Uranophane
A valid IMA mineral species - grandfathered
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About Uranophane
Formula:
Ca(UO2)2(SiO3OH)2 · 5H2O
Colour:
Light yellow, lemon-yellow, honey-yellow, straw-yellow, green-yellow
Lustre:
Vitreous, Greasy, Silky, Dull, Earthy
Hardness:
2 - 3
Specific Gravity:
3.8 - 3.91
Crystal System:
Monoclinic
Member of:
Name:
Named in 1853 by Christian Friedrich Martin Websky for the chemical composition containing URANium plus Greek φαίνεσθαι "phainesthai", to appear, in allusion to the uncertainty of its composition as originally determined. Long named uranophane-α to distinguish it from its polymorph uranophane-β, it was renamed in 2022 by the IMA to simply uranophane.
Type Locality:
Polymorph of:
Unique Identifiers
Mindat ID:
4107
Long-form identifier:
mindat:1:1:4107:8
Similar Names
| β-Uranophane | A synonym of Parauranophane |
IMA Classification of Uranophane
Approved, 'Grandfathered' (first described prior to 1959)
IMA status notes:
Renamed by the IMA
IMA Formula:
Ca(U6+O2)2(SiO3OH)2·5H2O
First published:
1853
Classification of Uranophane
9.AK.15
9 : SILICATES (Germanates)
A : Nesosilicates
K : Uranyl neso- and polysilicates
9 : SILICATES (Germanates)
A : Nesosilicates
K : Uranyl neso- and polysilicates
53.3.1.2
53 : NESOSILICATES Insular SiO4 Groups and Other Anions or Complex Cations
3 : Insular SiO4 Groups and Other Anions of Complex Cations with (UO2)
53 : NESOSILICATES Insular SiO4 Groups and Other Anions or Complex Cations
3 : Insular SiO4 Groups and Other Anions of Complex Cations with (UO2)
14.16.10
14 : Silicates not Containing Aluminum
16 : Silicates of U
14 : Silicates not Containing Aluminum
16 : Silicates 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.
Please only use the official IMA–CNMNC symbol. Older variants are listed for historical use only.
Please only use the official IMA–CNMNC symbol. Older variants are listed for historical use only.
| Symbol | Source | Reference for Standard |
|---|---|---|
| Urp-α | IMA–CNMNC | Warr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43 |
| Urp | The Canadian Mineralogist (2019) | The Canadian Mineralogist (2019) The Canadian Mineralogist list of symbols for rock- and ore-forming minerals (December 30, 2019). download |
Pronunciation of Uranophane
Pronunciation:
| Play | Recorded by | Country |
|---|---|---|
| Jolyon Ralph | United Kingdom |
Physical Properties of Uranophane
Vitreous, Greasy, Silky, Dull, Earthy
Transparency:
Transparent, Translucent
Comment:
Pearly on cleavage, waxy or dull when massive
Colour:
Light yellow, lemon-yellow, honey-yellow, straw-yellow, green-yellow
Hardness:
2 - 3 on Mohs scale
Tenacity:
Brittle
Cleavage:
Perfect
on {100}
on {100}
Density:
3.8 - 3.91 g/cm3 (Measured) 3.78 g/cm3 (Calculated)
Optical Data of Uranophane
Type:
Biaxial (-)
RI values:
nα = 1.643 nβ = 1.666 nγ = 1.669
2V:
Measured: 32° to 45°, Calculated: 38°
Max. Birefringence:
δ = 0.026
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 strong
Pleochroism:
Weak
Comments:
X= colorless
Y= pale canary yellow
Z= canary yellow
Y= pale canary yellow
Z= canary yellow
Chemistry of Uranophane
Mindat Formula:
Ca(UO2)2(SiO3OH)2 · 5H2O
Element Weights:
Crystallography of Uranophane
Crystal System:
Monoclinic
Class (H-M):
2 - Sphenoidal
Space Group:
P21
Cell Parameters:
a = 15.909(6) Å, b = 7.002(3) Å, c = 6.665(3) Å
β = 97.27(4)°
β = 97.27(4)°
Ratio:
a:b:c = 2.272 : 1 : 0.952
Unit Cell V:
736.48 ų (Calculated from Unit Cell)
Z:
2
Morphology:
Composite needles, stellate aggregates, fibrous or felted crusts, massive.
Comment:
Cell from Ginderow (1988).
