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Eylettersite

A valid IMA mineral species
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06247580017271923031824.jpg
Eylettersite, etc.

Kobokobo pegmatite, Mwenga Territory, South Kivu, DR Congo
04539280017271923081817.jpg
Eylettersite, etc.

Kobokobo pegmatite, Mwenga Territory, South Kivu, DR Congo
02969310017271923104059.jpg
Eylettersite

Kobokobo pegmatite, Mwenga Territory, South Kivu, DR Congo
06247580017271923031824.jpg
Eylettersite, etc.

Kobokobo pegmatite, Mwenga Territory, South Kivu, DR Congo
04539280017271923081817.jpg
Eylettersite, etc.

Kobokobo pegmatite, Mwenga Territory, South Kivu, DR Congo
02969310017271923104059.jpg
Eylettersite

Kobokobo pegmatite, Mwenga Territory, South Kivu, DR Congo
06247580017271923031824.jpg
Eylettersite, etc.

Kobokobo pegmatite, Mwenga Territory, South Kivu, DR Congo
04539280017271923081817.jpg
Eylettersite, etc.

Kobokobo pegmatite, Mwenga Territory, South Kivu, DR Congo
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About EylettersiteHide

06326100017271923123037.jpg
Lea Eyletters and L. Van Wambeke
Formula:
Th0.75Al3(PO4)2(OH)6
The type material contains minor Pb replacing Th, and minor Si replacing P.
Colour:
Cream white
Lustre:
Vitreous
Hardness:
3 - 4
Specific Gravity:
3.34 - 3.38
Crystal System:
Trigonal
Name:
Named in 1972 by L. Van Wambeke after his wife, Lea Eyletters.
This page provides mineralogical data about Eylettersite.


Unique IdentifiersHide

Mindat ID:
1430
Long-form identifier:
mindat:1:1:1430:0

IMA Classification of EylettersiteHide

Classification of EylettersiteHide

Strunz-mindat (2026):
8.BL.10

8 : PHOSPHATES, ARSENATES, VANADATES
B : Phosphates, etc., with additional anions, without H2O
L : With medium-sized and large cations, (OH, etc.):RO4 = 3:1
Dana 8th ed.:
41.5.12.2

41 : ANHYDROUS PHOSPHATES, ETC.CONTAINING HYDROXYL OR HALOGEN
5 : (AB)2(XO4)Zq
Hey's CIM Ref.:
17.6.17

17 : Silicates Containing other Anions
6 : Silicates with phosphate

Mineral SymbolsHide

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

SymbolSourceReference for Standard
EylIMA–CNMNCWarr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43

Physical Properties of EylettersiteHide

Lustre:
Vitreous
Transparency:
Transparent
Colour:
Cream white
Streak:
White
Hardness:
3 - 4 on Mohs scale
Density:
3.34 - 3.38 g/cm3 (Measured)    3.47(3) g/cm3 (Calculated)

Optical Data of EylettersiteHide

Type:
Uniaxial (-)
RI values:
nε = 1.615 - 1.66
Surface Relief:
Unknown

Chemistry of EylettersiteHide

Mindat Formula:
Th0.75Al3(PO4)2(OH)6

The type material contains minor Pb replacing Th, and minor Si replacing P.
Element Weights:
Element% weight
O40.952 %
Th31.817 %
Al14.799 %
P11.326 %
H1.106 %

Calculated from ideal end-member formula.
Elements listed:
Al, H, O, P, Th - search for minerals with similar chemistry

Crystallography of EylettersiteHide

Crystal System:
Trigonal
Class (H-M):
3m(32/m) - Hexagonal Scalenohedral
Space Group:
R3m
Setting:
R3m
Cell Parameters:
a = 6.99 Å, c = 16.68(2) Å
Ratio:
a:c = 1 : 2.386
Unit Cell V:
705.80 ų (Calculated from Unit Cell)
Z:
3

X-Ray Powder DiffractionHide

Powder Diffraction Data:
d-spacingIntensity
2.95 Å(100)
3.51 Å(60)
5.70 Å(55)
2.187 Å(40)
1.899 Å(30)
1.748 Å(20)
2.848 Å(15)
Comments:
Kobokobo pegmatite, Congo. Data from the type description.

