Metastudtite
A valid IMA mineral species
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About Metastudtite
Franz E. Studt
Formula:
UO4 · 2H2O
Colour:
Pale yellow
Lustre:
Silky
Specific Gravity:
4.67 (Calculated)
Crystal System:
Orthorhombic
Name:
Named as a dehydration product of studtite. The root name is for Franz Edward Studt (or Stüdt) (30 November 1873, London, England, UK - 3 July 1953, Holborn, England, UK), geologist for Tanganyika Concessions Ltd. He prepared an important geological map of Katanga, published in 1913.
Unique Identifiers
Mindat ID:
2687
Long-form identifier:
mindat:1:1:2687:7
IMA Classification of Metastudtite
Classification of Metastudtite
4.GA.15
4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
G : Uranyl Hydroxides
A : Without additional cations
4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
G : Uranyl Hydroxides
A : Without additional cations
5.3.1.2
5 : OXIDES CONTAINING URANIUM OR THORIUM
3 : AXO4·xH2O
5 : OXIDES CONTAINING URANIUM OR THORIUM
3 : AXO4·xH2O
7.16.5
7 : Oxides and Hydroxides
16 : Oxides of U
7 : Oxides and Hydroxides
16 : Oxides of U
Mineral Symbols
As of 2021 there are now IMA–CNMNC approved mineral symbols (abbreviations) for each mineral species, useful for tables and diagrams.
| Symbol | Source | Reference for Standard |
|---|---|---|
| Mstu | IMA–CNMNC | Warr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43 |
Physical Properties of Metastudtite
Optical Data of Metastudtite
Type:
Biaxial (+)
RI values:
nα = 1.640(2) nβ = 1.658(2) nγ = 1.760(2)
2V:
Measured: 47° , Calculated: 48°
Max. Birefringence:
δ = 0.120
Based on recorded range of RI values above.
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.
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).
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.
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.
Dispersion:
r < v moderate
Optical Extinction:
Z = c (direction of elongation).
Pleochroism:
Not Visible
Chemistry of Metastudtite
Mindat Formula:
UO4 · 2H2O
Elements listed:
Crystallography of Metastudtite
Crystal System:
Orthorhombic
Class (H-M):
mmm(2/m2/m2/m) - Dipyramidal
Space Group:
Pnma
Cell Parameters:
a = 8.411(1) Å, b = 8.744(1) Å, c = 6.505(1) Å
Ratio:
a:b:c = 0.962 : 1 : 0.744
Unit Cell V:
478.39 ų
Z:
2
Morphology:
Fibrous, or as elongated tablets, to 3 mm; in nodules.
Comment:
Data from Rodriguez et al. (2016). Previously assumed to have space group Immm. "In light of the structure determination for studtite, it is likely that the correct unit cell of metastudtite is larger than previously thought, as the repeat length of the chain of uranyl polyhedra in studtite is 8.4 Å, and is not compatible with the 4.2 Å cell dimension" (Burns & Hughes, 2003).
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 5.22 Å | (100) |
| 4.38 Å | (50) |
| 3.79 Å | (50) |
| 3.538 Å | (80) |
| 3.214 Å | (50b) |
| 2.756 Å | (30) |
| 2.669 Å | (20) |
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Stage 7: Great Oxidation Event | <2.4 |
| 47a : [Near-surface hydration of prior minerals] | |
| Stage 10b: Anthropogenic minerals | <10 Ka |
| 57 : Other minerals formed by human processes |
Type Occurrence of Metastudtite
General Appearance of Type Material:
Aggregates of flexible pale yellow fibers. Also as elongated tablets.
Place of Conservation of Type Material:
Royal Museum of Central Africa, Tervuren, Belgium, RGM13748 and RGM13755.
Geological Setting of Type Material:
Secondary uranium mineral.
Associated Minerals at Type Locality:
Synonyms of Metastudtite
Other Language Names for Metastudtite
Common Associates
Associations Based on Photo Data:
| 4 photos of Metastudtite associated with Uranophane | Ca(UO2)2(SiO3OH)2 · 5H2O |
| 4 photos of Metastudtite associated with Wulfenite | Pb(MoO4) |
| 3 photos of Metastudtite associated with Becquerelite | Ca(UO2)6O4(OH)6 · 8H2O |
| 2 photos of Metastudtite associated with Phosphuranylite | KCa(H3O)3(UO2)7(PO4)4O4 · 8H2O |
| 2 photos of Metastudtite associated with Rutherfordine | (UO2)CO3 |
| 2 photos of Metastudtite associated with Uraninite | UO2 |
| 1 photo of Metastudtite associated with Soddyite | (UO2)2SiO4 · 2H2O |
| 1 photo of Metastudtite associated with Billietite | Ba(UO2)6O4(OH)6 · 4-8H2O |
| 1 photo of Metastudtite associated with Wölsendorfite | Pb7(UO2)14O19(OH)4 · 12H2O |
| 1 photo of Metastudtite associated with Masuyite | Pb(UO2)3O3(OH)2 · 3H2O |
Related Minerals - Strunz-mindat Grouping
| 4.GA.05 | Paraschoepite | UO3 · 2H2O |
| 4.GA.05 | Metaschoepite | (UO2)8O2(OH)12 · 10H2O |
| 4.GA.05 | Schoepite | (UO2)8O2(OH)12 · 12H2O |
| 4.GA.10 | Ianthinite | U4+(UO2)5O7 · 10H2O |
| 4.GA.15 | Studtite | [(UO2)(O2)(H2O)2] · H2O |
| 4.GA.20 | Paulscherrerite | UO2(OH)2 |
Radioactivity
Radioactivity:
| Element | % Content | Activity (Bq/kg) | Radiation Type |
|---|---|---|---|
| Uranium (U) | 70.4109% | 17,602,725 | 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: –
| Distance | Dose rate | Risk |
|---|---|---|
| 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
Fluorescence of Metastudtite
Not fluorescent.
Other Information
Notes:
Soluble without effervescence in hot HCl.
Radioactive.
Radioactive.
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 Metastudtite
mindat.org URL:
https://www.mindat.org/min-2687.html
Please feel free to link to this page.
Please feel free to link to this page.
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External Links:
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References for Metastudtite
Reference List:
Debets, P.C. (1963) X-ray diffraction data on hydrated uranium peroxide. Journal of Inorganic and Nuclear Chemistry, 25 (6) 727-730 doi:10.1016/0022-1902(63)80165-7(synthetic)
Deliens, Michel, Piret, Paul (1983) Metastudtite, UO4·2H2O, a new mineral from Shinkolobwe, Shaba, Zaire. American Mineralogist, 68 (3-4) 456-458
Localities for Metastudtite
Showing 6 localities.
symbol to view information about a locality.
The Locality List
- 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).
All localities listed without proper references should be considered as questionable.
DR Congo (TL) | |
| Deliens et al. (1983) +1 other reference |
| Gauthier et al. (1989) |
Namibia | |
| Bowell et al. (2017) |
Norway | |
| Husdal (2019) |
| Husdal (2023) |
Spain | |
| Desor (08/2020) |
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Shinkolobwe Mine, Shinkolobwe, Kambove Territory, Haut-Katanga, DR Congo