Eggletonite Mineral Data

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General Eggletonite Information

Chemical Formula:

Na2Mn8[Si11AlO29](OH)7•11(H2O)

Composition:

Molecular Weight = 1,602.61 gm

Sodium 2.87 % Na 3.87 % Na₂O

Manganese 27.42 % Mn 35.41 % MnO

Aluminum 1.68 % Al 3.18 % Al₂O₃

Silicon 19.28 % Si 41.24 % SiO₂

Hydrogen 1.82 % H 16.30 % H₂O

Oxygen 46.92 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

Na₂Mn²⁺₈Si₁₁AlO₂₉(OH)₇•11(H₂O)

Environment:

Miarolitic cavities in nepheline syenite. Probably isostructural with ganophyllite.

IMA Status:

Approved IMA 1984

Locality:

Big Rock Quarry, Little Rock, Pulaski County, Arkansas, USA. Link to MinDat.org Location Data.

Name Origin:

Named for R. A. Eggleton, Australian National University.

Name Pronunciation:

Eggletonite + Pronunciation

Eggletonite Image

Images:

Eggletonite

Comments: Brown micro crystals of eggletonite in syenite.
Location: 3M Quarry, Little Rock, Pulaski County, Arkansas, USA. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Eggletonite Crystallography

Axial Ratios:

a:b:c =0.4048:1:1.8221

Cell Dimensions:

a = 5.554, b = 13.72, c = 25, Z = 2; beta = 93.95° V = 1,900.50 Den(Calc)= 2.80

Crystal System:

MonoclinicSpace Group: Ia or I2/a

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

By Intensity(I/I_o): 2.694(1), 12(1), 2.598(0.55),

Physical Properties of Eggletonite

Cleavage:

{001} Perfect

Color:

Golden brown.

Density:

2.76

Fracture:

Brittle - Generally displayed by glasses and most non-metallic minerals.

Habit:

Acicular - Occurs as needle-like crystals.

Habit:

Prismatic - Crystals Shaped like Slender Prisms (e.g. tourmaline).

Habit:

Radial - Crystals radiate from a center without producing stellar forms (e.g. stibnite)

Hardness:

3-4 - Calcite-Fluorite

Luster:

Vitreous (Glassy)

Streak:

light brown

Optical Properties of Eggletonite

Gladstone-Dale:

CI meas= 0.045 (Good) - where the CI = (1-KPDmeas/KC)
CI calc= 0.059 (Good) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2117,KPDmeas= 0.2147,KC= 0.2249
Ncalc = 1.62 - 1.63

Optical Data:

Biaxial (-), a=1.566, b=1.606, g=1.606, bire=0.0400, 2V(Calc)=0, 2V(Meas)=9.

Calculated Properties of Eggletonite

Electron Density:

Bulk Density (Electron Density)=2.73 gm/cc
note: Specific Gravity of Eggletonite =2.76 gm/cc.

Fermion Index:

Fermion Index = 0.0092304868
Boson Index = 0.9907695132

Photoelectric:

PE_Eggletonite= 7.73 barns/electron
U=PE_Eggletonite x rElectron Density= 21.13 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)
Eggletonite is Not Radioactive

Eggletonite Classification

Dana Class:

74.01.02.02 (74)Phyllosilicate Modulated Layers

(74.01)with joined islands

(74.01.02)Ganophyllite group

74.01.02.01 Ganophyllite (K,Na)2(Mn,Al,Mg)8(Si,Al)12O29(OH)7•8-9(H2O) A2/a 2/m

74.01.02.02 Eggletonite Na2Mn8[Si11AlO29](OH)7•11(H2O) Ia or I2/a Mono

74.01.02.03 Tamaite! (Ca,K,Ba,Na)3-4Mn24(Si,Al)40(O,OH)112•21(H2O) P 2₁/a 2/m

Strunz Class:

09.EG.30 09 - SILICATES (Germanates)

09.E - Phyllosilicates

09.EG -Double nets with 6-membered and larger rings

09.EG.30 Eggletonite Na2Mn8[Si11AlO29](OH)7•11(H2O) Ia or I2/a Mono

09.EG.30 Ganophyllite (K,Na)2(Mn,Al,Mg)8(Si,Al)12O29(OH)7•8-9(H2O) A2/a 2/m

09.EG.30 Tamaite! (Ca,K,Ba,Na)3-4Mn24(Si,Al)40(O,OH)112•21(H2O) P 2₁/a 2/m

Other Eggletonite Information

References:

NAME( Dana8) PHYS. PROP.(Dana8) OPTIC PROP.(Dana8)

See Also:

Links to other databases for Eggletonite :
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 - Mineralienatlas (Deutsch)
12 - Online Mineral Museum
13 - QUT Mineral Atlas
14 - Ruff.Info

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Ask about Eggletonite here :
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Mindat.org's Discussion Groups
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Rockhounds Discussion Group on Yahoo Groups
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Print or Cut-and-Paste your Eggletonite Specimen Label here :

Eggletonite

Na2Mn8[Si11AlO29](OH)7•11(H2O)
Dana No: 74.01.02.02 Strunz No: 09.EG.30
Locality:

Notes: