Swamboite-(Nd)
A valid IMA mineral species
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About Swamboite-(Nd)
Formula:
Nd0.333[(UO2)(SiO3OH)](H2O)~2.5
Colour:
Deep to very pale yellow
Hardness:
2½
Specific Gravity:
4.0
Crystal System:
Monoclinic
Name:
Named after its discovery locality, in the Swambo deposit, Democratic Republic of the Congo (Zaire). Renamed by IMA as Swamboite-(Nd) in 2017.
Type Locality:
Originally described as a new mineral with a formula U0.333H2(UO2SiO4)2·10H2O.
The correct formula is: Nd0.333[(UO2)(SiO3OH)](H2O)∼2.5; the formula and name were changed in 2017 (IMA 17-A redefinition/renaming proposal).
The correct formula is: Nd0.333[(UO2)(SiO3OH)](H2O)∼2.5; the formula and name were changed in 2017 (IMA 17-A redefinition/renaming proposal).
Unique Identifiers
Mindat ID:
3843
Long-form identifier:
mindat:1:1:3843:6
IMA Classification of Swamboite-(Nd)
Approved
IMA status notes:
Redefined by the IMA, Renamed by the IMA
IMA Formula:
Nd0.333[(U6+O2)(SiO3OH)](H2O)~2.5
Approval year:
1981
Approval history:
Redefined and renamed as Swamboite-(Nd) by IMA in febr. 2017 (Proposal 17-A)
Classification of Swamboite-(Nd)
9.AK.20
9 : SILICATES (Germanates)
A : Nesosilicates
K : Uranyl neso- and polysilicates
9 : SILICATES (Germanates)
A : Nesosilicates
K : Uranyl neso- and polysilicates
53.3.1.8
53 : NESOSILICATES Insular SiO4 Groups and Other Anions or Complex Cations
3 : Insular SiO4 Groups and Other Anions of Complex Cations with (UO2)
53 : NESOSILICATES Insular SiO4 Groups and Other Anions or Complex Cations
3 : Insular SiO4 Groups and Other Anions of Complex Cations with (UO2)
14.16.4
14 : Silicates not Containing Aluminum
16 : Silicates of U
14 : Silicates not Containing Aluminum
16 : Silicates of 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 |
|---|---|---|
| Swa-Nd | 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 Swamboite-(Nd)
Transparency:
Transparent
Colour:
Deep to very pale yellow
Hardness:
2½ on Mohs scale
Cleavage:
Distinct/Good
{201}, good.
{201}, good.
Density:
4.0 g/cm3 (Measured) 4.064 g/cm3 (Calculated)
Optical Data of Swamboite-(Nd)
Type:
Biaxial (-)
RI values:
nα = 1.640 nβ = 1.661 nγ = 1.663
2V:
Measured: 30° , Calculated: 32°
Max. Birefringence:
δ = 0.023
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:
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 biaxial acute bisectrix (Bxa) interference figure
- the conoscopic view for a grain cut perpendicular to the acute bisectrix, using
this mineral's 2V. The two small white dots mark the melatopes - the points
where the two optic axes emerge - and are shown only when they fall within the
field of view. The coloured bands are isochromatics, and the dark bands are
isogyres.
Rotate the stage: at 0°/90° the isogyres form a cross through the melatopes; at 45° they pull apart into curved hyperbolas. That splitting on rotation - absent in a uniaxial figure - is the standard diagnostic test for telling biaxial minerals from uniaxial ones. If 2V is large, the melatopes may fall outside the field of view, as they often do at the microscope too.
Rotate the stage: at 0°/90° the isogyres form a cross through the melatopes; at 45° they pull apart into curved hyperbolas. That splitting on rotation - absent in a uniaxial figure - is the standard diagnostic test for telling biaxial minerals from uniaxial ones. If 2V is large, the melatopes may fall outside the field of view, as they often do at the microscope too.
Dispersion:
r < v moderate
Pleochroism:
Visible
Comments:
X = colorless; Y = Z = light yellow
Chemistry of Swamboite-(Nd)
Mindat Formula:
Nd0.333[(UO2)(SiO3OH)](H2O)~2.5
Element Weights:
Crystallography of Swamboite-(Nd)
Crystal System:
Monoclinic
Class (H-M):
2/m - Prismatic
Space Group:
P21/b
Setting:
P21/a
Cell Parameters:
a = 17.64(3) Å, b = 21.00(5) Å, c = 20.12(4) Å
β = 103.42°
β = 103.42°
Ratio:
a:b:c = 0.84 : 1 : 0.958
Unit Cell V:
7,249.74 ų (Calculated from Unit Cell)
Z:
18
Morphology:
As acicular crystals elongated
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 8.67 Å | (100) |
| 4.75 Å | (80) |
| 4.32 Å | (80) |
| 3.51 Å | (60) |
| 2.979 Å | (60b) |
| 5.85 Å | (50) |
| 4.49 Å | (50) |
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Stage 7: Great Oxidation Event | <2.4 |
| 47a : [Near-surface hydration of prior minerals] | |
| 47f : [Uranyl (U⁶⁺) minerals] |
Type Occurrence of Swamboite-(Nd)
General Appearance of Type Material:
acicular crystals
Place of Conservation of Type Material:
Royal Museum of Central Africa, Tervuren, Belgium, RGM13690.
