Schoepite
A valid IMA mineral species - grandfathered
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About Schoepite
Alfred Schoep
Formula:
(UO2)8O2(OH)12 · 12H2O
Colour:
Amber-yellow, lemon-yellow, or sulphur-yellow
Lustre:
Adamantine, Sub-Adamantine, Vitreous
Hardness:
2½
Specific Gravity:
4.8
Crystal System:
Orthorhombic
Member of:
Name:
Named by Thomas Leonard Walker in 1923 in honour of Alfred Schoep (6 June 1881, Ghent, Belgium - 1 June 1966, Ghent, Belgium), Professor of Mineralogy, University of Ghent, Belgium.
May originate as a dehydration product of ianthinite, and may itself dehydrate to metaschoepite and, subsequently, to paulscherrerite.
Most stable uranyl-bearing phase at moderate H2O2 activity. At high concentrations of H2O2, the stability path is as follows: studtite, schoepite, metaschoepite, becquerelite.
Most stable uranyl-bearing phase at moderate H2O2 activity. At high concentrations of H2O2, the stability path is as follows: studtite, schoepite, metaschoepite, becquerelite.
Unique Identifiers
Mindat ID:
3574
Long-form identifier:
mindat:1:1:3574:9
Similar Names
| Schoenite | A synonym of Picromerite |
IMA Classification of Schoepite
Approved, 'Grandfathered' (first described prior to 1959)
IMA Formula:
(U6+O2)4O(OH)6(H2O)6
Classification of Schoepite
4.GA.05
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
5.2.1.3
5 : OXIDES CONTAINING URANIUM OR THORIUM
2 : AXO3·xH2O
5 : OXIDES CONTAINING URANIUM OR THORIUM
2 : AXO3·xH2O
7.16.2
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 |
|---|---|---|
| Sho | 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 Schoepite
Adamantine, Sub-Adamantine, Vitreous
Transparency:
Transparent
Colour:
Amber-yellow, lemon-yellow, or sulphur-yellow
Streak:
Yellow
Hardness:
2½ on Mohs scale
Tenacity:
Brittle
Cleavage:
Perfect
{001} perfect; {010} poor
{001} perfect; {010} poor
Density:
4.8 g/cm3 (Measured) 4.918 g/cm3 (Calculated)
Optical Data of Schoepite
Type:
Biaxial (-)
RI values:
nα = 1.69 - 1.700 nβ = 1.714 - 1.720 nγ = 1.735
2V:
Measured: 89°
Birefringence:
0.04
Max. Birefringence:
δ = 0.035 - 0.045
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:
weak to moderate
Optical Extinction:
Parallel
Pleochroism:
Visible
Comments:
X = c = Colourless
Y = b = Lemon-yellow
Z = a = Lemon-yellow
Y = b = Lemon-yellow
Z = a = Lemon-yellow
Chemistry of Schoepite
Mindat Formula:
(UO2)8O2(OH)12 · 12H2O
Elements listed:
Crystallography of Schoepite
Crystal System:
Orthorhombic
Class (H-M):
mmm(2/m2/m2/m) - Dipyramidal
Space Group:
Pbca
Setting:
Pbca
Cell Parameters:
a = 16.7810(5) Å, b = 14.7044(4) Å, c = 14.2985(5) Å
Ratio:
a:b:c = 1.141 : 1 : 0.972
Unit Cell V:
3528.22 ų
Z:
8
Morphology:
Usually tabular {001}; also equant or short prismatic [001].
Comment:
The space-group Pbca confirmed by the new structure determination and refinement; the formula is [(UO2)4O(OH)6](H2O)6 for Z = 8 (Plášil 2018)
Crystal Structure
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Data courtesy of the American Mineralogist Crystal Structure Database. Click on an AMCSD ID to view structure
| ID | Species | Reference | Link | Year | Locality | Pressure (GPa) | Temp (K) |
|---|---|---|---|---|---|---|---|
| 0005517 | Schoepite | Finch R J, Cooper M A, Hawthorne F C, Ewing R C (1996) The crystal structure of schoepite, [(UO2)8O2(OH)12](H2O)12 The Canadian Mineralogist 34 1071-1088 |  | 1996 | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 7.28 Å | (100) |
| 5.08 Å | (70) |
| 3.66 Å | (10) |
| 3.51 Å | (10) |
| 3.44 Å | (20) |
| 3.22 Å | (10) |
| 2.89 Å | (10) |
| 2.54 Å | (19) |
Comments:
ICDD 13-407
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Near-surface Processes | |
| 27 : Radioactive decay; auto-oxidation | |
| Stage 7: Great Oxidation Event | <2.4 |
| 47a : [Near-surface hydration of prior minerals] | |
| 47f : [Uranyl (U⁶⁺) minerals] |
Type Occurrence of Schoepite
Geological Setting of Type Material:
Oxidized zone of a copper-uranium deposit
Synonyms of Schoepite
Other Language Names for Schoepite
Relationship of Schoepite to other Species
Member of:
Other Members of Schoepite Group:
