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Wilkinsonite

A valid IMA mineral species
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About WilkinsoniteHide

Formula:
Na2Fe2+4Fe3+2(Si6O18)O2
Colour:
Black
Lustre:
Vitreous
Hardness:
5
Specific Gravity:
3.89 (Calculated)
Crystal System:
Triclinic
Name:
Named in 1990 by M.B. Duggan in honor of John Frederick George Wilkinson (10 October 1927, Bundaberg, Queensland, Australia - 8 October 2014, Sydney, New South Wales, Australia), professor of geology, University of New England, Australia. He was a specialist in the petrology of igneous rocks.
Aenigmatite Group. The supposed Mg analogue is known as UM1991-29-SiO:FeMgNa.


Unique IdentifiersHide

Mindat ID:
4290
Long-form identifier:
mindat:1:1:4290:7

IMA Classification of WilkinsoniteHide

Classification of WilkinsoniteHide

9.DH.40

9 : SILICATES (Germanates)
D : Inosilicates
H : Inosilicates with 4-periodic single chains, Si4O12
69.2.1a.8

69 : INOSILICATES Chains with Side Branches or Loops
2 : Chains with Side Branches or Loops with P>2
14.20.4

14 : Silicates not Containing Aluminum
20 : Silicates of Fe and alkali metals

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

Physical Properties of WilkinsoniteHide

Vitreous
Transparency:
Translucent, Opaque
Colour:
Black
Streak:
Brown
Hardness:
Tenacity:
Brittle
Fracture:
Conchoidal
Density:
3.89 g/cm3 (Calculated)

Optical Data of WilkinsoniteHide

Type:
Biaxial (+)
RI values:
nα = 1.79 nβ = 1.79 nγ = 1.90
Max. Birefringence:
δ = 0.110
Based on recorded range of RI values above.

Interference Colours:
The colours simulate birefringence patterns seen in thin section under crossed polars. They do not take into account mineral colouration or opacity.

Michel-Levy Bar The default colours simulate the birefringence range for a 30 µm thin-section thickness. Adjust the slider to simulate a different thickness.

Grain Simulation You can rotate the grain simulation to show how this range might look as you rotated a sample under crossed polars. Each grain retains its interference colour (retardation) while its brightness falls to black at extinction and reaches a maximum between extinction positions.

Surface Relief:
Very High (positive)
Relative to Canada balsam mounting medium (n ≈ 1.537).

This shows the grain boundary and Becke line effect under plane-polarised light, based on the contrast between this mineral's average refractive index and the mounting medium. It does not take into account mineral colouration.
In focus
Interference Figure:
This shows the idealized biaxial acute bisectrix (Bxa) interference figure - the conoscopic view for a grain cut perpendicular to the acute bisectrix, using this mineral's 2V. The two small white dots mark the melatopes - the points where the two optic axes emerge - and are shown only when they fall within the field of view. The coloured bands are isochromatics, and the dark bands are isogyres.

Rotate the stage: at 0°/90° the isogyres form a cross through the melatopes; at 45° they pull apart into curved hyperbolas. That splitting on rotation - absent in a uniaxial figure - is the standard diagnostic test for telling biaxial minerals from uniaxial ones. If 2V is large, the melatopes may fall outside the field of view, as they often do at the microscope too.

No measured or calculated 2V is on file for this mineral, so the value used here (0°) is estimated from its recorded refractive indices and optic sign, not from a direct 2V measurement.
Dispersion:
single
Pleochroism:
Strong
Comments:
X = olive-green;
Y = gray-brown;
Z = very dark brown.

