2(?) Unk Mono |
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09.EC.60 Illite* (K,H3O)(Al,Mg,Fe)2(Si,Al)4O10[(OH)2,(H2O)] C 2/m 2/m |
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09.EC.60 Hydrobiotite [K(Mg,Fe)3(Al,Fe)Si3O10(OH,F)2]•[(Mg,Fe,Al)3(Si,Al)4O10(OH)2•4(H2O)] C 2/m 2/m |
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09.EC.60 Lunijianlaite LiAl6(Si7Al)O20(OH)10 Unk Mono |
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09.EC.60 Rectorite (Na,Ca)Al4(Si,Al)8O20(OH)4•2(H2O) Unk Mono |
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09.EC.60 Saliotite Na0.5Li0.5Al3AlSi3O10(OH)5 C 2/m 2/m |
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09.EC.60 Tosudite Na0,5(Al,Mg)6(Si,Al)8O18(OH)12•5(H2O) Unk Ortho |
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09.EC.60 Brinrobertsite! (Na,K,Ca)x(Al,Fe,Mg)4(Si,Al)8O20(OH)4•3.54(H2O)[x=0.35,n=3.54] pseudo 2/m 2/m |
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Other Brinrobertsite Information
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| References: |
NAME( AmMin, v 88, p 931) PHYS. PROP.(AmMin, v 88, p 931) |
| See Also: |
Links to other databases for Brinrobertsite :
1 - Am. Min. Crystal Structure Database
2 - Athena
3 - GeoScienceWorld
4 - Google Images
5 - Google Scholar
6 - MinDAT
7 - Mineralienatlas (Deutsch)
8 - Online Mineral Museum
9 - QUT Mineral Atlas
10 - Ruff.Info
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Brinrobertsite
(Na,K,Ca)x(Al,Fe,Mg)4(Si,Al)8O20(OH)4•3.54(H2O) [x = 0.35, n = 3.54]
Dana No: 71.02.01.06 Strunz No: 09.EC.60
Locality:
Notes:
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