Type Occurrence of EylettersiteHide

Type Locality:
ⓘ Kobokobo pegmatite, Mwenga Territory, South Kivu, DR Congo
General Appearance of Type Material:
pulverant
Place of Conservation of Type Material:
Euratom, Ispra, Italy
National Museum of Natural History, Washington, D.C.,
USA, 136443
Geological Setting of Type Material:
alteration product of thorian crandallite in a phosphate-rich granite
Associated Minerals at Type Locality:
Autunite'Cyrtolite'Feldspar GroupFluorapatite'Limonite'
Phosphuranylite
Reference:
Van Wambeke, L. (1972) Eylettersite, un nouveau minéral de thorium appartenant à la série de la crandallite. Bulletin de Minéralogie, 95 (1). 98-105 doi:10.3406/bulmi.1972.6649

Synonyms of EylettersiteHide

Other Language Names for EylettersiteHide

Relationship of Eylettersite to other SpeciesHide

Member of:
Plumbogummite Group > Alunite Supergroup
Other Members of Plumbogummite Group:
ArsenobenauiteSrFe3+3(AsO4)(AsO3OH)(OH)6Trig. 3m(32/m) : R3m
BenauiteSrFe3+3(PO4)(PO3OH)(OH)6Trig. 3m(32/m) : R3m
CrandalliteCaAl3(PO4)(PO3OH)(OH)6Trig. 3m(32/m) : R3m
Florencite-(Ce)CeAl3(PO4)2(OH)6Trig. 3m(32/m) : R3m
Florencite-(La)LaAl3(PO4)2(OH)6Trig. 3m(32/m) : R3m
Florencite-(Nd)NdAl3(PO4)2(OH)6Trig. 3m(32/m) : R3m
Florencite-(Sm)SmAl3(PO4)2(OH)6Trig. 3m(32/m) : R3m
GalloplumbogummitePb(Ga,Al,Ge)3(PO4)2(OH)6Trig. 3m : R3m
GorceixiteBaAl3(PO4)(PO3OH)(OH)6Mon. m : Bm
GoyaziteSrAl3(PO4)(PO3OH)(OH)6Trig. 3m(32/m) : R3m
KintoreitePbFe3(PO4)(PO3OH)(OH)6Trig. 3m(32/m) : R3m
'Kintoreite-2c'PbFe3+3(PO4)2(OH,H2O)6
PlumbogummitePbAl3(PO4)(PO3OH)(OH)6Trig. 3m(32/m) : R3m
SpringcreekiteBaV3+3(PO4)2(OH,H2O)6Trig. 3m(32/m) : R3m
'UM2006-23-PO:AlBiCaFeH'(Ca,Bi)(Fe,Al)3(PO4)(PO3OH)(OH)6
'Unnamed (As-analogue of Zaïrite)'(Bi,Pb)Fe3+3(AsO4)2(OH)6
WaylanditeBiAl3(PO4)2(OH)6Trig. 3m(32/m) : R3m
ZaïriteBiFe3+3(PO4)2(OH)6Trig. 3m(32/m) : R3m

Common AssociatesHide

Associations Based on Photo Data:
2 photos of Eylettersite associated with MunditeAl(UO2)3(PO4)2(OH)3 · 5.5H2O
2 photos of Eylettersite associated with ThreadgolditeAl(UO2)2(PO4)2(OH) · 8H2O
2 photos of Eylettersite associated with PhuralumiteAl2[(UO2)3(PO4)2O(OH)](OH)3(H2O)9
1 photo of Eylettersite associated with AutuniteCa(UO2)2(PO4)2 · 10-12H2O
1 photo of Eylettersite associated with MicroclineK(AlSi3O8)
1 photo of Eylettersite associated with QuartzSiO2