Chemistry of WilkinsoniteHide

Mindat Formula:
Na2Fe2+4Fe3+2(Si6O18)O2
Element Weights:
Element% weight
Fe38.534 %
O36.799 %
Si19.379 %
Na5.288 %

Calculated from ideal end-member formula.
Fe
O
Si
Na
Common Impurities:
Ti,Zr,Al,Cr,Nb,Mn,Ni,Mg,Ca,K

Crystallography of WilkinsoniteHide

Crystal System:
Triclinic
Class (H-M):
1 - Pinacoidal
Space Group:
P1
Cell Parameters:
a = 10.3355(5) Å, b = 10.784(4) Å, c = 8.9142(4) Å
α = 105.048(3)°, β = 96.461(3)°, γ = 125.302(2)°
Ratio:
a:b:c = 0.958 : 1 : 0.827
Unit Cell V:
738.37 ų
Z:
2

Crystal StructureHide

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IDSpeciesReferenceLinkYearLocalityPressure (GPa)Temp (K)
0010476WilkinsoniteBurt J B, Downs R T, Costin G (2007) Single-crystal X-ray refinement of wilkinsonite, Na2Fe2+4Fe3+2Si6O20. Acta Crystallographica E63 i122-i1242007Warrumbungle Volcano, central New South Wales, Australia0293
CIF Raw Data - click here to close

X-Ray Powder DiffractionHide

Powder Diffraction Data:
d-spacingIntensity
8.10 Å(100)
3.149 Å(100)
2.696 Å(80)
2.533 Å(80)
2.115 Å(70)
2.935 Å(60)
1.481 Å(50)

Geological EnvironmentHide

Paragenetic Mode(s):
Paragenetic ModeEarliest Age (Ga)
Stage 2: Planetesimal differentiation and alteration4.566-4.550
6 : Secondary asteroid phases4.566-4.560
Stage 3a: Earth’s earliest Hadean crust>4.50
9 : Lava/xenolith minerals (hornfels, sanidinite facies)
Stage 4b: Highly evolved igneous rocks>3.0
35 : Ultra-alkali and agpaitic igneous rocks

Type Occurrence of WilkinsoniteHide

Synonyms of WilkinsoniteHide

Other Language Names for WilkinsoniteHide

Relationship of Wilkinsonite to other SpeciesHide

Other Members of Aenigmatite Group:
AenigmatiteNa4[Fe2+10Ti2]O4[Si12O36]Tric. 1 : P1
KrinoviteNa2Mg4Cr3+2(Si6O18)O2Tric. 1 : P1
'UM1991-29-SiO:FeMgNa'Na4(Mg5Fe3+7)O4[Si9Fe3+3O36]

Common AssociatesHide

Associations Based on Photo Data:
1 photo of Wilkinsonite associated with AegirineNaFe3+Si2O6
1 photo of Wilkinsonite associated with 'Anorthoclase'(Na,K)AlSi3O8
1 photo of Wilkinsonite associated with SodaliteNa4(Si3Al3)O12Cl
1 photo of Wilkinsonite associated with AenigmatiteNa4[Fe2+10Ti2]O4[Si12O36]
1 photo of Wilkinsonite associated with ArfvedsoniteNaNa2(Fe2+4Fe3+)Si8O22(OH)2

