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Glauconite

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Formula:
(K,Na)(Mg,Fe2+,Fe3+)(Fe3+,Al)(Si,Al)4O10(OH)2
Celadonite is a dioctahedral mica which may have some divalent cations in the octahedral layer.
System:
Monoclinic
Colour:
Blue-green, ...
Hardness:
2
Member of:
Name:
Named in 1828 by Christian Keferstein from the Greek "glaukos," blue-green, in allusion to its color; but the term "glauconie" was used earlier, in 1823 by Alexandre Brongniart, as a name for the English term "green sand". Both celadonite and glauconite were lumped with grünerde, the approximate German equivalent of green sand, by Dana (1844). Eventually, glauconite was applied to the sedimentary pellets, with which the species has been tied ever since, although the celadonites were essentially lumped together until the new species of the celadonite sub-group were established in 1997 by Gejing Li, Donald Ralph Peacor, Douglas S. Coombs, and Yosuke Kawachi. Rieder et.al. (1998) kept glauconite as a species in the celadonite sub-group as essentially the ferric-ferric analog of celadonite. Because of the consequent high octahedral charge contribution, the octahedral sites have vacancies and/or lower-charge cation substitutions. The range of interlayer cation site occupancy is defined as 0.6-0.85
Mica Group.

Glauconites are dioctahedral interlayer-deficient micas (as are illites).

Typically found as rounded aggregates or "pellets" of very fine grained scaly particles, having a blue-green to yellow-green color. True glauconites may have been found in other environments, but, before 1998, may have been classed as celadonite.

Classification of Glauconite

Valid - first described prior to 1959 (pre-IMA) - "Grandfathered"
Explanation of status:
The name is for a series in the Mica Group, not an individual species. While it is currently accepted, it is likely that once the species in the series have been better defined it will be replaced by two or more species names.
8/H.13-40

8 : Silicates
H : Phyllosilicates (layered), Tetragonal or pseudotetragonal layered structures [Si4O10]4- and others
13 : Mica group - Glauconite series
Dana 7th ed.:
71.2.2.5
71.2.2a.5

71 : PHYLLOSILICATES Sheets of Six-Membered Rings
2 : Sheets of 6-membered rings with 2:1 layers
16.20.10

16 : Silicates Containing Aluminum and other Metals
20 : Aluminosilicates of Fe, Mg and alkalis
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http://www.mindat.org/min-1710.html
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Occurrences of Glauconite

Geological Setting:
Formed in shallow marine environments that are mildly reducing when little or no sedimentation is taking place, hence found in shallow marine sedimentary rocks - limestones, siltstones, shales and sandstones. "Greensands" are named that because of their typically high glauconite content.

Physical Properties of Glauconite

Dull, Earthy
Diaphaneity (Transparency):
Translucent, Opaque
Colour:
Blue-green, yellow-green, green, rarely colorless.
Streak:
None
Hardness (Mohs):
2
Hardness Data:
Measured
Tenacity:
Elastic
Cleavage:
Perfect
Perfect on {001}.
Fracture:
Micaceous
Density:
2.4 - 2.95 g/cm3 (Measured)    2.9 g/cm3 (Calculated)

Crystallography of Glauconite

Crystal System:
Monoclinic
Class (H-M):
2/m - Prismatic
Space Group:
B2/m
Cell Parameters:
a = 5.234Å, b = 9.066Å, c = 10.16Å
β = 100.5°
Ratio:
a:b:c = 0.577 : 1 : 1.121
Unit Cell Volume:
V 474.03 ų (Calculated from Unit Cell)
Z:
2
Morphology:
Crystals extremely rare; typically found as rounded aggregates of very fine grained scaly particles, more rarely as tiny laths or platelets.
X-Ray Powder Diffraction Data:
d-spacingIntensity
10.1(100)
4.53(80)
3.63(400
3.33(60)
3.09(40)
2.59(100)
2.40(60)
1.511(60)
Comments:
The most common polytype is 1M. The -1M and -3T polytypes cannot be distinguished by the powder pattern.

