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⇱ Oursinite: Mineral information, data and localities.

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Oursinite

A valid IMA mineral species
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About OursiniteHide

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Formula:
Co(UO2)2(SiO3OH)2 · 6H2O
All material so far seems to contain minor Mg replacing Co.
Colour:
Pale yellow
Hardness:
3 - 3½
Specific Gravity:
3.674 (Calculated)
Crystal System:
Orthorhombic
Name:
From the french oursin, in allusion to its appearance like a sea urchin
This page provides mineralogical data about Oursinite.


Unique IdentifiersHide

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Mindat ID:
3047
Long-form identifier:
mindat:1:1:3047:8

IMA Classification of OursiniteHide

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Approved
Approval year:
1982
First published:
1983

Classification of OursiniteHide

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9.AK.10

9 : SILICATES (Germanates)
A : Nesosilicates
K : Uranyl neso- and polysilicates
53.3.1.7

53 : NESOSILICATES Insular SiO4 Groups and Other Anions or Complex Cations
3 : Insular SiO4 Groups and Other Anions of Complex Cations with (UO2)
14.16.19

14 : Silicates not Containing Aluminum
16 : Silicates of U

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.

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

Physical Properties of OursiniteHide

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Transparency:
Transparent
Colour:
Pale yellow
Hardness:
3 - 3½ on Mohs scale
Cleavage:
Distinct/Good
on {hk0}
Density:
3.674 g/cm3 (Calculated)

Optical Data of OursiniteHide

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Type:
Biaxial (-)
RI values:
nα = 1.624 nβ = 1.64 nγ = 1.65
2V:
Measured: 76° , Calculated: 76°
Max. Birefringence:
δ = 0.026
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.

Surface Relief:
Moderate
Dispersion:
weak

Chemistry of OursiniteHide

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Mindat Formula:
Co(UO2)2(SiO3OH)2 · 6H2O

All material so far seems to contain minor Mg replacing Co.
Element Weights:
Element% weight
U53.294 %
O32.240 %
Co6.598 %
Si6.288 %
H1.580 %

Calculated from ideal end-member formula.
Common Impurities:
Ni

Crystallography of OursiniteHide

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Crystal System:
Orthorhombic
Class (H-M):
mmm(2/m2/m2/m) - Dipyramidal
Space Group:
Cmca
Cell Parameters:
a = 7.0457(4) Å, b = 17.5445(8) Å, c = 12.7231(2) Å
Ratio:
a:b:c = 0.402 : 1 : 0.725
Unit Cell V:
1,572.74 ų (Calculated from Unit Cell)
Z:
4
Morphology:
Radiating aggregates of acicular crystals to 1mm.
Comment:
Cell parameters from Plášil (2018) with R1=2.03%.

Crystal StructureHide

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Data courtesy of the American Mineralogist Crystal Structure Database. Click on an AMCSD ID to view structure
IDSpeciesReferenceLinkYearLocalityPressure (GPa)Temp (K)
0004122OursiniteKabatko K A, Burns P C (2006) A novel arrangement of silicate tetrahedra in the uranyl silicate sheet of oursinite, (Co0.8Mg0.2)[(UO2)(SiO3OH)]2(H2O)6 American Mineralogist 91 333-336👁 Image
20060293
CIF Raw Data - click here to close

X-Ray Powder DiffractionHide

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Powder Diffraction Data:
d-spacingIntensity
8.73 Å(100)
7.20 Å(70)
5.16 Å(50)
4.55 Å(35)
4.141 Å(70)
3.528 Å(40)
3.267 Å(30)
2.853 Å(90)

Geological EnvironmentHide

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Paragenetic Mode(s):
Paragenetic ModeEarliest Age (Ga)
Stage 7: Great Oxidation Event<2.4
47a : [Near-surface hydration of prior minerals]
47f : [Uranyl (U⁶⁺) minerals]

Type Occurrence of OursiniteHide

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General Appearance of Type Material:
Radial aggregates of pale yellow acicular crystals, with maximum dimensions 1 x 0.02 x 0.02 mm.
Place of Conservation of Type Material:
Royal Museum of Central Africa, Tervuren, Belgium, RGM1321.
Geological Setting of Type Material:
Uranium deposit; brecciated dolomite.
Associated Minerals at Type Locality:

Synonyms of OursiniteHide

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Other Language Names for OursiniteHide

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Dutch:Oursiniet
German:Oursinit
Spanish:Oursinita