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) |
|---|---|---|---|---|---|---|---|
| 0018734 | Uranophane | Barinova A V, Rastsvetaeva R K, Sidorenko G A, Verin I A (2003) Crystal structure of beta-uranophane from the Transbaikal region and its relation to the structure of the alpha modification Crystallography Reports 48 12-15 | 2003 | Transbaikal region, Russia | 0 | 293 | |
| 0018695 | Uranophane | Barinova A V, Rastsvetaeva R K, Sidorenko G A, Verin I A (2003) Crystal structure of beta-uranophane from the Transbaikal region and its relation to the structure of the a modification Crystallography Reports 48 12-15 | 2003 | Streltsovkii ore field, Transbaikal region, Russia | 0 | 293 | |
| 0012507 | Uranophane | Barinova A V, Rastsvetaeva R K, Sidorenko G A, Pushcharovsky D Y (2001) Crystal structure of high-symmetry alpha-uranophane Doklady Chemistry 378 122-124 | 2001 | Strel'tsovskii ore field, Transbaikal region, Russia | 0 | 293 | |
| 0010068 | Uranophane | Ginderow D (1988) Structure de l'uranophane alpha, Ca(UO2)2(SiO3OH)2*5H2O Acta Crystallographica C44 421-424 |  | 1988 | Bois Noirs du Puy-de-Dome, France | 0 | 293 |
| 0001061 | Uranophane | Viswanathan K, Harneit O (1986) Refined crystal structure of beta-uranophane, Ca(UO2)2(SiO3OH)2.5H2O American Mineralogist 71 1489-1493 |  | 1986 | Roessing, South-West Africa | 0 | 293 |
| 0000837 | Uranophane | Stohl F V, Smith D K (1981) The crystal chemistry of the uranyl silicate minerals American Mineralogist 66 610-625 | | 1981 | Shinkolobwe, Katanga | 0 | 293 |
| 0000081 | Uranophane | Smith D K, Gruner J W, Lipscomb W N (1957) The crystal structure of uranophane [Ca(H3O)2](UO2)2(SiO4)2.3H2O American Mineralogist 42 594-618 | | 1957 | Chinkolobwe deposits, Belgian Congo, Africa | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 7.88 Å | (100) |
| 3.94 Å | (90) |
| 2.99 Å | (80) |
| 2.91 Å | (80) |
| 1.969 Å | (70) |
| 4.76 Å | (50) |
| 3.20 Å | (50) |
| 2.63 Å | (50) |
| 2.10 Å | (50) |
| 6.61 Å | (40) |
| 5.42 Å | (40) |
| 3.60 Å | (40) |
| 3.51 Å | (40) |
| 2.69 Å | (40) |
| 2.20 Å | (40) |
Comments:
Ruggles pegmatite, New Hampshire, USA. Data from Frondel et al. (1956).
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Stage 7: Great Oxidation Event | <2.4 |
| 47a : [Near-surface hydration of prior minerals] | |
| 47f : [Uranyl (U⁶⁺) minerals] | |
| Stage 10b: Anthropogenic minerals | <10 Ka |
| 55 : Anthropogenic mine minerals | |
| 57 : Other minerals formed by human processes |
Geological Setting:
Secondary mineral in uranium deposits and pegmatites.
Type Occurrence of Uranophane
Place of Conservation of Type Material:
Holotype - Mineralogical Museum of the Institute of Geological Science, University of Wrocław, Wrocław, Poland.
Synonyms of Uranophane
Other Language Names for Uranophane
Relationship of Uranophane to other Species
Member of:
Other Members of Uranophane Group:
| Boltwoodite | (K,Na)(UO2)(SiO3OH) · 1.5H2O | Mon. 2 : P21 |
| Natroboltwoodite | Na(UO2)(SiO3OH) · H2O | Orth. 222 : P212121 |
| Parauranophane | Ca(UO2)2(SiO3OH)2 · 5H2O | Mon. 2/m : P21/b |
Common Associates
Associations Based on Photo Data:
| 213 photos of Uranophane associated with Uraninite | UO2 |
| 78 photos of Uranophane associated with Malachite | Cu2(CO3)(OH)2 |
| 65 photos of Uranophane associated with Fourmarierite | Pb(UO2)4O3(OH)4 · 4H2O |
| 64 photos of Uranophane associated with Rutherfordine | (UO2)CO3 |
| 63 photos of Uranophane associated with Haiweeite | Ca(UO2)2[Si5O12(OH)2] · 6H2O |
| 53 photos of Uranophane associated with Quartz | SiO2 |
| 45 photos of Uranophane associated with Studtite | [(UO2)(O2)(H2O)2] · H2O |
| 43 photos of Uranophane associated with Fluorite | CaF2 |
| 41 photos of Uranophane associated with Albite | Na(AlSi3O8) |
| 41 photos of Uranophane associated with Kasolite | Pb(UO2)(SiO4) · H2O |
Related Minerals - Strunz-mindat Grouping
| 9.AK. | 'Orlite' | Pb3(UO2)3(Si2O7)2 · 6H2O |
| 9.AK.05 | Soddyite | (UO2)2SiO4 · 2H2O |
| 9.AK.10 | Sklodowskite | Mg(UO2)2(SiO3OH)2 · 6H2O |
| 9.AK.10 | Cuprosklodowskite | Cu(UO2)2(SiO3OH)2 · 6H2O |
| 9.AK.10 | Oursinite | Co(UO2)2(SiO3OH)2 · 6H2O |
