Carnotite
A valid IMA mineral species - grandfathered
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About Carnotite
Marie-Adolphe Carnot
Formula:
K2(UO2)2(VO4)2 · 3H2O
Colour:
Bright yellow, yellow, greenish yellow
Lustre:
Sub-Vitreous, Resinous, Waxy, Silky, Dull, Earthy
Hardness:
2
Specific Gravity:
4.70
Crystal System:
Monoclinic
Member of:
Name:
Named in 1899 by Charles Friedel and Édouard Cumenge in honor of Marie-Adolphe Carnot [January 27, 1839 Paris, France - June 20, 1920], French mining engineer and chemist, professor at École des Mines and, later Chief Engineer of Mines and Inspector General of Mines, becoming Dean of the Ecole Nationale des Mines in 1901-1907, when he retired. The unrelated mineral silicocarnotite is also named after him.
Carnotite Group.
A secondary mineral resulting from the alteration of Uraninite, Montroseite, or Davidite. Occurs in sandstones, especially in paleochannels, near fossil carbonaceous matter, in calcretes and near playas.
Chemically close to vandermeerscheite.
A secondary mineral resulting from the alteration of Uraninite, Montroseite, or Davidite. Occurs in sandstones, especially in paleochannels, near fossil carbonaceous matter, in calcretes and near playas.
Chemically close to vandermeerscheite.
Unique Identifiers
Mindat ID:
907
Long-form identifier:
mindat:1:1:907:0
IMA Classification of Carnotite
Approved, 'Grandfathered' (first described prior to 1959)
First published:
1899
Classification of Carnotite
4.HB.05
4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
H : V[5,6] Vanadates
B : Uranyl Sorovanodates
4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
H : V[5,6] Vanadates
B : Uranyl Sorovanodates
40.2a.28.1
40 : HYDRATED NORMAL PHOSPHATES,ARSENATES AND VANADATES
2a : AB2(XO4)2·xH2O, containing (UO2)2+
40 : HYDRATED NORMAL PHOSPHATES,ARSENATES AND VANADATES
2a : AB2(XO4)2·xH2O, containing (UO2)2+
21.4.4
21 : Vanadates (and vanadates with arsenate or phosphate)
4 : Vanadates of U, Mn, Fe or Ni
21 : Vanadates (and vanadates with arsenate or phosphate)
4 : Vanadates of U, Mn, Fe or Ni
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 |
|---|---|---|
| Cnt | IMA–CNMNC | Warr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43 |
| Cnt | The Canadian Mineralogist (2019) | The Canadian Mineralogist (2019) The Canadian Mineralogist list of symbols for rock- and ore-forming minerals (December 30, 2019). download |
Physical Properties of Carnotite
Sub-Vitreous, Resinous, Waxy, Silky, Dull, Earthy
Transparency:
Translucent
Comment:
Silky to waxy when crystalline
Colour:
Bright yellow, yellow, greenish yellow
Comment:
Easily stained when fine-grained
Streak:
Strontian-yellow
Hardness:
2 on Mohs scale
Tenacity:
Fragile
Cleavage:
Perfect
on {001}, perfect, micaceous
on {001}, perfect, micaceous
Fracture:
Micaceous
Density:
4.70 g/cm3 (Measured) 4.91 g/cm3 (Calculated)
Comment:
Earthy material lower in compactness
Optical Data of Carnotite
Type:
Biaxial (-)
RI values:
nα = 1.750 nβ = 1.925 nγ = 1.950
2V:
Measured: 43° to 60°, Calculated: 26° to 36°
Birefringence:
0.200
Max. Birefringence:
δ = 0.200
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.
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:
r < v
Optical Extinction:
Z^a ~14°; X=c, Y=b
Pleochroism:
Weak
Comments:
X = Nearly colourless to pale grayish yellow
Y = Z = Canary yellow, lemon-yellow
Y = Z = Canary yellow, lemon-yellow
Comments:
Indices of refraction increase as water content decreases.
