Cookeite Mineral Data
General Cookeite Information
Chemical Formula:
LiAl4(Si3Al)O10(OH)8
Composition:
Molecular Weight = 522.16 gm
Lithium 1.33 % Li 2.86 % Li2 O
Aluminum 25.84 % Al 48.82 % Al2 O3
Silicon 16.14 % Si 34.52 % SiO2
Hydrogen 1.54 % H 13.80 % H2 O
Oxygen 55.15 % O
______ ______
100.00 % 100.00 % = TOTAL OXIDE
Empirical Formula:
LiAl5 Si3 O10 (OH)8
Environment:
Alteration of lithia tourmalines and lepidolite in pegmatites.
IMA Status:
Valid Species (Pre-IMA) 1866
Locality:
Oxford Co., Maine, USA. Pala, San Diego Co., California, USA. Link to MinDat.org Location Data.
Name Origin:
Named for Josiah B. Cooke, Jr. (1827-1894), American mineralogist and chemist, Harvard University, Cambridge, Massachusetts, USA.
Cookeite Image
Images:
Cookeite
Comments: Large tan-colored cookeite epimorph after a large 12 cm quartz crystal. The outer faces of the epimorph are overgrown with milky quartz crystals up to 15 mm long.
Location: Bennett & Orchard Pit mines, Buckfield, Oxford Co., Maine, USA.
Scale: 17x17x11 cm.
© John Betts - Fine Minerals
Cookeite Crystallography
Axial Ratios:
a:b:c =0.5744:1:3.2138
Cell Dimensions:
a = 5.13, b = 8.93, c = 28.7, Z = 4; beta = 98.75° V = 1,299.47 Den(Calc)= 2.67
Crystal System:
Monoclinic - Prismatic H-M Symbol (2/m) Space Group: P 21 /a
X Ray Diffraction:
By Intensity(I/Io ): 2.315(1), 3.52(0.9), 4.7(0.9),
Physical Properties of Cookeite
Cleavage:
{001} Perfect
Color:
White, Green, Brown, Yellowish white, Pinkish white.
Density:
2.67
Diaphaneity:
Transparent to translucent
Fracture:
Flexible - Flexible fragments.
Habit:
Micaceous - Platy texture with "flexible" plates.
Habit:
Pseudo Hexagonal - Crystals show a hexagonal outline.
Hardness:
2.5 - Finger Nail
Luminescence:
Non-fluorescent.
Luster:
Vitreous (Glassy)
Streak:
white
Optical Properties of Cookeite
Gladstone-Dale:
CI meas = 0.044 (Good) - where the CI = (1-KPDmeas /KC ) CI calc = 0.044 (Good) - where the CI = (1-KPDcalc /KC )
KPDcalc = 0.2185,KPDmeas = 0.2185,KC = 0.2286 Ncalc = 1.61
Optical Data:
Biaxial (+), a=1.572-1.576, b=1.579-1.584, g=1.589-1.6, bire=0.0170-0.0240
Calculated Properties of Cookeite
Electron Density:
Bulk Density (Electron Density)=2.68 gm/cc note: Specific Gravity of Cookeite =2.67 gm/cc.
Fermion Index:
Fermion Index = 0.0087996327 Boson Index = 0.9912003673
Photoelectric:
PECookeite = 1.42 barns/electronU=PECookeite x r Electron Density= 3.79 barns/cc.
