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Eggletonite

Big Photo

Big Rock Quarry (3M quarry), Granite Mountain area, Little Rock, Pulaski Co., Arkansas, USA
© Knut Eldjarn

Show Eggletonite Photos (4)
Formula:
(Na,K,Ca)
 
2
(Mn,Fe)
 
8
(Si,Al)
 
12
O
 
29
(OH)
 
7
·11H
 
2
O
System:MonoclinicColour:Brown
Lustre:VitreousHardness:3 - 4
Name:The mineral was named after Dr. Richard A. Eggleton of the Australian National University.


Ganophyllite Group. The sodium analogue of Ganophyllite.

Not to be confused with the unrelated mercury mineral Eglestonite.

Classification of Eggletonite

IMA status:Approved
Strunz 8th edition ID:8/H.17-70
Nickel-Strunz 10th (pending) edition ID:9.EG.30

9 : SILICATES (Germanates)
E : Phyllosilicates
G : Double nets with 6-membered and larger rings
Dana 7th edition ID:74.1.2.2
Dana 8th edition ID:74.1.2.2

74 : PHYLLOSILICATES Modulated Layers
1 : Modulated Layers with joined islands
Hey's CIM Ref.:16.16.14

16 : Silicates Containing Aluminum and other Metals
16 : Aluminosilicates of Mn
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Type Occurrence of Eggletonite

Type Locality:Big Rock Quarry (3M quarry), Granite Mountain area, Little Rock, Pulaski Co., Arkansas, USA
Year of Discovery:1984

Physical Properties of Eggletonite

Lustre:Vitreous
Colour:Brown
Streak:Light Brown
Hardness (Mohs):3 - 4

Crystallography of Eggletonite

Crystal System:Monoclinic
Cell Parameters:a = 5.55Å, b = 13.72Å, c = 25Å
β = 93.95°
Ratio:a:b:c = 0.405 : 1 : 1.822
Unit Cell Volume:V 1,899.13 ų (Calculated from Unit Cell)

Optical Data of Eggletonite

Type:Biaxial (-)
RI values: nα = 1.566 nβ = 1.606 nγ = 1.606
2V:Measured: 9°
Maximum Birefringence:δ = 0.040

Chart shows birefringence interference colour range (at 30µm thickness) and does not take into account mineral colouration.
Surface Relief:Moderate
Dispersion:r > v strong

Chemical Properties of Eggletonite

Formula:
(Na,K,Ca)
 
2
(Mn,Fe)
 
8
(Si,Al)
 
12
O
 
29
(OH)
 
7
·11H
 
2
O
Essential elements:H, Mn, Na, O, Si
All elements listed in formula:Al, Ca, Fe, H, K, Mn, Na, O, Si
Common Impurities:Zn,Mg

Relationship of Eggletonite to other Species

Member of Group:
Ganophyllite Group:
Related Minerals - Nickel-Strunz Grouping):

- +
9.EG.05Cymrite
BaAl
 
2
Si
 
2
(O,OH)
 
8
·H
 
2
O
9.EG.10Naujakasite
(Na,K)
 
6
(Fe
2+
 
,Mn
2+
 
,Ca)(Al,Fe)
 
4
Si
 
8
O
 
26
9.EG.10Manganonaujakasite
Na
 
6
(Mn
2+
 
,Fe
2+
 
)Al
 
4
Si
 
8
O
 
26
9.EG.15Dmisteinbergite
Ca[Al
 
2
Si
 
2
O
 
8
]
9.EG.20Kampfite
Ba
 
12
(Si
 
11
Al
 
5
)O
 
31
(CO
 
3
)
 
8
Cl
 
5
9.EG.25Strätlingite
Ca
 
2
Al
 
2
SiO
 
7
·8H
 
2
O
9.EG.25Vertumnite
Ca
 
4
Al
 
4
Si
 
4
O
 
6
(OH)
 
24
·3H
 
2
O
9.EG.30Ganophyllite
(K,Na,Ca)
 
2
Mn
 
8
(Si,Al)
 
