Grimselite
A valid IMA mineral species
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About Grimselite
Formula:
K3Na(UO2)(CO3)3 · H2O
Colour:
Yellow
Lustre:
Vitreous
Hardness:
2 - 2½
Specific Gravity:
3.30
Crystal System:
Hexagonal
Name:
For the Grimsel area, in which the type locality is situated.
This page provides mineralogical data about Grimselite.
Unique Identifiers
Mindat ID:
1751
Long-form identifier:
mindat:1:1:1751:6
IMA Classification of Grimselite
Approved
IMA Formula:
K3Na(U6+O2)(CO3)3·H2O
Approval year:
1971
First published:
1972
Type description reference:
Classification of Grimselite
5.ED.35
5 : CARBONATES (NITRATES)
E : Uranyl Carbonates
D : UO2:CO3 = 1:3
5 : CARBONATES (NITRATES)
E : Uranyl Carbonates
D : UO2:CO3 = 1:3
15.2.6.1
15 : HYDRATED NORMAL CARBONATES
2 : AmBn(XO3)p·xH2O, with (m+n):p > 1:1
15 : HYDRATED NORMAL CARBONATES
2 : AmBn(XO3)p·xH2O, with (m+n):p > 1:1
11.11.4
11 : Carbonates
11 : Carbonates of Cr and U
11 : Carbonates
11 : Carbonates of Cr and 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 |
|---|---|---|
| Gsl | 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 Grimselite
Vitreous
Transparency:
Transparent, Translucent
Colour:
Yellow
Streak:
Pale yellow
Hardness:
2 - 2½ on Mohs scale
Tenacity:
Brittle
Fracture:
Conchoidal
Density:
3.30 g/cm3 (Measured) 3.27 g/cm3 (Calculated)
Comment:
Measured on synthetic material
Optical Data of Grimselite
Type:
Uniaxial (-)
RI values:
nω = 1.601(2) nε = 1.480(2)
Max. Birefringence:
δ = 0.121
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:
Low (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 uniaxial interference figure - the conoscopic
(convergent-light, Bertrand-lens-in) view, for a grain cut with the optic axis
centred and vertical. The coloured rings are isochromatics, computed with the
same physics as the Michel-Lévy bar above; the dark cross is the isogyre.
For a genuinely uniaxial mineral viewed this way, that cross stays perfectly stationary if you rotate the stage - unlike a biaxial mineral, where it splits apart on rotation. That invariance is itself the standard diagnostic test for telling uniaxial and biaxial minerals apart at the microscope.
For a genuinely uniaxial mineral viewed this way, that cross stays perfectly stationary if you rotate the stage - unlike a biaxial mineral, where it splits apart on rotation. That invariance is itself the standard diagnostic test for telling uniaxial and biaxial minerals apart at the microscope.
Pleochroism:
Visible
Comments:
Distinct; 0 == yellow; E== colorless.
Comments:
weakly biaxial (-).
Chemistry of Grimselite
Mindat Formula:
K3Na(UO2)(CO3)3 · H2O
Element Weights:
Crystallography of Grimselite
Crystal System:
Hexagonal
Class (H-M):
6m2 - Ditrigonal Dipyramidal
Space Group:
P62c
Cell Parameters:
a = 9.30(2) Å, c = 8.26(2) Å
Ratio:
a:c = 1 : 0.888
Unit Cell V:
618.69 ų (Calculated from Unit Cell)
Z:
2
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) |
|---|---|---|---|---|---|---|---|
| 0005731 | Grimselite | Li Y, Burns P C (2001) The crystal structure of synthetic grimselite, K3Na[(UO2)(CO3)3](H2O) The Canadian Mineralogist 39 1147-1151 |  | 2001 | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 5.76 Å | (10) |
| 8.09 Å | (8) |
| 3.08 Å | (8 |
| 0.985 Å | (8) |
| 3.65 Å | (7b) |
| 2.86 Å | (7) |
| 2.68 Å | (7) |
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Stage 7: Great Oxidation Event | <2.4 |
| 47a : [Near-surface hydration of prior minerals] | |
| 47c : [Carbonates, phosphates, borates, nitrates] | |
| 47f : [Uranyl (U⁶⁺) minerals] |
Type Occurrence of Grimselite
General Appearance of Type Material:
Prismatic hexagonal crystals
Place of Conservation of Type Material:
Institute for Mineralogy and Crystal Chemistry, University of Stuttgart, Stuttgart, Germany.
Geological Setting of Type Material:
Secondary mineral in veins in mineralized granodiorite.