Optical Data of Glauconite

Type:
Biaxial (-)
RI values:
nα = 1.590 - 1.612 nβ = 1.609 - 1.643 nγ = 1.610 - 1.644
2V:
Calculated: 20° to 24°
Max Birefringence:
δ = 0.020 - 0.032
Image shows birefringence interference colour range (at 30µm thickness) and does not take into account mineral colouration.
Surface Relief:
Moderate
Dispersion:
r > v

Chemical Properties of Glauconite

Formula:
(K,Na)(Mg,Fe2+,Fe3+)(Fe3+,Al)(Si,Al)4O10(OH)2

Celadonite is a dioctahedral mica which may have some divalent cations in the octahedral layer.
Idealised Formula:
(K,Na)MgFe3+(Si,Al)4O10(OH)2
Essential elements:
All elements listed in formula:
Common Impurities:
Ti,Ca,P

Relationship of Glauconite to other Species

Member of:
Other Members of Group:
AluminoceladoniteK(Mg,Fe2+)Al(Si4O10)(OH)2
Anandite(Ba,K)(Fe2+,Mg)3((Si,Al,Fe)4O10)(S,OH)2
AnniteKFe32+(AlSi3O10)(OH)2
Annite-Phlogopite Series
AspidoliteNaMg3(AlSi3O10)(OH)2
BalestraiteKLi2V5+Si4O12
Biotite
BityiteLiCaAl2(AlBeSi2O10)(OH)2
BoromuscoviteKAl2(BSi3O10)(OH)2
Brammallite(Na,H3O)(Al,Mg,Fe)2((Si,Al)4O10)(OH)2
CeladoniteK(Mg,Fe2+)Fe3+(Si4O10)(OH)2
Chernykhite(Ba,Na)(V3+,Al,Mg)2((Si,Al)4O10)(OH)2
ChromceladoniteK(Mg,Fe2+)(Cr,Al)(Si4O10)(OH)2
ChromphylliteK(Cr,Al)2(AlSi3O10)(OH,F)2
ClintoniteCa(Mg,Al)3(Al3SiO10)(OH)2
EastoniteKMg2Al(Al2Si2O10)(OH)2
EphesiteLiNaAl2(Al2Si2O10)(OH)2
FerroaluminoceladoniteK(Fe2+,Mg)(Al,Fe3+)(Si4O10)(OH)2
FerroceladoniteK(Fe2+,Mg)(Fe3+,Al)(Si4O10)(OH)2
Ferrokinoshitalite(Ba,K)(Fe2+,Mg)3(Al2Si2O10)(OH,F)2
FluoranniteKFe32+(AlSi3O10)(F,OH)2
FluorophlogopiteKMg3(AlSi3O10)(F,OH)2
Ganterite(Ba,Na,K)(Al,Mg)2(AlSi3O10)(OH)2
HendricksiteK(Zn,Mg,Mn2+)3(AlSi3O10)(OH)2
IlliteK0.65Al2.0[Al0.65Si3.35O10](OH)2
Kinoshitalite(Ba,K)(Mg,Mn2+,Al)3(Al2Si2O10)(OH)2
Lepidolite
LuanshiweiiteKLiAl1.5□0.5(Si3.5Al0.5)O10(OH,F)2
MargariteCaAl2(Al2Si2O10)(OH)2
Masutomilite(K,Rb)(Li,Mn3+,Al)3(AlSi3O10)(F,OH)2
Montdorite(K,Na)2(Fe2+,Mn2+,Mg)5(Si4O10)2(OH,F)4
MuscoviteKAl2(AlSi3O10)(OH)2
Muscovite-Celadonite Series
NanpingiteCsAl2(AlSi3O10)(OH,F)2
Natro-glauconite(Na,K)(Fe3+,Al,Mg)2((Si,Al)4O10)(OH)2
NorrishiteKLiMn23+(Si4O10)O2
Oxykinoshitalite(Ba,K)(Mg,Ti,Fe3+,Fe2+)3((Si,Al)4O10)(O,OH,F)2
OxyphlogopiteK(Mg,Ti,Fe)3[(Si,Al)4O10](O,F)2
ParagoniteNaAl2(AlSi3O10)(OH)2
Phengite
PhlogopiteKMg3(AlSi3O10)(OH)2
PolylithioniteKLi2Al(Si4O10)(F,OH)2
PreiswerkiteNaMg2Al(Al2Si2O10)(OH)2
RoscoeliteK(V3+,Al)2(AlSi3O10)(OH)2
ShirokshiniteKNaMg2(Si4O10)F2
ShirozuliteK(Mn2+,Mg)3(AlSi3O10)(OH)2
SiderophylliteKFe22+Al(Al2Si2O10)(OH)2
SokolovaiteCsLi2Al(Si4O10)F2
Suhailite(NH4)Fe32+(AlSi3O10)(OH)2
TainioliteKLiMg2(Si4O10)F2
TetraferrianniteKFe32+((Fe3+,Al)Si3O10)(OH)2
TetraferriphlogopiteKMg3(Fe3+Si3O10)(OH,F)2
Tobelite(NH4,K)Al2(AlSi3O10)(OH)2
TrilithioniteK(Li1.5Al1.5)(AlSi3O10)(F,OH)2
VoloshiniteRb(LiAl1.51.5)(Al0.5Si3.5)O10F2
Wonesite(Na,K)(Mg,Fe,Al)6((Al,Si)4O10)2(OH,F)4
YangzhumingiteKMg2.5(Si4O10)F2
ZinnwalditeKLiFe2+Al(AlSi3O10)(F,OH)2
8/H.13-10Wonesite(Na,K)(Mg,Fe,Al)6((Al,Si)4O10)2(OH,F)4
8/H.13-20Brammallite(Na,H3O)(Al,Mg,Fe)2((Si,Al)4O10)(OH)2
16.20.1Glaucophane◻[Na2][Mg3Al2]Si8O22(OH)2
16.20.2Sodium-anthophyllite
16.20.3Sodium Gedrite
16.20.4Crossite
16.20.5Ferro-eckermanniteNaNa2(Fe2+,4Al)Si8O22(OH)2
16.20.6Wonesite(Na,K)(Mg,Fe,Al)6((Al,Si)4O10)2(OH,F)4
16.20.8LennilenapeiteK6-7(Mg,Mn,Fe,Zn)48(Si,Al)72(O,OH)216 · 16H2O
16.20.9Stilpnomelane(K,Ca,Na)(Fe2+,Mg,Al,Fe3+)8(Si,Al)12(O,OH)36 · nH2O
71.2.2.1MuscoviteKAl2(AlSi3O10)(OH)2
71.2.2.2IlliteK0.65Al2.0[Al0.65Si3.35O10](OH)2
71.2.2.13AspidoliteNaMg3(AlSi3O10)(OH)2