12
(O,OH)
 
32
·8H
 
2
O
9.EG.30Tamaite
(Ca,K,Ba,Na)
 
3-4
Mn
 
24
(Si,Al)
 
40
(O,OH)
 
112
·21H
 
2
O
9.EG.35Coombsite
K(Mn,Fe,Mg)
 
13
(Si,Al)
 
18
O
 
42
(OH)
 
14
9.EG.35Zussmanite
K(Fe,Mg,Mn)
 
13
(Si,Al)
 
18
O
 
42
(OH)
 
14
9.EG.40Franklinphilite
(K,Na)
 
4
(Mn,Zn,Mg,Fe)
 
48
(Si,Al)
 
72
(O,OH)
 
216
·6H
 
2
O
9.EG.40Lennilenapeite
K
 
6-7
(Mg,Mn,Fe,Zn)
 
48
(Si,Al)
 
72
(O,OH)
 
216
·16H
 
2
O
9.EG.40Parsettensite
K
 
1.2
Mn
 
8
(Si,Al)
 
12
O
 
26
(OH)
 
10
9.EG.40Stilpnomelane
(K,Ca,Na)(Fe
2+
 
,Mg,Al,Fe
3+
 
)
 
8
(Si,Al)
 
12
(O,OH)
 
36
 · nH
 
2
O
9.EG.45Latiumite
K
 
2
Ca
 
6
(Si,Al)
 
11
O
 
25
(SO
 
4
,CO
 
3
)
9.EG.45Tuscanite
(K(Ca,Na)
 
6
(Si,Al)
 
10
O
 
22
[SO
 
4
,CO
 
3
,(OH)
 
2
]·H
 
2
O
9.EG.50Jagoite
(Pb,Ca)
 
3
FeSi
 
3
O
 
10
(Cl,OH)
9.EG.55Wickenburgite
CaPb
 
3
Al
 
2
Si
 
10
O
 
24
(OH)
 
6
9.EG.60Hyttsjöite
Pb
 
18
Ba
 
2
Ca
 
5
Mn
2+
2
Fe
3+
2
Si
 
30
O
 
90
Cl·6H
 
2
O
9.EG.65Armbrusterite
K
 
5
Na
 
7
Mn
 
15
[(OH)
 
10
|(Si
 
9
O
 
22
)
 
4
] · 4H
 
2
O
9.EG.70Britvinite
[Pb
 
7
(OH)
 
3
F(BO
 
3
)
 
2
(CO
 
3
)][Mg
 
4.5
(OH)
 
3
(Si
 
5
O
 
14
)]
9.EG.75Bannisterite
Ca
 
0.5
(K,Na)
 
0.5
(Mn,Fe,Zn)
 
10
(Si,Al)
 
16
O
 
38
(OH)
 
8
·5.5H
 
2
O
Related Minerals - Hey's Index Grouping:

- +
16.16.1Kanonaite
Mn
3+
 
Al[O|SiO
 
4
]
16.16.2Spessartine
Mn
2+
3
Al
 
2
[SiO
 
4
]
 
3
16.16.3Davreuxite
MnAl
 
6
Si
 
4
O
 
17
(OH)
 
2
16.16.4Sursassite
Mn
 
2
Al
 
3
[(OH)
 
3
|SiO
 
4
|Si
 
2
O
 
7
]
16.16.5Carpholite
Mn
2+
 
Al
 
2
[(OH)
 
4
|Si
 
2
O
 
6
]
16.16.6Kellyite
Mn
2+
2
Al[(OH)
 
4
|AlSiO
 
5
]
16.16.7Pennantite
(Mn
 
5
Al)(Si
 
3
Al)O
 
10
(OH)
 
8
16.16.8Akatoreite
(Mn
2+
 
,Fe
2+
 
)
 
9
Al
 
2
[(OH)
 
3
|HSi
 
4
O
 
13
]
 
2
16.16.9Ganophyllite
(K,Na,Ca)
 
