Rameauite
A valid IMA mineral species
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About Rameauite
Jacques Rameau
Formula:
K2Ca(UO2)6O6(OH)4 · 6H2O
Colour:
Orange
Specific Gravity:
5.60
Crystal System:
Monoclinic
Name:
Named after Jacques Rameau (1926-1960), French prospector with the Commissariat à l'Energie Atomique, who discovered the deposit where the mineral was found.
Recent structure refinement shows that it is based on sheets with the β-U3O8 topology, and there are UO6 and UO7 bipyramids; similar sheets are found in spriggite, ianthinite, and wyartite. Adjacent sheets in rameauite are linked via K–O, Ca–O and H bonds. The interlayer space hosts K, Ca and water. The interstitial cations are linked to form infinite chains extending along [101].
Pseudo-tetragonal due to cell twinning.
Pseudo-tetragonal due to cell twinning.
Unique Identifiers
Mindat ID:
3356
Long-form identifier:
mindat:1:1:3356:1
Similar Names
| Roméite | A solid-solution series between two end-member minerals |
IMA Classification of Rameauite
Approved
IMA Formula:
K2Ca(U6+O2)6O6(OH)4·6H2O
Approval year:
1971
First published:
1972
Classification of Rameauite
4.GB.05
4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
G : Uranyl Hydroxides
B : With additional cations (K, Ca, Ba, Pb, etc.); with mainly UO2(O,OH)5 pentagonal polyhedra
4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
G : Uranyl Hydroxides
B : With additional cations (K, Ca, Ba, Pb, etc.); with mainly UO2(O,OH)5 pentagonal polyhedra
5.5.2.1
5 : OXIDES CONTAINING URANIUM OR THORIUM
5 : AX3O10·xH2O
5 : OXIDES CONTAINING URANIUM OR THORIUM
5 : AX3O10·xH2O
7.16.12
7 : Oxides and Hydroxides
16 : Oxides of U
7 : Oxides and Hydroxides
16 : Oxides 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 |
|---|---|---|
| Rme | 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 Rameauite
Colour:
Orange
Cleavage:
Distinct/Good
On {010}.
On {010}.
Density:
5.60 g/cm3 (Measured) 5.467 g/cm3 (Calculated)
Optical Data of Rameauite
Type:
Biaxial (-)
Dispersion:
relatively weak
Optical Extinction:
X = b; Z ∧ c = 4°–6°.
Reflectivity:
| Wavelength | R1 (%) | R2 (%) |
|---|---|---|
| 400nm | 14.1% | 15.2% |
| 420nm | 11.9% | 12.4% |
| 440nm | 11.1% | 11.5% |
| 460nm | 10.9% | 11.2% |
| 480nm | 10.6% | 10.9% |
| 500nm | 10.4% | 10.7% |
| 520nm | 10.5% | 10.7% |
| 540nm | 10.7% | 10.9% |
| 560nm | 10.6% | 10.8% |
| 580nm | 10.4% | 10.6% |
| 600nm | 10.3% | 10.5% |
| 620nm | 10.2% | 10.4% |
| 640nm | 10.2% | 10.3% |
| 660nm | 10.0% | 10.1% |
| 680nm | 10.0% | 10.1% |
| 700nm | 9.9% | 10.0% |
Graph shows reflectance levels at different wavelengths (in nm). Peak reflectance is 15.2%.
R1 shown in black, R2 shown in red
Comments:
Reflectivity on face {010}.
Chemistry of Rameauite
Mindat Formula:
K2Ca(UO2)6O6(OH)4 · 6H2O
Element Weights:
Crystallography of Rameauite
Crystal System:
Monoclinic
Class (H-M):
m - Domatic
Space Group:
Bb
Setting:
Cc
Cell Parameters:
a = 13.947(3) Å, b = 14.300(3) Å, c = 13.888(3) Å
β = 118.50(3)°
β = 118.50(3)°
Ratio:
a:b:c = 0.975 : 1 : 0.971
Unit Cell V:
2,434.19 ų (Calculated from Unit Cell)
Z:
2
Morphology:
Twinned on {100}, slightly flattened parallel to {010}, elongated parallel to [001], with a pseudo-hexagonal section. Forms include {010}, {100}, {001}, and {110}.
Twinning:
Type material always twinned on {100}.
Comment:
As in agrinierite, cell twinning occurs due to a mirror in (101), i.e., due to reticular merohedry (diffraction type II); the supercell is pseudo-tetragonal
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 7.12 Å | (very very strong) |
| 3.495 Å | (very very strong) |
| 3.139 Å | (very very strong) |
| 3.124 Å | (very very strong) |
| 3.566 Å | (very strong) |
| 3.473 Å | (very strong) |
| 3.185 Å | (very strong) |
Comments:
Margnac mine, France. Data from the 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] | |
| 47f : [Uranyl (U⁶⁺) minerals] |
Type Occurrence of Rameauite
General Appearance of Type Material:
Small (up to 1 mm long) orange crystals, twinned.
Place of Conservation of Type Material:
University of Pierre and Marie Curie, Paris, France.
National School of Mines, Paris, France.
National Museum of Natural History, Washington, D.C., USA, 137454.
National School of Mines, Paris, France.
National Museum of Natural History, Washington, D.C., USA, 137454.
Geological Setting of Type Material:
Oxidized zone of a uranium deposit.