Other Names for Glauconite

Name in Other Languages:
Basque:Glaukonita
Esperanto:Glaŭkonito
French:Glauconite
Italian:Glauconite
Lithuanian:Glaukonitas
Polish:Glaukonit
Portuguese:Glauconita
Simplified Chinese:海绿石
Slovak:Glaukonit
Spanish:Glauconita
Swedish:Glaukonit

Other Information

Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.

References for Glauconite

Reference List:
Schneider, H. (1927) A study of glauconite. Journal of Geology: 35: 289-310.

Hendricks, S.B. and Clarence S. Ross (1941), Chemical composition and genesis of glauconite and celadonite: American Mineralogist: 26: 683-708.

Bentor, Y. K. & Kestner, M. (1965): Mineralogy and origin of glauconite. Journal of Sedimentary Petrology 35, 155-166.

Foster, M. D. (1969), Studies of Celadonite and glauconite: USGS PP 614-F, 17 pp.

Slonimskaya, M. V., G. Besson, L. G. Daynyak, C. Tchoubar, and V. A. Drits (1986), The interpretation of the IR spectra of celadonites and glauconites in the region of OH-stretching frequencies: Clay Minerals: 21: 377-388.

Dainyak, L. G., and V. A. Drits (1987), Interpretation of Mössbauer spectra of nontronite, celadonite, and glauconite: Clays and Clay Minerals: 35: 363-372.

Sakharov, B. A., G. Besson, V. A. Drits, M. Y. Kameneva, A. L. Salyn, and B. B. Smoliar (1990), X-ray study of the nature of stacking faults in the structure of glauconites: Clay Minerals: 25: 419-435.

Dainyak, L. G., V. A. Drits, and L. M. Heifits (1992), Computer simulation of cation distribution in dioctahedral 2:1 layer silicates using IR-data: Application to Mössbauer spectroscopy of a glauconite sample: Clays and Clay Minerals: 40: 470-479.

Drits, V. A., L. G. Dainyak, F. Muller, G. Besson, and A. Manceau (1997a), Isomorphous cation distribution in celadonites, glauconites and Fe-illites determined by infrared, Mössbauer and EXAFS spectroscopy: Clay Minerals: 32: 153-180.

Gaines, Richard V., H. Catherine, W. Skinner, Eugene E. Foord, Brian Mason, Abraham Rosenzweig, and Vandall King (1997), Dana's New Mineralogy : The System of Mineralogy of James Dwight Dana and Edward Salisbury Dana: p. 1453.

Rieder et.al. 1998, Nomenclature of the Micas: IMA Mica Subcommittee report, Canadian Mineralogist 36: 905-912.

Internet Links for Glauconite

Localities for Glauconite

map shows a selection of localities that have latitude and longitude coordinates recorded. Click on the symbol to view information about a locality. The symbol next to localities in the list can be used to jump to that position on the map.
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