Eggletonite (original) (raw)

A valid IMA mineral species

About EggletoniteHide

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Formula:

(Na,K,Ca)2(Mn,Fe)8(Si,Al)12O29(OH)7 · 11H2O

Colour:

Dark to golden brown, red-brown

Crystal System:

Monoclinic

Name:

Named by D. Peacor, P.J. Dunn, and W.B. Simmons in 1984 in honor of Dr. Richard Anthony Eggleton, mineralogist at the Australian National University and an expert on the crystal chemistry of the stilpnomelane group of minerals. It was first found in the Big Rock Quarry by Mr. Cecil Cosse in 1975 and submitted to the Smithsonian Institution for examination in 1977.

Unique IdentifiersHide

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Long-form identifier:

mindat:1:1:1356:3

IMA Classification of EggletoniteHide

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IMA Formula:

(Na,K,Ca)xMn6(Si,Al)10O24(OH)4 · nH2O (x = 1-2; n = 7-11)

Type description reference:

Classification of EggletoniteHide

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9.EG.30

9 : SILICATES (Germanates)
E : Phyllosilicates
G : Double nets with 6-membered and larger rings

74.1.2.2

74 : PHYLLOSILICATES Modulated Layers
1 : Modulated Layers with joined islands

16.16.14

16 : Silicates Containing Aluminum and other Metals
16 : Aluminosilicates of Mn

Mineral SymbolsHide

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As of 2021 there are now IMA–CNMNC approved mineral symbols (abbreviations) for each mineral species, useful for tables and diagrams.

Please only use the official IMA–CNMNC symbol. Older variants are listed for historical use only.

Physical Properties of EggletoniteHide

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Colour:

Dark to golden brown, red-brown

Cleavage:

Perfect
[001] Perfect

Density:

2.76 g/cm3 (Measured) 2.76 g/cm3 (Calculated)

Optical Data of EggletoniteHide

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RI values:

_n_α = 1.566 _n_β = 1.606 _n_γ = 1.606

δ = 0.040

Image shows birefringence interference colour range (at 30µm thickness)
and does not take into account mineral colouration.

Comments:

X = pale brown to colorless; Y = Z = pale yellow-brown.

Chemistry of EggletoniteHide

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Mindat Formula:

(Na,K,Ca)2(Mn,Fe)8(Si,Al)12O29(OH)7 · 11H2O

Crystallography of EggletoniteHide

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Crystal System:

Monoclinic

Cell Parameters:

a = 5.55 Å, b = 13.72 Å, c = 25.00 Å
β = 93.95°

Ratio:

a:b:c = 0.405 : 1 : 1.822

Unit Cell V:

1,899.13 ų (Calculated from Unit Cell)

Comment:

Point Group: 2/m or m:; : Space Group: I2/a or Ia:

X-Ray Powder DiffractionHide

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Powder Diffraction Data:

Geological EnvironmentHide

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Type Occurrence of EggletoniteHide

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General Appearance of Type Material:

clusters of divergent sprays of radiating acicular prisms, to 2 cm

Place of Conservation of Type Material:

National Museum of Natural History, Washington, D.C., USA, 137143.

Associated Minerals at Type Locality:

Synonyms of EggletoniteHide

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Other Language Names for EggletoniteHide

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Relationship of Eggletonite to other SpeciesHide

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Other Members of Ganophyllite Group:

Common AssociatesHide

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Associated Minerals Based on Photo Data:

Related Minerals - Strunz-mindat GroupingHide

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Other InformationHide

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Health Risks:

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

Internet Links for EggletoniteHide

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References for EggletoniteHide

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Reference List:

Dunn, Pete J., Gobel, Volker, Grice, Joel D., Puziewicz, Jacek, Shigley, James E., Vanko, David A., Zilczer, Janet (1985) New mineral names. American Mineralogist, 70 (3-4) 436-441

Localities for EggletoniteHide

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This 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.

Locality ListHide

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- This locality has map coordinates listed. - This locality has estimated coordinates. ⓘ - Click for references and further information on this occurrence. ? - Indicates mineral may be doubtful at this locality. - Good crystals or important locality for species. - World class for species or very significant. (TL) - Type Locality for a valid mineral species. (FRL) - First Recorded Locality for everything else (eg varieties). Struck out - Mineral was erroneously reported from this locality. Faded * - Never found at this locality but inferred to have existed at some point in the past (e.g. from pseudomorphs).

All localities listed without proper references should be considered as questionable.