| Metaschoepite | (UO2)8O2(OH)12 · 10H2O | Orth. mmm(2/m2/m2/m) : Pbcn |
| Paulscherrerite | UO2(OH)2 | Mon. |
Common Associates
Associations Based on Photo Data:
| 88 photos of Schoepite associated with Rutherfordine | (UO2)CO3 |
| 52 photos of Schoepite associated with Malachite | Cu2(CO3)(OH)2 |
| 47 photos of Schoepite associated with Cuprosklodowskite | Cu(UO2)2(SiO3OH)2 · 6H2O |
| 41 photos of Schoepite associated with Uraninite | UO2 |
| 31 photos of Schoepite associated with Ianthinite | U4+(UO2)5O7 · 10H2O |
| 31 photos of Schoepite associated with Digenite | Cu9S5 |
| 21 photos of Schoepite associated with Curite | Pb3(H2O)2[(UO2)4O4(OH)3]2 |
| 18 photos of Schoepite associated with Uranophane | Ca(UO2)2(SiO3OH)2 · 5H2O |
| 15 photos of Schoepite associated with Zircon | Zr(SiO4) |
| 15 photos of Schoepite associated with Metatorbernite | Cu(UO2)2(PO4)2 · 8H2O |
Related Minerals - Strunz-mindat Grouping
| 4.GA.05 | Paraschoepite | UO3 · 2H2O |
| 4.GA.05 | Metaschoepite | (UO2)8O2(OH)12 · 10H2O |
| 4.GA.10 | Ianthinite | U4+(UO2)5O7 · 10H2O |
| 4.GA.15 | Metastudtite | UO4 · 2H2O |
| 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) | 72.8895% | 18,222,375 | 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 Schoepite
Pale green SW and LW
Other Information
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 Schoepite
mindat.org URL:
https://www.mindat.org/min-3574.html
Please feel free to link to this page.
Please feel free to link to this page.
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External Links:
Mineral Dealers:
References for Schoepite
Reference List:
Walker, T. L. (1923) Schoepite, a new uranium mineral from Kasolo, Belgian Congo. American Mineralogist, 8 (4) 67-69
Schoep, Alfred (1923) Sur la forme cristalline de la becquerélite et de la schoepite ; sur leur composition chimique et sur le polymorphisme de l'hydroxyde d'uranium UO3.2H2O. Bulletin de Minéralogie, 46 (1) 9-18 doi:10.3406/bulmi.1923.3804
Palache, Charles (1934) Crystallography of the uranium oxides. American Mineralogist, 19 (7) 309-315 p.310
Schoep, Alfred, Stradiot, Sadi (1947) Paraschoepite and epiianthinite, two new uranium minerals from Shinkolobwe (Belgian Congo) American Mineralogist, 32 (5-6) 344-350 [as epiianthinite]
Christ, C. L., Clark, J. R. (1960) Crystal chemical studies of some uranyl oxide hydrates. American Mineralogist, 45 (9-10) 1026-1061
Christ, C. L. (1965) Phase transformations and crystal chemistry of schoepite. American Mineralogist, 50 (1-2) 235-239
Vochten, R., Van Haverbeke, L. (1990) Transformation of schoepite into the uranyl oxide hydrates: Becquerelite, billietite and wölsendorfite. Mineralogy and Petrology, 43 (1) 65-72 doi:10.1007/bf01164222
Finch, Robert J., Cooper, Mark A., Hawthorne, Frank C., Ewing, Rodney C. (1996) The crystal structure of schoepite, [(UO2)8O2(OH)12](H2O)12. The Canadian Mineralogist, 34 (5) 1071-1088
Finch, Robert J., Hawthorne, Frank C., Miller, M. L., Ewing, R. C. (1997) Distinguishing among schoepite, [(UO2)8O2(OH)12](H2O)12, and related minerals by X-ray powder diffraction. Powder Diffraction, 12 (4) 230-238 doi:10.1017/s0885715600009799
Weller, Mark. T., Light, Mark E., Gelbrich, Thomas (2000) Structure of uranium(VI) oxide dihydrate, UO3·2H2O; synthetic meta-schoepite (UO2)4O(OH)6·5H2O. Acta Crystallographica Section B Structural Science, 56 (4). 577-583 doi:10.1107/s0108768199016559[comparison with schoepite]
Burns, Peter C. (2005) U6+ minerals and inorganic compounds: insights into an expanded structural hierarchy of crystal structures. The Canadian Mineralogist, 43 (6) 1839-1894 doi:10.2113/gscanmin.43.6.1839
Plášil, J. (2018) The crystal structure of uranyl-oxide mineral schoepite, [(UO2)4O(OH)6](H2O)6, revisited. Journal of Geosciences, 65-73 doi:10.3190/jgeosci.252
Colmenero, Francisco, Fernández, Ana María, Timón, Vicente, Cobos, Joaquin (2018) Becquerelite mineral phase: crystal structure and thermodynamic and mechanical stability by using periodic DFT. RSC Advances, 8 (43). 24599-24616 doi:10.1039/c8ra04678f
Localities for Schoepite
Showing 120 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.