Related Minerals - Strunz-mindat GroupingHide

8.BL.KiryuiteNaMnAl(PO4)F3Mon. 2/m : P21/m
8.BL.MetaheimitePbCu2(AsO4)(OH)3Mon. 2/m : P21/b
8.BL.Graulichite-(La)LaFe3+3(AsO4)2(OH)6Trig. 3m(32/m) : R3m
8.BL.ClouditeBaFe3+3(PO4)(SO4)(OH)6Trig. 3m(32/m) : R3m
8.BL.OberwolfachiteSrFe3+3(AsO4)(SO4)(OH)6Trig. 3m(32/m) : R3m
8.BL.ArsenobenauiteSrFe3+3(AsO4)(AsO3OH)(OH)6Trig. 3m(32/m) : R3m
8.BL.05GallobeudantitePbGa3(AsO4)(SO4)(OH)6Trig. 3m : R3m
8.BL.05SlottaiteSrFe3+3(PO4)(SO4)(OH)6Trig. 3m(32/m) : R3m
8.BL.05CorkitePbFe3+3(PO4)(SO4)(OH)6Trig. 3m(32/m) : R3m
8.BL.05HidalgoitePbAl3(AsO4)(SO4)(OH)6Trig. 3m : R3m
8.BL.05HinsdalitePbAl3(PO4)(SO4)(OH)6Trig. 3m(32/m) : R3m
8.BL.05'UM2011-07-POSO:AlBaH'BaAl3(PO4)(SO4)(OH)6
8.BL.05KemmlitziteSrAl3(AsO4)(SO4)(OH)6Trig. 3m(32/m) : R3m
8.BL.05BeudantitePbFe3+3(AsO4)(SO4)(OH)6Trig. 3m(32/m) : R3m
8.BL.05WeileriteBaAl3(AsO4)(SO4)(OH)6Hex.
8.BL.05WoodhouseiteCaAl3(PO4)(SO4)(OH)6Trig. 3m(32/m) : R3m
8.BL.05SvanbergiteSrAl3(PO4)(SO4)(OH)6Trig. 3m(32/m) : R3m
8.BL.10SegnititePbFe3+3AsO4(AsO3OH)(OH)6Trig. 3m(32/m) : R3m
8.BL.10ArsenogoyaziteSrAl3(AsO4)(AsO3OH)(OH)6Trig. 3m(32/m) : R3m
8.BL.10ArsenogorceixiteBaAl3(AsO4)(AsO3OH)(OH)6Trig. 3m(32/m) : R3m
8.BL.10DussertiteBaFe3+3(AsO4)(AsO3OH)(OH)6Trig. 3m(32/m) : R3m
8.BL.10GalloplumbogummitePb(Ga,Al,Ge)3(PO4)2(OH)6Trig. 3m : R3m
8.BL.10StibiosegnititePb(Fe3+2.5Sb5+0.5)(AsO4)2(OH)6Trig. 3m(32/m) : R3m
8.BL.10 va'Viséite'
8.BL.10ArsenocrandalliteCaAl3(AsO4)(AsO3OH)(OH)6Trig. 3m(32/m)
8.BL.10BenauiteSrFe3+3(PO4)(PO3OH)(OH)6Trig. 3m(32/m) : R3m
8.BL.10PhilipsbornitePbAl3(AsO4)(AsO3OH)(OH)6Trig. 3m(32/m) : R3m
8.BL.10CrandalliteCaAl3(PO4)(PO3OH)(OH)6Trig. 3m(32/m) : R3m
8.BL.10SpringcreekiteBaV3+3(PO4)2(OH,H2O)6Trig. 3m(32/m) : R3m
8.BL.10KintoreitePbFe3(PO4)(PO3OH)(OH)6Trig. 3m(32/m) : R3m
8.BL.10PlumbogummitePbAl3(PO4)(PO3OH)(OH)6Trig. 3m(32/m) : R3m
8.BL.10GorceixiteBaAl3(PO4)(PO3OH)(OH)6Mon. m : Bm
8.BL.10GoyaziteSrAl3(PO4)(PO3OH)(OH)6Trig. 3m(32/m) : R3m
8.BL.13Florencite-(Ce)CeAl3(PO4)2(OH)6Trig. 3m(32/m) : R3m
8.BL.13Florencite-(La)LaAl3(PO4)2(OH)6Trig. 3m(32/m) : R3m
8.BL.13Florencite-(Nd)NdAl3(PO4)2(OH)6Trig. 3m(32/m) : R3m
8.BL.13ZaïriteBiFe3+3(PO4)2(OH)6Trig. 3m(32/m) : R3m
8.BL.13Arsenoflorencite-(La)LaAl3(AsO4)2(OH)6Trig. 3m(32/m) : R3m
8.BL.13'Arsenoflorencite-(Nd)'NdAl3(AsO4)2(OH)6Trig.
8.BL.13'Unnamed (As-analogue of Zaïrite)'(Bi,Pb)Fe3+3(AsO4)2(OH)6
8.BL.13Arsenoflorencite-(Ce)CeAl3(AsO4)2(OH)6Trig. 3m(32/m) : R3m
8.BL.13Graulichite-(Ce)CeFe3+3(AsO4)2(OH)6Trig. 3m(32/m) : R3m
8.BL.13'Arsenowaylandite'BiAl3(AsO4)2(OH)6Trig.
8.BL.13WaylanditeBiAl3(PO4)2(OH)6Trig. 3m(32/m) : R3m
8.BL.13Florencite-(Sm)SmAl3(PO4)2(OH)6Trig. 3m(32/m) : R3m
8.BL.15ViitaniemiiteNa(Ca,Mn2+)Al(PO4)(F,OH)3Mon. 2/m : P21/m
8.BL.25PattersonitePbFe3+3(PO4)2(OH)5 · H2OTric. 1 : P1