Chemistry of Carnotite
Mindat Formula:
K2(UO2)2(VO4)2 · 3H2O
Element Weights:
Crystallography of Carnotite
Crystal System:
Monoclinic
Class (H-M):
2/m - Prismatic
Space Group:
P21/b
Setting:
P21/a
Cell Parameters:
a = 10.47 Å, b = 8.41 Å, c = 6.91 Å
β = 103.83°
β = 103.83°
Ratio:
a:b:c = 1.245 : 1 : 0.822
Unit Cell V:
590.80 ų (Calculated from Unit Cell)
Z:
2
Morphology:
Crystals rare, diamond-shaped, flattened {001} and rhomboidal {110}, also lath-like [010] with {100} and {110} or {120}; (110) ^ (110) ~78°; commonly as fine aggregates or powdery; disseminated, compact massive.
Twinning:
On {001} as both the composition and twin plane.
Comment:
Space group determined based on synthetic, anhydrous material.
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) |
|---|---|---|---|---|---|---|---|
| 0012038 | Carnotite | Sundberg I, Sillen L G (1949) On the crystal structure of KUO2VO4 (synthetic anhydrous carnotite) Arkiv for Kemi 1 337-351 | 1949 | synthetic | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 6.56 Å | (100) |
| 4.25 Å | (30) |
| 3.53 Å | (50) |
| 3.25 Å | (30) |
| 3.12 Å | (70) |
| 2.571 Å | (20) |
| 2.156 Å | (30) |
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 10a: Neoproterozoic oxygenation/terrestrial biosphere | <0.6 |
| 53 : Other minerals with taphonomic origins | <0.4 |
Geological Setting:
Colorado Plateau type uranium deposits, near playas.
Type Occurrence of Carnotite
General Appearance of Type Material:
Yellow powder and powdery masses
Place of Conservation of Type Material:
University of Colorado, Boulder, Colorado: #2218. Harvard University, Cambridge, Massachusetts, USA: #106253.
Geological Setting of Type Material:
Colorado Plateau sedimentary vanadium-uranium deposits
Synonyms of Carnotite
Other Language Names for Carnotite
Varieties of Carnotite
| Thallium-bearing Carnotite | Thallium-bearing variety of Carnotite. |
Relationship of Carnotite to other Species
Member of:
Other Members of Carnotite Group:
| Margaritasite | (Cs,K,H3O)2(UO2)2(VO4)2 · H2O | Mon. 2/m : P21/b |
| Metatyuyamunite | Ca(UO2)2(VO4)2 · 3H2O | Orth. mmm (2/m 2/m 2/m) |
| Metavanuralite | Al(UO2)2(VO4)2(OH) · 8H2O | Tric. |
| Sengierite | Cu2(UO2)2(VO4)2 · 6H2O | Mon. 2/m : P21/b |
| Strelkinite | Na2(UO2)2(VO4)2 · 6H2O | Orth. |
| Tyuyamunite | Ca(UO2)2(VO4)2 · 5-8H2O | Orth. mmm (2/m 2/m 2/m) : Pnna |
| Vanuralite | Al(UO2)2(V2O8)(OH) · 11H2O | Mon. 2/m |
Common Associates
Associated Minerals Based on Photo Data:
| 21 photos of Carnotite associated with Uraninite | UO2 |
| 18 photos of Carnotite associated with Weeksite | K2(UO2)2(Si5O13) · 4H2O |
| 17 photos of Carnotite associated with Chalcedony | SiO2 |
| 15 photos of Carnotite associated with Chrysocolla | Cu2-xAlx(H2-xSi2O5)(OH)4 · nH2O, x < 1 |
| 14 photos of Carnotite associated with Tyuyamunite | Ca(UO2)2(VO4)2 · 5-8H2O |
| 11 photos of Carnotite associated with Davidite-(La) | La(Y,U)Fe2(Ti,Fe,Cr,V)18(O,OH,F)38 |