Radioactivity:
GRapi = 0 (Gamma Ray American Petroleum Institute Units) Cookeite is Not Radioactive
Cookeite Classification
Dana Class:
71.04.01.02 (71) Phyllosilicate Sheets of Six-Membered Rings
(71.04) interlayered 1:1, 2:1, and octahedra
(71.04.01) Chlorite group (Tri-Dioctahedral)
71.04.01.01 Donbassite Al2[Al2.33][Si3AlO10](OH)8 C 2/m 2/m
71.04.01.02 Cookeite LiAl4(Si3Al)O10(OH)8 P 21 /a 2/m
71.04.01.03 Sudoite Mg2(Al,Fe)3Si3AlO10(OH)8 C 2/m 2/m
71.04.01.04 Clinochlore (Mg,Fe)5Al(Si3Al)O10(OH)8 C 2/m 2/m
71.04.01.05 Nimite (Ni,Mg,Fe)5Al(Si3Al)O10(OH)8 C 2/m 2/m
71.04.01.06 Baileychlore (Zn,Al,[])3[Fe2Al][Si3AlO10](OH)8 C1,C1 Tri
71.04.01.07 Chamosite (Fe,Mg,Fe)5Al(Si3Al)O10(OH,O)8 C 2/m 2/m
71.04.01.08 Pennantite Mn5Al(Si3Al)O10(OH)8 C 2/m 2/m
71.04.01.09 Orthochamosite ! (Fe,Mg,Fe)5Al(Si3Al)O10(OH,O)8 C3m-pseudoHEX Ortho
71.04.01.10 Borocookeite ! Li(13x)Al(4-x)(BSi3)O10(OH,F)8[x=0-0.33] pseudo C 2/m 2/m
Strunz Class:
09.EC.55 09 - SILICATES (Germanates)
09.E - Phyllosilicates
09.EC -Phyllosilicates with mica sheets, composed of tetrahedral and octahedral nets
09.EC.55 Donbassite Al2[Al2.33][Si3AlO10](OH)8 C 2/m 2/m
09.EC.55 Baileychlore (Zn,Al,[])3[Fe2Al][Si3AlO10](OH)8 C1,C1 Tri
09.EC.55 Clinochlore (Mg,Fe)5Al(Si3Al)O10(OH)8 C 2/m 2/m
09.EC.55 Cookeite LiAl4(Si3Al)O10(OH)8 P 21 /a 2/m
09.EC.55 Chamosite (Fe,Mg,Fe)5Al(Si3Al)O10(OH,O)8 C 2/m 2/m
09.EC.55 Franklinfurnaceite Ca2(Fe,Al)MnMn3Zn2Si2O10(OH)8 C 2 2
09.EC.55 Nimite (Ni,Mg,Fe)5Al(Si3Al)O10(OH)8 C 2/m 2/m
09.EC.55 Gonyerite Mn3[Mn3Fe][(Si,Fe)4O10](OH,O)8 pseudo-HEX Ortho
09.EC.55 Odinite (Fe,Mg,Al,Fe,Ti,Mn)2.5(Si,Al)2O5(OH)4 Cm m
09.EC.55 Orthochamosite (Fe,Mg,Fe)5Al(Si3Al)O10(OH,O)8 C3m-pseudoHEX Ortho
09.EC.55 Pennantite Mn5Al(Si3Al)O10(OH)8 C 2/m 2/m
09.EC.55 Sudoite Mg2(Al,Fe)3Si3AlO10(OH)8 C 2/m 2/m
09.EC.55 Glagolevite ! NaMg6[Si3AlO10](OH,O)8•H2O C1 1
09.EC.55 Borocookeite ! Li(13x)Al(4-x)(BSi3)O10(OH,F)8[x=0-0.33] pseudo C 2/m 2/m
Other Cookeite Information
References:
NAME( Ford32) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(Enc. of Minerals,2nd ed.,1990)
See Also:
Links to other databases for Cookeite :
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 - Mineral and Gemstone Kingdom
12 - Mineralienatlas (Deutsch)
13 - Online Mineral Museum
14 - QUT Mineral Atlas
15 - Ruff.Info
16 - Scandinavian mineral gallery
17 - WWW-MINCRYST
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Cookeite
LiAl4(Si3Al)O10(OH)8
Dana No: 71.04.01.02 Strunz No: 09.EC.55
Locality:
Notes:
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