Margaritasite
A valid IMA mineral species
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About Margaritasite
Formula:
(Cs,K,H3O)2(UO2)2(VO4)2 · H2O
Colour:
Yellow
Specific Gravity:
5.41 (Calculated)
Crystal System:
Monoclinic
Member of:
Name:
Named for the Margaritas deposit, Mexico, the type locality.
Unique combination of elements. The only known Cs vanadate mineral. Also the sixth non-silicate oxysalt mineral with species-defining Cs, after borates londonite and ramanite-(Cs), cesiodymite (sulphate), caesiumpharmacosiderite (arsenate), and mccrillisite (phosphate).
A synergetic use of high-resolution XRD, SEM, EDX, SAED, and XAS shows that this natural margaritasite–carnotite consists of a mixture of practically pure margaritasite and a solid solution of margaritasite–carnotite, with variable amounts of cesium.
A synergetic use of high-resolution XRD, SEM, EDX, SAED, and XAS shows that this natural margaritasite–carnotite consists of a mixture of practically pure margaritasite and a solid solution of margaritasite–carnotite, with variable amounts of cesium.
Unique Identifiers
Mindat ID:
2572
Long-form identifier:
mindat:1:1:2572:6
Classification of Margaritasite
Francevillite sheet topology
The sheet topology found in minerals of the carnotite group.
IMA Classification of Margaritasite
Approved
IMA Formula:
Cs2(U6+O2)2(V5+O4)2·H2O
Approval year:
1980
First published:
1982
Type description reference:
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.28.2
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+
21.4.5
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.
| Symbol | Source | Reference for Standard |
|---|---|---|
| Mgt | 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 Margaritasite
Transparency:
Translucent
Colour:
Yellow
Density:
5.41 g/cm3 (Calculated)
Optical Data of Margaritasite
Type:
Biaxial (-)
Comments:
α:<1.83 γ:>2.70 Synthetic
Chemistry of Margaritasite
Mindat Formula:
(Cs,K,H3O)2(UO2)2(VO4)2 · H2O
Element Weights:
Crystallography of Margaritasite
Crystal System:
Monoclinic
Class (H-M):
2/m - Prismatic
Space Group:
P21/b
Setting:
P21/a
Cell Parameters:
a = 10.514(3) Å, b = 8.425(3) Å, c = 7.252(5) Å
β = 106.01°
β = 106.01°
Ratio:
a:b:c = 1.248 : 1 : 0.861
Unit Cell V:
617.47 ų (Calculated from Unit Cell)
Z:
2
Morphology:
Tabular crystals to 3 microns, massive.
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) |
|---|---|---|---|---|---|---|---|
| 0000135 | Margaritasite | Appleman D E, Evans H T (1965) The crystal structures of synthetic anhydrous carnotite, K2(UO2)2V2O8, and its cesium analogue, Cs2(UO2)2V2O8 American Mineralogist 50 825-842 |  | 1965 | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 6.965 Å | (100) |
| 3.600 Å | (70) |
| 3.344 Å | (70) |
| 3.489 Å | (60) |
| 3.231 Å | (50) |
| 3.164 Å | (50) |
| 3.129 Å | (35) |
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Stage 3b: Earth’s earliest hydrosphere | >4.45 |
| 16 : Low-? aqueous alteration of Hadean subaerial lithologies (see also #23) |
Type Occurrence of Margaritasite
Co-Type Localities:
General Appearance of Type Material:
Fine-grained yellow aggregates up to 1 mm. Individual crystals are 1 to 3 µm in size.
Place of Conservation of Type Material:
National Museum of Natural History (Smithsonian), Washington, D.C., USA, 149090.
Geological Setting of Type Material:
Fumarole deposits in rhyolite.
Associated Minerals at Type Locality:
Synonyms of Margaritasite
Other Language Names for Margaritasite
Relationship of Margaritasite to other Species
Member of:
Other Members of Carnotite Group:
| Carnotite | K2(UO2)2(VO4)2 · 3H2O | Mon. 2/m : P21/b |
| Metatyuyamunite | Ca(UO2)2(VO4)2 · 3H2O | Orth. mmm(2/m2/m2/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/m2/m2/m) : Pnna |
| Vanuralite | Al(UO2)2(V2O8)(OH) · 11H2O | Mon. 2/m |
Common Associates
Associations Based on Photo Data:
| 3 photos of Margaritasite associated with 'Rhyolite' | |
| 2 photos of Margaritasite associated with Haiweeite | Ca(UO2)2[Si5O12(OH)2] · 6H2O |
| 1 photo of Margaritasite associated with Quartz | SiO2 |
| 1 photo of Margaritasite associated with Sklodowskite | Mg(UO2)2(SiO3OH)2 · 6H2O |
Related Minerals - Strunz-mindat Grouping
| 4.HB.X | Spanoite | Tl2[(UO2)2(V2O8)] |
| 4.HB.05 | Carnotite | K2(UO2)2(VO4)2 · 3H2O |
| 4.HB.10 | Sengierite | Cu2(UO2)2(VO4)2 · 6H2O |
| 4.HB.15 | Francevillite | Ba(UO2)2(VO4)2 · 5H2O |
| 4.HB.15 | Fritzscheite | Mn2+(UO2)2(VO4,PO4)2 · 4H2O |
| 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) | 45.1771% | 11,294,275 | 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 Margaritasite
Not fluorescent
Other Information
Notes:
Radioactive.
Health Risks:
Radioactive
Internet Links for Margaritasite
mindat.org URL:
https://www.mindat.org/min-2572.html
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References for Margaritasite
Reference List:
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
Faudoa-Gómez, Fabián G., Fuentes-Cobas, Luis E., Esparza-Ponce, Hilda E., Canche-Tello, Jesús G., Reyes-Cortés, Ignacio A., Fuentes-Montero, Maria E., Eichert, Diane M., Rodríguez-Guerra, Yair, Montero-Cabrera, Maria-Elena (2024) Geological and Crystallochemical Characterization of the Margaritasite–Carnotite Mineral from the Uranium Region of Peña Blanca, Chihuahua, Mexico. Minerals, 14 (4). 431 doi:10.3390/min14040431
Localities for Margaritasite
Showing 2 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.
Mexico (TL) | |
| Wenrich et al. (1982) +2 other references |
| Wenrich et al. (1982) +1 other reference |
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Margaritas No. 1 Mine, Sierra Peña Blanca, Peña Blanca District, Aldama Municipality, Chihuahua, Mexico