Argentina | |
| Mr. Nelson Valenzuela. |
Australia | |
| D.A.Berkman (1968) |
| Brugger et al. (2003) |
| Bottrill (2021) +1 other reference |
Brazil | |
| Pires et al. (2014) |
Canada | |
| Cowan (1962) |
| Chatterjee (1977) |
| Reiner Mielke and Travis Olds |
China | |
| Long Lu et al. (2006) |
Czech Republic | |
| Plášil |
| - (Pavel Škácha coll.) | |
| Plášil et al. (2026) |
| Hloušek et al. (2002) |
| Plášil et al. (2014) |
| |
| Hyrsl et al. (2009) | |
DR Congo (TL) | |
| Christ (1965) +2 other references |
| |
| Deliens (1996) +1 other reference |
| Lavinsky (n.d.) |
Egypt | |
| El-Naby (2009) |
| Hussein et al. (1988) | |
France | |
| - (1998) |
| J.-J. Périchaud: "Où trouver les minéraux d'Auvergne" et al. (Clermont-Ferrand) | |
| - (1998) |
| Queneau (n.d.) |
| Lièvre et al. (2002) |
| Lièvre et al. (2002) |
| - (1998) |
| - (1998) | |
| - (1998) |
| Bariand et al. (1993) +1 other reference |
| Henriot et al. (1998) |
| - (1998) | |
Gabon | |
| Janusz Janeczek (1999) |
Germany | |
| Walenta (1992) |
| Walenta (1989) +1 other reference |
| Walenta (1992) |
| |
| Dill et al. (2010) | |
| Aufschluss 69/ (7+8) +1 other reference |
| Lapis 30 (7/8) |
Hungary | |
| Szakáll et al. (1996) |
| Szakáll et al. (1996) |
Italy | |
| Daniele Ravagnani - I giacimenti ... |
| De Michele V. (1979) |
| Piccoli et al. (2007) |
| Piccoli et al. (2007) |
| luigi chiapino |
| Ravagnani (1974) |
| Campostrini et al. (2006) |
| Campostrini et al. (2005) |
Japan | |
| Akira Kato (1973) |
Mexico | |
| Murphy (2006) |
| www.swri.org (2001) +1 other reference | |
Namibia | |
| Bowell et al. (2017) |
New Zealand | |
| Christie et al. (2000) |
Norway | |
| Neumann (1985) |
| Neumann (1985) | |
Pakistan | |
| Alia et al. (2018) |
Poland | |
| Syczewski et al. (2023) |
Russia | |
| Pavel M. Kartashov (n.d.) |
| Pavel M. Kartashov (n.d.) |
Spain | |
| Joan Abella i Creus specimens |
| www.foro-minerales.com (n.d.) |
| www.foro-minerales.com (n.d.) | |
| www.foro-minerales.com (n.d.) |
Switzerland | |
| Stalder et al. (1998) |
| Meisser (2012) |
Tajikistan | |
| Pekov (1998) |
UK | |
| Braithwaite et al. (1990) |
| Knight (1978) +2 other references | |
| R. S. W. Braithwaite and J. R. Knight (1990) +1 other reference |
Ukraine | |
| Burakov et al. () +1 other reference |
USA | |
| Frondel (1956) +2 other references |
| Bollin et al. (1958) |
| Austin (1964) +1 other reference | |
| Granger (1962) +1 other reference |
| Eckel et al. (1997) |
| Eckel et al. (1997) |
| Eckel et al. (1997) |
| Eckel et al. (1997) |
| Eckel et al. (1997) | |
| Eckel et al. (1997) |
| Gross (1965) +2 other references |
| Travis Olds collection |
| Eckel et al. (1997) | |
| King et al. (1994) |
| King (2009) |
| King (2009) | |
| Fred Davis discovery specimen and ... |
| Falster et al. (2019) |
| King et al. (1994) |
| King et al. (6) | |
| King et al. (6) | |
| King (2000) +1 other reference |
| |
| King et al. (1994) +1 other reference | |
| Frondel (1956) |
| Whitmore et al. (2004) |
| Januzzi et al. (1976) |
| Northrop et al. (1996) |
| NMBMMR Memoir 15 Geology and Technology ... | |
| Caldwell (2018) | |
| Foord et al. (1997) |
| Curt segeler |
| Smith (1991) |
| MINERALS OF THE KARNES URANIUM ... | |
| Bullock (1981) |
| Page et al. (1956) +3 other references | |
| Bullock (1981) |
| Bullock (1981) |
| Bullock (1981) | |
| USGS TEI #514 +2 other references | |
| Min News 16:1 p1 | |
| Bullock (1981) |
| Sumaila (2017) |
| USGS MRDS Database |
| Am Min 51:1567-1578 | |
Uzbekistan | |
| Frost et al. (2009) |
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Musonoi Mine, Kolwezi, Mutshatsha, Lualaba, DR Congo