Associated Minerals at Type Locality:
Synonyms of Rameauite
Other Language Names for Rameauite
Common Associates
Associations Based on Photo Data:
| 2 photos of Rameauite associated with Urancalcarite | Ca(UO2)3(CO3)(OH)6 · 3H2O |
| 2 photos of Rameauite associated with Uranophane | Ca(UO2)2(SiO3OH)2 · 5H2O |
| 1 photo of Rameauite associated with Uraninite | UO2 |
| 1 photo of Rameauite associated with Schoepite | (UO2)8O2(OH)12 · 12H2O |
Related Minerals - Strunz-mindat Grouping
| 4.GB.05 | Agrinierite | K2(Ca,Sr)[(UO2)3O3(OH)2]2 · 5H2O |
| 4.GB.05 | Compreignacite | K2(UO2)6O4(OH)6 · 7H2O |
| 4.GB.10 | Becquerelite | Ca(UO2)6O4(OH)6 · 8H2O |
| 4.GB.10 | Billietite | Ba(UO2)6O4(OH)6 · 4-8H2O |
| 4.GB.10 | Protasite | Ba(UO2)3O3(OH)2 · 3H2O |
| 4.GB.15 | Richetite | (Fe3+,Mg)Pb 8.6(UO2)36O36(OH)24 · 41H2O |
| 4.GB.20 | Calciouranoite | (Ca,Ba,Pb)U2O7 · 5H2O |
| 4.GB.20 | Bauranoite | Ba(UO2)2(OH)6 · 1-2H2O |
| 4.GB.20 | Metacalciouranoite | (Ca,Ba,Pb,K2)U2O7 · 2H2O |
| 4.GB.25 | Fourmarierite | Pb(UO2)4O3(OH)4 · 4H2O |
| 4.GB.30 | Wölsendorfite | Pb7(UO2)14O19(OH)4 · 12H2O |
| 4.GB.35 | Masuyite | Pb(UO2)3O3(OH)2 · 3H2O |
| 4.GB.40 | Vandendriesscheite | PbU7O22 · 12H2O |
| 4.GB.40 | Metavandendriesscheite | PbU7O22 · nH2O n < 12 |
| 4.GB.45 | Vandenbrandeite | Cu(UO2)(OH)4 |
| 4.GB.50 | Sayrite | Pb2(UO2)5O6(OH)2 · 4H2O |
| 4.GB.55 | Curite | Pb3(H2O)2[(UO2)4O4(OH)3]2 |
| 4.GB.60 | Iriginite | (UO2)Mo2O7 · 3H2O |
| 4.GB.65 | Uranosphaerite | Bi(UO2)O2(OH) |
| 4.GB.70 | Holfertite | CaxU6+2-xTi(O8-xOH4x) · 3H2O |
| 4.GB.75 | Carlosbarbosaite | (UO2)2Nb2O6(OH)2 · 2H2O |
| 4.GB.80 | Gauthierite | KPb[(UO2)7O5(OH)7] · 8H2O |
| 4.GB.85 | Kroupaite | KPb0.5[(UO2)8O4(OH)10] · 10H2O |
| 4.GB.90 | Leesite | K(H2O)2[(UO2)4O2(OH)5] · 3H2O |
| 4.GB.95 | Shinkolobweite | Pb1.333[U5+O(OH)(UO2)5O4.67(OH)5.33](H2O)5 |
| 4.GB.95 | Nollmotzite | Mg[U5+(U6+O2)2O4F3] · 4H2O |
Radioactivity
Radioactivity:
| Element | % Content | Activity (Bq/kg) | Radiation Type |
|---|---|---|---|
| Uranium (U) | 71.0337% | 17,758,425 | α, β, γ |
| Thorium (Th) | 0.0000% | 0 | α, β, γ |
| Potassium (K) | 3.8893% | 1,206 | 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 Rameauite
mindat.org URL:
https://www.mindat.org/min-3356.html
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References for Rameauite
Reference List:
Cesbron, F., Brown, W. L., Bariand, P., Geffroy, J. (1972) Rameauite and agrinierite, two new hydrated complex uranyl oxides from Margnac, France. Mineralogical Magazine, 38 (299) 781-789 doi:10.1180/minmag.1972.038.299.01
Plášil, Jakub, Škoda, Radek, Čejka, Jiří, Bourgoin, Vincent, Boulliard, Jean-Claude (2016) Crystal structure of the uranyl-oxide mineral rameauite. European Journal of Mineralogy, 28 (5) 959-967 doi:10.1127/ejm/2016/0028-2568
Plášil, Jakub; Petříček, Václav; Škoda, Radek; Meisser, Nicolas; Kasatkin, Anatoly V. (2021) Hidden and apparent twins in uranyl-oxide minerals agrinierite and rameauite: a demonstration of metric and reticular merohedry. Journal of Applied Crystallography, 54 (6). 1656-1663 doi:10.1107/s1600576721009663
Localities for Rameauite
Showing 9 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 | |
| King (n.d.) |
France | |
| Queneau (n.d.) |
| Cesbron et al. (1972) |
Nigeria | |
| Tsang et al. (2018) |
Switzerland | |
| Meisser (2012) |
| Meisser (2012) |
USA | |
| Anthony et al. (1995) +1 other reference |
| Castor et al. (2004) |
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Rhyolite Ridge Li-B Deposit, Esmeralda County, Nevada, USA