RadioactivityHide

Radioactivity:
Element % Content Activity (Bq/kg) Radiation Type
Uranium (U) 0.0000% 0 α, β, γ
Thorium (Th) 31.8174% 1,272,696 α, β, γ
Potassium (K) 0.0000% 0 β, γ

For comparison:

  • Banana: ~15 Bq per fruit
  • Granite: 1,000–3,000 Bq/kg
  • EU exemption limit: 10,000 Bq/kg

Note: Risk is shown relative to daily recommended maximum exposure to non-background radiation of 1000 µSv/year. Note that natural background radiation averages around 2400 µSv/year so in reality these risks are probably extremely overstated! With infrequent handling and safe storage natural radioactive minerals do not usually pose much risk.

Interactive Simulator:

Note: The mass selector refers to the mass of radioactive mineral present, not the full specimen, also be aware that the matrix may also be radioactive, possibly more radioactive than this mineral!

Activity: –

DistanceDose rateRisk
1 cm
10 cm
1 m

The external dose rate (D) from a radioactive mineral is estimated by summing the gamma radiation contributions from its Uranium, Thorium, and Potassium content, disregarding daughter-product which may have a significant effect in some cases (eg 'pitchblende'). This involves multiplying the activity (A, in Bq) of each element by its specific gamma ray constant (Γ), which accounts for its unique gamma emissions. The total unshielded dose at 1 cm is then scaled by the square of the distance (r, in cm) and multiplied by a shielding factor (μshield). This calculation provides a 'worst-case' or 'maximum risk' estimate because it assumes the sample is a point source and entirely neglects any self-shielding where radiation is absorbed within the mineral itself, meaning actual doses will typically be lower. The resulting dose rate (D) is expressed in microsieverts per hour (μSv/h).

D = ((AU × ΓU) + (ATh × ΓTh) + (AK × ΓK)) / r2 × μshield

Other InformationHide

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 EylettersiteHide

References for EylettersiteHide

Localities for EylettersiteHide

Showing 3 localities.

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.
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Locality ListHide

- 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.
Brazil
 
  • Minas Gerais
    • Araxá
      • Barreiro
Neumann et al. (2015)
DR Congo (TL)
 
  • South Kivu
    • Mwenga Territory
Van Wambeke (1972) +1 other reference
Namibia
 
  • Erongo Region
    • Karibib Constituency
Schnaitmann et al. (2009)
Quick NavTopAbout EylettersiteUnique IdentifiersIMA Classification Classification Mineral SymbolsPhysical Properties Optical Data Chemistry Crystallography X-Ray Powder DiffractionType Occurrence SynonymsOther LanguagesRelationshipsCommon AssociatesStrunz-MindatRadioactivityOther InformationInternet Links References Localities Locality List
 
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