Associated Minerals at Type Locality:
Reference:
Synonyms of Grimselite
Other Language Names for Grimselite
Common Associates
Related Minerals - Strunz-mindat Grouping
| 5.ED. | Szilagyiite | NaCa3(UO2)(CO3)3(SeO3)F(H2O)6 |
| 5.ED. | Pendevilleite-(Y) | Mg2Y3Al(UO2)2(CO3)7(OH)6(H2O)16 |
| 5.ED. | Paramarkeyite | Ca2(UO2)(CO3)3 · 5H2O |
| 5.ED.05 | Bayleyite | Mg2(UO2)(CO3)3 · 18H2O |
| 5.ED.10 | Swartzite | MgCa(UO2)(CO3)3 · 12H2O |
| 5.ED.15 | Albrechtschraufite | Ca4Mg(UO2)2(CO3)6F2 · 17-18H2O |
| 5.ED.20 | Liebigite | Ca2(UO2)(CO3)3 · 11H2O |
| 5.ED.25 | Rabbittite | Ca3Mg3(UO2)2(CO3)6(OH)4 · 18H2O |
| 5.ED.30 | Andersonite | Na2Ca(UO2)(CO3)3 · 5.33H2O |
| 5.ED.40 | Widenmannite | Pb2(OH)2[(UO2)(CO3)2] |
| 5.ED.45 | Znucalite | Zn10Ca0.83(UO2)0.83(CO3)4(OH)15.31(H2O)5.48 |
| 5.ED.50 | Agricolaite | K4(UO2)(CO3)3 |
| 5.ED.50 | Čejkaite | Na4(UO2)(CO3)3 |
| 5.ED.55 | Línekite | K2Ca3[(UO2)(CO3)3]2 · 8H2O |
| 5.ED.55 | Braunerite | K2Ca(UO2)(CO3)3 · 6H2O |
| 5.ED.60 | Leószilárdite | Na6Mg(UO2)2(CO3)6 · 6H2O |
| 5.ED.65 | Pseudomarkeyite | Ca8(UO2)4(CO3)12 · 21H2O |
| 5.ED.65 | Natromarkeyite | Na2Ca8(UO2)4(CO3)13 · 27H2O |
| 5.ED.65 | Markeyite | Ca9(UO2)4(CO3)13 · 28H2O |
| 5.ED.70 | Paddlewheelite | MgCa5Cu2(UO2)4(CO3)12(H2O)33 |
Radioactivity
Radioactivity:
| Element | % Content | Activity (Bq/kg) | Radiation Type |
|---|---|---|---|
| Uranium (U) | 39.1267% | 9,781,675 | α, β, γ |
| Thorium (Th) | 0.0000% | 0 | α, β, γ |
| Potassium (K) | 19.2807% | 5,977 | 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
Other Information
Notes:
Soluble in water
Health Risks:
Radioactive
Internet Links for Grimselite
mindat.org URL:
https://www.mindat.org/min-1751.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 Grimselite
Reference List:
Walenta, K. (1972) Grimselit, ein neues Kalium-Natrium-Uranylkarbonat aus dem Grimselgebiet (Oberhasli, Kt. Bern, Schweiz). Schweizerische Mineralogische und Petrographische Mitteilungen 52, 93-108.(Abs. in American Mineralogist (1973): 58: 139)
O'Brien, Timothy J., Williams, Peter A. (1983) The aqueous chemistry of uranium minerals. 4. Schröckingerite, grimselite, and related alkali uranyl carbonates. Mineralogical Magazine, 47 (342) 69-73 doi:10.1180/minmag.1983.047.342.12
Li, Y.; Burns, P. C. (2001) The crystal structure of synthetic grimselite, K3Na[(UO2)(CO3)3](H2O). The Canadian Mineralogist, 39 (4). p.1147-1151. doi:10.2113/gscanmin.39.4.1147
Kubatko, K.-A. (2005) Thermodynamics of uranyl minerals: Enthalpies of formation of rutherfordine, UO2CO3, andersonite, Na2CaUO2(CO3)3(H2O)5, and grimselite, K3NaUO2(CO3)3H2O. American Mineralogist, 90 (8) 1284-1290 doi:10.2138/am.2005.1821
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., Fejfarová, K., Skála, R., Škoda, R., Meisser, N., Hlousek, J., Císařová, I., Dušek, M., Veselovský, F., Čejka, J., Sejkora, J., Ondruš, P. (2012) The crystal chemistry of the uranyl carbonate mineral grimselite, (K, Na)3Na[(UO2)(CO3)3](H2O), from Jáchymov, Czech Republic. Mineralogical Magazine, 76 (3) 443-453 doi:10.1180/minmag.2012.076.3.01
Localities for Grimselite
Showing 5 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.
Czech Republic | |
| Tvrdý et al. (2010) |
| Pauliš P. et al. (Kutna Hora, issue 1) | |
| Plášil et al. (2017) | |
Switzerland (TL) | |
| Walenta (1972) |
| Laverov et al. (2008) |
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Rovnost Mine, Jáchymov, Karlovy Vary District, Karlovy Vary Region, Czech Republic