2
Mn
 
8
(Si,Al)
 
12
(O,OH)
 
32
·8H
 
2
O
16.16.10Kôzulite
[Na][Na
 
2
][Mn
2+
4
(Fe
3+
 
,Al)][(OH)
 
2
|Si
 
8
O
 
22
]
16.16.11Masutomilite
(K,Rb)(Li,Mn
3+
 
,Al)
 
3
[(F,OH)
 
2
|AlSi
 
3
O
 
10
]
16.16.13Howieite
Na(Fe,Mn)
 
10
(Fe,Al)
 
2
Si
 
12
O
 
31
(OH)
 
13
16.16.15Bannisterite
Ca
 
0.5
(K,Na)
 
0.5
(Mn,Fe,Zn)
 
10
(Si,Al)
 
16
O
 
38
(OH)
 
8
·5.5H
 
2
O
16.16.16Taneyamalite
(Na,Ca)(Mn,Mg,Fe)
 
12
Si
 
12
(O,OH)
 
44
16.16.17Zussmanite
K(Fe,Mg,Mn)
 
13
(Si,Al)
 
18
O
 
42
(OH)
 
14
16.16.18Coombsite
K(Mn,Fe,Mg)
 
13
(Si,Al)
 
18
O
 
42
(OH)
 
14
16.16.19Henritermierite
Ca
 
3
(Mn
3+
 
,Al)
 
2
[(OH)
 
4
|(SiO
 
4
)
 
2
]
16.16.20Macfallite
Ca
 
2
(Mn
3+
 
,Al)
 
3
[(OH)
 
3
|SiO
 
4
|Si
 
2
O
 
7
]
16.16.21Ottrélite
(Mn
2+
 
,Fe
2+
 
,Mg)Al
 
2
[O|(OH)
 
2
|SiO
 
4
]
16.16.22Piemontite
{Ca
 
2
}{Al
 
2
Mn
3+
 
}[O|OH|SiO
 
4
|Si
 
2
O
 
7
]
16.16.23Okhotskite
Ca
 
8
(Mn
2+
 
,Mg)
 
4
(Mn
3+
 
,Al,Fe)
 
8
Si
 
12
O
 
56-n
(OH)
 
n
16.16.24Pumpellyite-(Mn2+)
Ca
 
2
(Mn
2+
 
,Mg)(Al,Mn
3+
 
,Fe
3+
 
)
 
2
[(OH)
 
2
|SiO
 
4
|Si
 
2
O
 
7
] · H
 
2
O
16.16.25Piemontite-(Sr)
{CaSr}{Al
 
2
Mn
3+
 
}[O|OH|SiO
 
4
|Si
 
2
O
 
7
]

Other Names for Eggletonite

Synonyms:
IMA1982-059
Other Languages:
German:Eggletonit
Spanish:Eggletonita

Other Information

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

References for Eggletonite

Reference List:Peacor, D. R.; Dunn, P. J. and Simmons, W. B. (1984): Eggletonite, the sodium analog of ganophyllite.: Mineralogical Magazine: 48, 93-96.

American Mineralogist: 70: 436.

Internet Links for Eggletonite

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  • Raman and XRD data at RRUFF project
  • American Mineralogist Crystal Structure Database
  • Search for Eggletonite in the Natural History Museum (London) online catalogue
  • Eggletonite details from Handbook of Mineralogy (PDF)
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    Localities for Eggletonite

    Hide Locality List
    The 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.
    (TL) indicates type locality. ? indicates mineral may be doubtful at this locality. All other localities listed without reference should be considered as uncertain and unproven until references can be found.
    Japan
     
    • Honshu Island
      • Kanto Region
        • Tokyo Prefecture
          • Nishi-Tama-gun
            • Okutama
    		[MinRec 32:419]
    USA
     
    • Arkansas
      • Pulaski Co.
        • Little Rock
          • Granite Mountain area
    		Mineralogical Magazine 1984 48 : 93-96.
    Mineral and/or Locality
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