Related Minerals - Strunz-mindat GroupingHide

9.DH.DevilliersiteCa4Ca2Fe3+10O4[(Fe3+10Si2)O36]Tric. 1 : P1
9.DH.'Gageite-2M'(Mn,Mg,Zn)42Si16O54(OH)40Mon. 2/m
9.DH.BavsiiteBa2V2O2[Si4O12]Tet. 4/m : I4/m
9.DH.YuzuxiangiteSr3Fe3+(Si2O6)2(OH) · 3H2OMon. 2/m : P21/m
9.DH.LouisfuchsiteCa2(Mg4Ti2)(Al4Si2)O20Tric. 1 : P1
9.DH.05LeucophaniteNaCaBeSi2O6FOrth. 222 : P212121
9.DH.10OhmiliteSr3(Ti,Fe3+)(Si4O12)(O,OH) · 2-3H2OMon. 2/m : P21/m
9.DH.15HaradaiteSrVSi2O7Orth. mmm(2/m2/m2/m)
9.DH.15SuzukiiteBaVSi2O7Orth.
9.DH.20Shcherbakovite(K,Ba)KNa(Ti,Nb)2(Si4O12)O2Orth. mmm(2/m2/m2/m) : Imma
9.DH.20BatisiteBaNaNaTi2(Si4O12)O2Orth. mmm(2/m2/m2/m) : Imma
9.DH.20NoonkanbahiteBaKNaTi2(Si4O12)O2Orth. mmm(2/m2/m2/m) : Imma
9.DH.25TaikaniteSr3BaMn2+2(Si4O12)O2Mon. 2 : B2
9.DH.30KrauskopfiteBaSi2O5 · 3H2OMon. 2/m : P21/b
9.DH.35GageiteMn21(Si4O12)2O3(OH)20Mon. 2/m
9.DH.35Balangeroite(Mg,Fe2+,Fe3+,Mn2+)42Si16O54(OH)40Mon. 2/m
9.DH.40KuratiteCa2(Fe2+5Ti)O2[Si4Al2O18]Tric. 1 : P1
9.DH.40AenigmatiteNa4[Fe2+10Ti2]O4[Si12O36]Tric. 1 : P1
9.DH.40DorriteCa4(Mg3Fe3+9)O4(Si3Al8Fe3+O36)Tric.
9.DH.40SerendibiteCa4[Mg6Al6]O4[Si6B3Al3O36]Tric. 1 : P1
9.DH.40RhöniteCa4[Mg8Fe3+2Ti2]O4[Si6Al6O36]Tric. 1 : P1
9.DH.40KhesiniteCa4(Mg3Fe3+9)O4(Fe3+9Si3)O36Tric. 1 : P1
9.DH.40'UM1991-29-SiO:FeMgNa'Na4(Mg5Fe3+7)O4[Si9Fe3+3O36]
9.DH.40HøgtuvaiteCa4[Fe2+6Fe3+6]O4[Si8Be2Al2O36]Tric. 1 : P1
9.DH.40'Leucorhönite'Ca2(Mg,Fe3+,Al)6(Si,Al)6O20Tric.
9.DH.40WelshiteCa4Mg9Sb3O4[Si6Be3AlFe2O36]Tric. 1 : P1
9.DH.40KrinoviteNa2Mg4Cr3+2(Si6O18)O2Tric. 1 : P1
9.DH.40Makarochkinite(Ca,Na)4[Fe2+8Fe3+2Ti2]O4[Si8Be2Al2O36]Tric. 1 : P1
9.DH.45SapphirineMg4(Mg3Al9)O4[Si3Al9O36]Mon. 2/m : P21/b
9.DH.50Khmaralite(Mg,Al,Fe)16[(Al,Si,Be)12O36]O4Mon. 2/m : P21/b
9.DH.55'UM1988-26-SiO:AlMg'Mg4Al2O[Si3Al2O15]
9.DH.55Surinamite(Mg,Fe)3Al4BeSi3O16Mon. 2/m
9.DH.60DeeriteFe2+6Fe3+3(Si6O17)O3(OH)5Mon. 2/m : P21/b
9.DH.65Taneyamalite(Na,Ca)Mn2+12(Si,Al)12(O,OH)44Tric.
9.DH.65HowieiteNa(Fe2+,Fe3+,Al,Mg)12(Si6O17)2(O,OH)10Tric. 1 : P1
9.DH.70JohninnesiteNa2Mn2+9Mg7(OH)8[AsO4]2[Si6O17]2Tric.
9.DH.75AgrelliteNaCa2Si4O10FTric. 1 : P1

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 WilkinsoniteHide

References for WilkinsoniteHide

Reference List:

Localities for WilkinsoniteHide

Showing 6 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.
Australia (TL)
 
  • New South Wales
Duggan (1990) +1 other reference
Brazil
 
  • Minas Gerais
Guarino et al. (2021)
Czech Republic
 
  • Karlovy Vary Region
    • Cheb District
      • Ovesné Kladruby
Jirasek et al. (2026)
Ethiopia
 
  • Oromia Region
Gaeta et al. (1991) +1 other reference
Mongolia
 
  • Khovd Province
    • Myangad District
      • Khaldzan Buragtag massif
Pavel M. Kartashov (n.d.)
Yemen
 
  • Hadhramaut Governorate
Zolensky et al. (2003)
 
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