Relationship of Oursinite to other SpeciesHide

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Other Members of Sklodowskite Group:
CuprosklodowskiteCu(UO2)2(SiO3OH)2 · 6H2OTric. 1 : P1
SklodowskiteMg(UO2)2(SiO3OH)2 · 6H2OMon. 2/m : B2/m

Common AssociatesHide

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Associations Based on Photo Data:
1 photo of Oursinite associated with WölsendorfitePb7(UO2)14O19(OH)4 · 12H2O
1 photo of Oursinite associated with UranophaneCa(UO2)2(SiO3OH)2 · 5H2O
1 photo of Oursinite associated with UraniniteUO2
1 photo of Oursinite associated with SklodowskiteMg(UO2)2(SiO3OH)2 · 6H2O
1 photo of Oursinite associated with Rutherfordine(UO2)CO3
1 photo of Oursinite associated with BecquereliteCa(UO2)6O4(OH)6 · 8H2O
1 photo of Oursinite associated with HeterogeniteCo3+O(OH)

Related Minerals - Strunz-mindat GroupingHide

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9.AK.OrlitePb3(UO2)3(Si2O7)2 · 6H2O
9.AK.05Soddyite(UO2)2SiO4 · 2H2OOrth. mmm(2/m2/m2/m) : Fddd
9.AK.10SklodowskiteMg(UO2)2(SiO3OH)2 · 6H2OMon. 2/m : B2/m
9.AK.10CuprosklodowskiteCu(UO2)2(SiO3OH)2 · 6H2OTric. 1 : P1
9.AK.15ParauranophaneCa(UO2)2(SiO3OH)2 · 5H2OMon. 2/m : P21/b
9.AK.15UranophaneCa(UO2)2(SiO3OH)2 · 5H2OMon. 2 : P21
9.AK.15NatroboltwooditeNa(UO2)(SiO3OH) · H2OOrth. 222 : P212121
9.AK.15KasolitePb(UO2)(SiO4) · H2OMon. 2/m : P21/b
9.AK.15Boltwoodite(K,Na)(UO2)(SiO3OH) · 1.5H2OMon. 2 : P21
9.AK.20Swamboite-(Nd)Nd0.333[(UO2)(SiO3OH)](H2O)~2.5Mon. 2/m : P21/b
9.AK.25HaiweeiteCa(UO2)2[Si5O12(OH)2] · 6H2OOrth. mmm(2/m2/m2/m) : Pbcn
9.AK.25MetahaiweeiteCa(UO2)2Si6O15 · nH2OMon. 2/m : P2/b
9.AK.30WeeksiteK2(UO2)2(Si5O13) · 4H2OMon. 2/m : B2/m
9.AK.30CoutinhoiteThxBa(1-2x)(UO2)2Si5O13 · (H2O)1+y (0 < x < 0.5 and 0 < y < (2+x))Orth. mmm(2/m2/m2/m)
9.AK.30Barronite(◻0.5Ba0.5)(UO2)2Si5O12(OH) · 2H2OMon. 2/m : B2/m
9.AK.35MagnioursiliteMg4(UO2)4(Si2O5)5(OH)6 · 20H2O
9.AK.35CalcioursiliteCa4(UO2)4(Si2O5)5(OH)6 · 15H2OOrth.
9.AK.40UranosiliteUO3 · 7SiO2Orth.

RadioactivityHide

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Radioactivity:
Element % Content Activity (Bq/kg) Radiation Type
Uranium (U) 53.2943% 13,323,575 α, β, γ
Thorium (Th) 0.0000% 0 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

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Health Risks:
Radioactive

Internet Links for OursiniteHide

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mindat.org URL:
https://www.mindat.org/min-3047.html
Please feel free to link to this page.

References for OursiniteHide

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Reference List:

Localities for OursiniteHide

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Showing 2 localities.

This map shows a selection of localities that have latitude and longitude coordinates recorded. Click on the 👁 Image
symbol to view information about a locality. The 👁 Image
symbol next to localities in the list can be used to jump to that position on the map.

Locality ListHide

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👁 Image
- This locality has map coordinates listed. 👁 Image
- This locality has estimated coordinates. ⓘ - Click for references and further information on this occurrence. ? - Indicates mineral may be doubtful at this locality. 👁 Image
- Good crystals or important locality for species. 👁 Image
- 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.
DR Congo (TL)
  • Haut-Katanga
    • Kambove Territory
      • Shinkolobwe
edit.africamuseum.be (n.d.) +2 other references
  • Lualaba
    • Mutshatsha
      • Kolwezi
Wilson (2018)
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