Astrocyanite-(Ce)
A valid IMA mineral species
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About Astrocyanite-(Ce)
Formula:
Cu2(Ce,Nd,La)2(UO2)(CO3)5(OH)2 · 1.5H2O
Colour:
Bright blue
Lustre:
Vitreous, Earthy
Hardness:
2 - 3
Specific Gravity:
3.80
Crystal System:
Hexagonal
Name:
From the Greek άστρον ("astron") for "star", κυανός ("kyanos") for "blue", in allusion to its colour and habit of the aggregates, and the dominant lanthanide element in its composition.
Type Locality:
Unique combination of elements.
Unique Identifiers
Mindat ID:
404
Long-form identifier:
mindat:1:1:404:8
IMA Classification of Astrocyanite-(Ce)
Approved
IMA Formula:
Cu2+2Ce3+2(U6+O2)(CO3)5(OH)2·1.5H2O
Approval year:
1989
First published:
1990
Classification of Astrocyanite-(Ce)
5.EF.05
5 : CARBONATES (NITRATES)
E : Uranyl Carbonates
F : UO2:CO3 = 1:5
5 : CARBONATES (NITRATES)
E : Uranyl Carbonates
F : UO2:CO3 = 1:5
16b.1.6.1
16b : HYDRATED CARBONATES CONTAINING HYDROXYL OR HALOGEN
1 : AmBn(XO3)pZqxH2O & with (m+n):p = 1:1
16b : HYDRATED CARBONATES CONTAINING HYDROXYL OR HALOGEN
1 : AmBn(XO3)pZq
11.11.17
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 |
|---|---|---|
| Acy-Ce | 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 Astrocyanite-(Ce)
Vitreous, Earthy
Transparency:
Translucent, Opaque
Colour:
Bright blue
Streak:
White, blue (bluish)
Hardness:
2 - 3 on Mohs scale
Density:
3.80 g/cm3 (Measured) 3.95 g/cm3 (Calculated)
Optical Data of Astrocyanite-(Ce)
Type:
Uniaxial (-)
RI values:
nω = 1.688 nε = 1.638
Max. Birefringence:
δ = 0.050
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 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:
Strong
Comments:
Strongly pleochroic from bright blue to pale blue, almost colorless.
Chemistry of Astrocyanite-(Ce)
Mindat Formula:
Cu2(Ce,Nd,La)2(UO2)(CO3)5(OH)2 · 1.5H2O
Element Weights:
Crystallography of Astrocyanite-(Ce)
Crystal System:
Hexagonal
Cell Parameters:
a = 14.96 Å, c = 26.86 Å
Ratio:
a:c = 1 : 1.795
Unit Cell V:
5,205.95 ų (Calculated from Unit Cell)
Z:
12
Morphology:
Platy {001}
Comment:
space group P6/mmm, P6mm, P622, P62m or P6m2
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 13.3 Å | (40) |
| 6.73 Å | (100) |
| 4.30 Å | (50) |
| 4.16 Å | (60) |
| 3.72 Å | (90) |
| 2.488 Å | (40) |
| 2.154 Å | (40) |
| 2.071 Å | (40) |
Reference:
Comments:
114.6-mm Debye-Scherrer camera, copper Ka radiation
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 Astrocyanite-(Ce)
General Appearance of Type Material:
Delicate rostettes of tablets.
Place of Conservation of Type Material:
Institut royal des Sciences naturalles de Belgique, Brussels, Belgium.
Geological Setting of Type Material:
Oxidation product of uraninite.
Associated Minerals at Type Locality:
Synonyms of Astrocyanite-(Ce)
Other Language Names for Astrocyanite-(Ce)
Common Associates
Associations Based on Photo Data:
| 15 photos of Astrocyanite-(Ce) associated with Kamotoite-(Y) | Y2(UO2)4(CO3)3O4 · 14H2O |
| 4 photos of Astrocyanite-(Ce) associated with Shabaite-(Nd) | Nd2Ca[(UO2)(CO3)3](CO3)2(H2O)10.5 |
| 4 photos of Astrocyanite-(Ce) associated with Uranophane | Ca(UO2)2(SiO3OH)2 · 5H2O |
| 3 photos of Astrocyanite-(Ce) associated with Uraninite | UO2 |
| 1 photo of Astrocyanite-(Ce) associated with Pendevilleite-(Y) | Mg2Y3Al(UO2)2(CO3)7(OH)6(H2O)16 |
Radioactivity
Radioactivity:
| Element | % Content | Activity (Bq/kg) | Radiation Type |
|---|---|---|---|
| Uranium (U) | 22.9219% | 5,730,475 | 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
Other Information
Notes:
Soluble with effervescence in dilute HCl.
Special Storage/
Display Requirements:
Display Requirements:
Radioactive
Health Risks:
This radioactive species sit always on massive uraninite and should be manipulated and stored with precautions.
Internet Links for Astrocyanite-(Ce)
mindat.org URL:
https://www.mindat.org/min-404.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 Astrocyanite-(Ce)
Reference List:
Deliens, Michel, Piret, Paul (1990) L'astrocyanite-(Ce), Cu2(TR)2(UO2)(CO3)5(OH)2.1,5 H2O, nouvelle espèce minérale de Kamoto, Shaba, Zaire. European Journal of Mineralogy, 2 (3) 407-412 doi:10.1127/0009.407
Localities for Astrocyanite-(Ce)
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.
DR Congo (TL) | |
| European Journal of Mineralogy (1990) +4 other references |
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Kamoto East Open cut, Kamoto, Mutshatsha, Lualaba, DR Congo