| 9.AK.15 | Parauranophane | Ca(UO2)2(SiO3OH)2 · 5H2O |
| 9.AK.15 | Natroboltwoodite | Na(UO2)(SiO3OH) · H2O |
| 9.AK.15 | Kasolite | Pb(UO2)(SiO4) · H2O |
| 9.AK.15 | Boltwoodite | (K,Na)(UO2)(SiO3OH) · 1.5H2O |
| 9.AK.20 | Swamboite-(Nd) | Nd0.333[(UO2)(SiO3OH)](H2O)~2.5 |
| 9.AK.25 | Haiweeite | Ca(UO2)2[Si5O12(OH)2] · 6H2O |
| 9.AK.25 | Metahaiweeite | Ca(UO2)2Si6O15 · nH2O |
| 9.AK.30 | Weeksite | K2(UO2)2(Si5O13) · 4H2O |
| 9.AK.30 | Coutinhoite | ThxBa(1-2x)(UO2)2Si5O13 · (H2O)1+y (0 < x < 0.5 and 0 < y < (2+x)) |
| 9.AK.30 | Barronite | (◻0.5Ba0.5)(UO2)2Si5O12(OH) · 2H2O |
| 9.AK.35 | Magnioursilite | Mg4(UO2)4(Si2O5)5(OH)6 · 20H2O |
| 9.AK.35 | Calcioursilite | Ca4(UO2)4(Si2O5)5(OH)6 · 15H2O |
| 9.AK.40 | Uranosilite | UO3 · 7SiO2 |
Radioactivity
Radioactivity:
| Element | % Content | Activity (Bq/kg) | Radiation Type |
|---|---|---|---|
| Uranium (U) | 55.5888% | 13,897,200 | 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 Uranophane
Weakly green, usually not fluorescent when massive.
Other Information
Health Risks:
Contains uranium - always wash hands after handling. Avoid inhaling dust when handling or breaking. Never lick or ingest. Avoid prolonged exposure in proximity of the body. Store away from inhabited areas.
Internet Links for Uranophane
mindat.org URL:
https://www.mindat.org/min-4107.html
Please feel free to link to this page.
Please feel free to link to this page.
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References for Uranophane
Reference List:
Gorman, D. H., Nuffield, E. W. (1955) Studies of radioactive compounds: VIII-Uranophane and beta-uranophane. American Mineralogist, 40 (7-8) 634-645
Frondel, C.; Riska, D.; Frondel, J.D. (1956) X-ray powder data for uranium and thorium minerals. Bulletin 1036g. US Geological Survey doi:10.3133/b1036g
Stohl, Frances V., Smith, Deane K. (1981) The crystal chemistry of the uranyl silicate minerals. American Mineralogist, 66 (5-6) 610-624
Ginderow, D. (1988) Structure de l'uranophane alpha, Ca(UO2)2(SiO3OH)2·5H2O. Acta Crystallographica Section C Crystal Structure Communications, 44 (3) 421-424 doi:10.1107/s0108270187011491
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
Sureda, R.; Casas, I.; Giménez, J.; de Pablo, J.; Quiñones, J.; Zhang, J.; Ewing, R. C. (2011) Effects of Ionizing Radiation and Temperature on Uranyl Silicates: Soddyite (UO2)2(SiO4)(H2O)2 and Uranophane Ca(UO2)2(SiO3OH)2·5H2O. Environmental Science & Technology, 45 (6). 2510-2515 doi:10.1021/es1041496
Colmenero, Francisco, Timón, Vicente, Bonales, Laura J., Cobos, Joaquín (2018) Structural, mechanical and Raman spectroscopic characterization of the layered uranyl silicate mineral, uranophane-α, by density functional theory methods. Clay Minerals, 53 (3) 377-392 doi:10.1180/clm.2018.27
Plášil, Jakub (2018) Structural complexity of uranophane and uranophane-β: implications for their formation and occurrence. European Journal of Mineralogy, 30 (2) 253-257 doi:10.1127/ejm/2017/0029-2691
Espriu-Gascon, Alexandra, Giménez, Javier, Casas, Ignasi, de Pablo, Joan (2018) Retention of cesium and strontium by uranophane, Ca(UO2)2(SiO3OH)2·5H2O. Journal of Hazardous Materials, 353. 431-435 doi:10.1016/j.jhazmat.2018.04.051
Frankland, Victoria L., Rickman, Sam P., Milodowski, Antoni E., Read, David (2022) Characterisation of Uranophane and Boltwoodite by Raman, luminescence and laser-induced breakdown spectroscopy. Applied Geochemistry, 138. 105183 doi:10.1016/j.apgeochem.2021.105183
Miyawaki, Ritsuro, Hatert, Frédéric, Pasero, Marco, Mills, Stuart J. (2022) IMA Commission on New Minerals, Nomenclature and Classification (CNMNC) – Newsletter 69. European Journal of Mineralogy, 34 (5) 463-468 doi:10.5194/ejm-34-463-2022
Localities for Uranophane
Showing 1,086 localities.
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The Locality List
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- This locality has estimated coordinates.
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- 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.
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La Dorgissière Mine, Saint-Amand-sur-Sèvre, Bressuire, Deux-Sèvres, Nouvelle-Aquitaine, France