| 9 photos of Carnotite associated with Malachite | Cu2(CO3)(OH)2 |
| 7 photos of Carnotite associated with Chalcopyrite | CuFeS2 |
| 7 photos of Carnotite associated with Zippeite | K3(UO2)4(SO4)2O3(OH) · 3H2O |
| 5 photos of Carnotite associated with Quartz | SiO2 |
Related Minerals - Strunz-mindat Grouping
| 4.HB.05 | Margaritasite | (Cs,K,H3O)2(UO2)2(VO4)2 · H2O |
| 4.HB.10 | Sengierite | Cu2(UO2)2(VO4)2 · 6H2O |
| 4.HB.15 | Francevillite | Ba(UO2)2(VO4)2 · 5H2O |
| 4.HB.15 | Fritzscheite | Mn(UO2)2(PO4,VO4)2 · 10H2O (?) |
| 4.HB.15 | Curienite | Pb(UO2)2(VO4)2 · 5H2O |
| 4.HB.15 | Finchite | Sr(UO2)2(V2O8) · 5H2O |
| 4.HB.20 | Vanuralite | Al(UO2)2(V2O8)(OH) · 11H2O |
| 4.HB.20 | Metavanuralite | Al(UO2)2(VO4)2(OH) · 8H2O |
| 4.HB.25 | Metatyuyamunite | Ca(UO2)2(VO4)2 · 3H2O |
| 4.HB.25 | Tyuyamunite | Ca(UO2)2(VO4)2 · 5-8H2O |
| 4.HB.30 | Strelkinite | Na2(UO2)2(VO4)2 · 6H2O |
| 4.HB.35 | Uvanite | U6+2V5+6O21 · 15H2O (?) |
| 4.HB.40 | Rauvite | Ca(UO2)2(V10O28) · 16H2O |
| 4.HB.45 | Vandermeerscheite | K2[(UO2)2V2O8] · 2H2O |
Radioactivity
Radioactivity:
| Element | % Content | Activity (Bq/kg) | Radiation Type |
|---|---|---|---|
| Uranium (U) | 52.7677% | 13,191,925 | α, β, γ |
| Thorium (Th) | 0.0000% | 0 | α, β, γ |
| Potassium (K) | 8.6676% | 2,687 | 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 Carnotite
Not Fluorescent
Other Information
Notes:
Radioactive. Water content is partly zeolitic and varies with humidity at ambient temperatures. Readily soluble in acids.
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.
Industrial Uses:
Uranium ore
Internet Links for Carnotite
mindat.org URL:
https://www.mindat.org/min-907.html
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References for Carnotite
Reference List:
Crook, T., Blake, G. S. (1910) On Carnotite and an associated mineral complex from South Australia. Mineralogical Magazine and Journal of the Mineralogical Society, 15 (71) 271-284 doi:10.1180/minmag.1910.015.71.02
Larsen, Esper S. (1921) The microscopic determination of the nonopaque minerals. Bulletin 679. US Geological Survey doi:10.3133/b679 p.52
Murata, K. J., Cisney, E.A., Stieff, L. R., Zworykin, E.V. (1949) Synthesis, Base Exchange, and Photosensitivity of Carnotite, Tyuyamunite, and Related Minerals. Trace Elements Investigations 107. US Geological Survey doi:10.3133/tei107
Frondel, Clifford (1958) Systematic mineralogy of uranium and thorium. Bulletin 1064. US Geological Survey doi:10.3133/b1064 pp.243-247
Barton, Paul B. (1958) Synthesis and properties of carnotite and its alkali analogues. American Mineralogist, 43 (9-10) 799-817
Appleman, Daniel E., Evans, Howard T. (1965) The crystal structures of synthetic anhydrous carnotite, K2(UO2)2V2O8, and its cesium analogue, Cs2(UO2)2V2O8. American Mineralogist, 50 (7-8) 825-842
Localities for Carnotite
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.
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Monument Valley Mining District, USA