Associated Minerals at Type Locality:
Synonyms of Swamboite-(Nd)
Other Language Names for Swamboite-(Nd)
Common Associates
Associations Based on Photo Data:
| 24 photos of Swamboite-(Nd) associated with Soddyite | (UO2)2SiO4 · 2H2O |
| 5 photos of Swamboite-(Nd) associated with Heterogenite | Co3+O(OH) |
| 4 photos of Swamboite-(Nd) associated with Curite | Pb3(H2O)2[(UO2)4O4(OH)3]2 |
| 1 photo of Swamboite-(Nd) associated with Uranophane | Ca(UO2)2(SiO3OH)2 · 5H2O |
| 1 photo of Swamboite-(Nd) associated with Uraninite | UO2 |
| 1 photo of Swamboite-(Nd) associated with Gypsum | CaSO4 · 2H2O |
Related Minerals - Strunz-mindat Grouping
| 9.AK. | 'Orlite' | Pb3(UO2)3(Si2O7)2 · 6H2O |
| 9.AK.05 | Soddyite | (UO2)2SiO4 · 2H2O |
| 9.AK.10 | Sklodowskite | Mg(UO2)2(SiO3OH)2 · 6H2O |
| 9.AK.10 | Cuprosklodowskite | Cu(UO2)2(SiO3OH)2 · 6H2O |
| 9.AK.10 | Oursinite | Co(UO2)2(SiO3OH)2 · 6H2O |
| 9.AK.15 | Parauranophane | Ca(UO2)2(SiO3OH)2 · 5H2O |
| 9.AK.15 | Uranophane | Ca(UO2)2(SiO3OH)2 · 5H2O |
| 9.AK.15 | Natroboltwoodite | Na(UO2)(SiO3OH) · H2O |
| 9.AK.15 | Kasolite | Pb(UO2)(SiO4) · H2O |
| 9.AK.15 | Boltwoodite | (K,Na)(UO2)(SiO3OH) · 1.5H2O |
| 9.AK.25 | Haiweeite | Ca(UO2)2[Si5O12(OH)2] · 6H2O |
| 9.AK.25 | Metahaiweeite | Ca(UO2)2Si6O15 · nH2O |
| 9.AK.30 | Weeksite | K2(UO2)2(Si5O13) · 4H2O |
| 9.AK.30 | Coutinhoite | ThxBa(1-2x)(UO2)2Si5O13 · (H2O)1+y (0 < x < 0.5 and 0 < y < (2+x)) |
| 9.AK.30 | Barronite | (◻0.5Ba0.5)(UO2)2Si5O12(OH) · 2H2O |
| 9.AK.35 | Magnioursilite | Mg4(UO2)4(Si2O5)5(OH)6 · 20H2O |
| 9.AK.35 | Calcioursilite | Ca4(UO2)4(Si2O5)5(OH)6 · 15H2O |
| 9.AK.40 | Uranosilite | UO3 · 7SiO2 |
Radioactivity
Radioactivity:
| Element | % Content | Activity (Bq/kg) | Radiation Type |
|---|---|---|---|
| Uranium (U) | 59.6341% | 14,908,525 | 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
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 Swamboite-(Nd)
mindat.org URL:
https://www.mindat.org/min-3843.html
Please feel free to link to this page.
Please feel free to link to this page.
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External Links:
Mineral Dealers:
References for Swamboite-(Nd)
Reference List:
Deliens, M., Piret, P. (1981) La swamboïte, nouveau silicate d'uranium hydraté du shaba, Zaïre. The Canadian Mineralogist, 19 (4) 553-557
Hålenius, U., Hatert, F., Pasero, M., Mills, S. J. (2017) New minerals and nomenclature modifications approved in 2017. CNMNC Newsletter No 36. Mineralogical Magazine, 81 (2) 403-409 doi:10.1180/minmag.2017.081.022
Plášil, Jakub; Petříček, Václav; Locock, Andrew J.; Škoda, Radek; Burns, Peter C. (2017) The (3+3) commensurately modulated structure of the uranyl silicate mineral swamboite-(Nd), Nd0.333[(UO2)(SiO3OH)](H2O)2.41. Zeitschrift für Kristallographie - Crystalline Materials, 233 (3-4). 223-231 doi:10.1515/zkri-2017-2119
Localities for Swamboite-(Nd)
Showing 3 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.
Brazil | |
| Pires et al. (2014) |
DR Congo (TL) | |
| Deliens et al. (1981) +2 other references |
USA | |
| Haynes (2000) |
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Swambo Hill, Kambove Territory, Haut-Katanga, DR Congo