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 % Li₂O

Aluminum 25.84 % Al 48.82 % Al₂O₃

Silicon 16.14 % Si 34.52 % SiO₂

Hydrogen 1.54 % H 13.80 % H₂O

Oxygen 55.15 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

LiAl₅Si₃O₁₀(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

$Help on X Ray Diffraction:$ X Ray Diffraction:

By Intensity(I/I_o): 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:

PE_Cookeite= 1.42 barns/electron
U=PE_Cookeite x rElectron 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:

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