Ježekite
A valid IMA mineral species
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About Ježekite
Bohuslav Ježek
Formula:
Na8[(UO2)(CO3)3](SO4)2 · 3H2O
Colour:
Light yellow to sulfuric yellow
Lustre:
Vitreous, Pearly
Hardness:
2
Specific Gravity:
2.966 (Calculated)
Crystal System:
Hexagonal
Name:
Named after Prof. Bohuslav Ježek (20 November 1877, Ústí nad Orlicí, Czech Republic - 10 January 1950, Písek, Czech Republic) a prominent Czech mineralogist and crystallographer at the Mining University in Ostrava and Pribram.
Not to be confused with Ježekite (of Slavik)
A supergene, low-temperature mineral formed by hydration-oxidation weathering of uraninite associated with post-mining processes.
A supergene, low-temperature mineral formed by hydration-oxidation weathering of uraninite associated with post-mining processes.
Name Encoding
Latin-1:
Jezekite
ASCII-7:
Jezekite
Unique Identifiers
Mindat ID:
46526
Long-form identifier:
mindat:1:1:46526:7
Similar Names
| Ježekite (of Slavik) | A synonym of Morinite |
IMA Classification of Ježekite
Approved
IMA Formula:
Na8(U6+O2)(CO3)3(S6+O4)2·3H2O
Approval year:
2014
First published:
2015
Classification of Ježekite
5.EG.15
5 : CARBONATES (NITRATES)
E : Uranyl Carbonates
G : With SO4 or SiO4
5 : CARBONATES (NITRATES)
E : Uranyl Carbonates
G : With SO4 or SiO4
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 |
|---|---|---|
| Jež | 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 Ježekite
Vitreous, Pearly
Transparency:
Transparent
Colour:
Light yellow to sulfuric yellow
Streak:
Very pale yellow
Hardness:
2 on Mohs scale
Comment:
~2
Tenacity:
Brittle
Cleavage:
Perfect
on {001} and along [010].
on {001} and along [010].
Fracture:
Irregular/Uneven
Density:
2.966 g/cm3 (Calculated)
Optical Data of Ježekite
Type:
Uniaxial (+)
RI values:
nω = 1.484(2) nε = 1.547(2)
Max. Birefringence:
δ = 0.063
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:
Moderate (negative)
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:
Non-pleochroic
Chemistry of Ježekite
Mindat Formula:
Na8[(UO2)(CO3)3](SO4)2 · 3H2O
Element Weights:
Crystallography of Ježekite
Crystal System:
Hexagonal
Class (H-M):
6m2 - Ditrigonal Dipyramidal
Space Group:
P62m
Setting:
P62m
Cell Parameters:
a = 9.0664(11) Å, c = 6.9110(6) Å
Ratio:
a:c = 1 : 0.762
Unit Cell V:
491.97 ų
Z:
1
Morphology:
Thin, bladed prismatic crystals, elongated along [001]. Crystals exhibit the forms {001}, {1-11}, {100} and {010}.
Twinning:
Commonly forming twins/intergrowths with a twin plane parallel to [001].
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 7.861 Å | (59) |
| 6.925 Å | (20) |
| 5.193 Å | (100) |
| 4.534 Å | (44) |
| 3.415 Å | (23) |
| 2.751 Å | (17) |
| 2.728 Å | (20) |
| 2.618 Å | (25) |
Locality:
Reference:
Comments:
From Type Description.
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Stage 7: Great Oxidation Event | <2.4 |
| 47a : [Near-surface hydration of prior minerals] | |
| 47b : [Sulfates and sulfites] | |
| 47c : [Carbonates, phosphates, borates, nitrates] | |
| 47f : [Uranyl (U⁶⁺) minerals] | |
| Stage 10b: Anthropogenic minerals | <10 Ka |
| 55 : Anthropogenic mine minerals |
Type Occurrence of Ježekite
General Appearance of Type Material:
As a crystalline crust composed of thin, bladed prismatic crystals of yellow to sulfuric yellow color on a gangue
Place of Conservation of Type Material:
Type material is deposited in the collections of the Fersman Mineralogical Museum of the Russian Academy of Sciences, Moscow, Russia, registration number 4606/1
Associated Minerals at Type Locality:
Synonyms of Ježekite
Other Language Names for Ježekite
Related Minerals - Strunz-mindat Grouping
| 5.EG.05 | Schröckingerite | NaCa3(UO2)(CO3)3(SO4)F · 10H2O |
| 5.EG.05 | 'UM1997-27-CO:CaHKSU' | KCa3(UO2)(CO3)3(SO4)F · 10H2O |
| 5.EG.10 | Lepersonnite-(Gd) | Ca(Gd,Dy)2(UO2)24(SiO4)4(CO3)8(OH)24 · 48H2O |
| 5.EG.10 | Lepersonnite-(Nd) | Nd4(UO2)24(SiO4)4(CO3)8(OH)28 · 48H2O |
Radioactivity
Radioactivity:
| Element | % Content | Activity (Bq/kg) | Radiation Type |
|---|---|---|---|
| Uranium (U) | 27.0443% | 6,761,075 | 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 Ježekite
Bright greenish white fluorescence under both long-wave and short-wave UV
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 Ježekite
mindat.org URL:
https://www.mindat.org/min-46526.html
Please feel free to link to this page.
Please feel free to link to this page.
Search Engines:
External Links:
Mineral Dealers:
References for Ježekite
Reference List:
Slavik, F. (1914) Sur les fluophosphates ternaires de Al2O3, RO et R2O (morinite, ježekite, lacroixite). Bulletin de la Société française de Minéralogie, 37 (5). 152-162 doi:10.3406/bulmi.1914.3588
Williams, P. A., Hatert, F., Pasero, M., Mills, S. J. (2015) New minerals and nomenclature modifications approved in 2014 and 2015. Newsletter No 23. Mineralogical Magazine, 79 (1) 51-58 doi:10.1180/minmag.2015.079.1.05
Localities for Ježekite
Showing 1 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 (TL) | |
| Williams et al. (2015) +1 other reference |
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Geschieber vein, Svornost Mine, Jáchymov, Karlovy Vary District, Karlovy Vary Region, Czech Republic