Masuyite
A valid IMA mineral species - grandfathered
This page is currently not sponsored. Click here to sponsor this page.
About Masuyite
Formula:
Pb(UO2)3O3(OH)2 · 3H2O
Colour:
Red-orange, orange, brownish orange.
Specific Gravity:
5.08
Crystal System:
Orthorhombic
Name:
After Gustave Masuy (born Brugge, Belgium, on February 9th 1905 and passed away in Brussels on June 9th 1945), Belgian geologist.
Might actually represent two different species (cf. Deliens & Piret, 1996). The crystal structure of masuyite was determined by Burns & Hanchar (1999).
Unique Identifiers
Mindat ID:
2589
Long-form identifier:
mindat:1:1:2589:4
IMA Classification of Masuyite
Approved, 'Grandfathered' (first described prior to 1959)
IMA Formula:
Pb2+(U6+O2)3O3(OH)2(H2O)3
First published:
1947
Classification of Masuyite
4.GB.35
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
5.2.2.1
5 : OXIDES CONTAINING URANIUM OR THORIUM
2 : AXO3·xH2O
5 : OXIDES CONTAINING URANIUM OR THORIUM
2 : AXO3·xH2O
7.16.27
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 |
|---|---|---|
| Msy | 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 Masuyite
Transparency:
Transparent
Colour:
Red-orange, orange, brownish orange.
Cleavage:
Perfect
{001}, perfect; {010}, good.
{001}, perfect; {010}, good.
Density:
5.08 g/cm3 (Measured)
Optical Data of Masuyite
Type:
Biaxial (-)
RI values:
nα = 1.785 nβ = 1.895 - 1.906 nγ = 1.915 - 1.917
2V:
Measured: 40° to 50°, Calculated: 44°
Max. Birefringence:
δ = 0.130 - 0.132
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 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:
extreme
Pleochroism:
Weak
Comments:
X = pale yellow; Y = Z = deep golden yellow
Chemistry of Masuyite
Mindat Formula:
Pb(UO2)3O3(OH)2 · 3H2O
Element Weights:
Elements listed:
Crystallography of Masuyite
Crystal System:
Orthorhombic
Class (H-M):
mmm(2/m2/m2/m) - Dipyramidal
Cell Parameters:
a = 13.98(10) Å, b = 12.17(27) Å, c = 14.56(36) Å
Ratio:
a:b:c = 1.149 : 1 : 1.196
Unit Cell V:
2,477.19 ų (Calculated from Unit Cell)
Z:
2
Twinning:
Very common on {110} or {130} as twin and composition planes, contact and repeated, individuals with parallel to {001}.
Comment:
Space Group: P cna, probable, pseudocell.
Crystal Structure
Load
Unit Cell | Unit Cell Packed
2x2x2 | 3x3x3 | 4x4x4
Unit Cell | Unit Cell Packed
2x2x2 | 3x3x3 | 4x4x4
Show
Big Balls | Small Balls | Just Balls | Spacefill
Polyhedra Off | Si Polyhedra | All Polyhedra
Remove metal-metal sticks
Big Balls | Small Balls | Just Balls | Spacefill
Polyhedra Off | Si Polyhedra | All Polyhedra
Remove metal-metal sticks
Display Options
Black Background | White Background
Perspective On | Perspective Off
2D | Stereo | Red-Blue | Red-Cyan
Black Background | White Background
Perspective On | Perspective Off
2D | Stereo | Red-Blue | Red-Cyan
View
CIF File Best | x | y | z | a | b | c
CIF File Best | x | y | z | a | b | c
Rotation
Stop | Start
Stop | Start
Labels
Console Off | On | Grey | Yellow
Console Off | On | Grey | Yellow
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) |
|---|---|---|---|---|---|---|---|
| 0005638 | Masuyite | Burns P C, Hanchar J M (1999) The structure of masuyite, Pb[(UO2)3O3(OH)2](H2O)3, and its relationship to protasite The Canadian Mineralogist 37 1483-1491 |  | 1999 | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 7.08 Å | (100) |
| 3.52 Å | (70) |
| 3.12 Å | (50) |
| 3.56 Å | (35) |
| 3.48 Å | (21) |
| 2.008 Å | (18) |
| 1.95 Å | (17b) |
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 Masuyite
General Appearance of Type Material:
Small (0.1 mm), pseudo-hexagonal, orange-red scales.
Place of Conservation of Type Material:
Type material is lost; Royal Museum of Central Africa, Tervuren, Belgium has neotype material; Harvard University, Cambridge, Massachusetts, USA, 104455, although supplied as a type by Vaes, does not contain lead, found microchemically in original type material.
Associated Minerals at Type Locality:
Other Language Names for Masuyite
Common Associates
Associations Based on Photo Data:
| 25 photos of Masuyite associated with Uraninite | UO2 |
| 20 photos of Masuyite associated with Uranophane | Ca(UO2)2(SiO3OH)2 · 5H2O |
| 10 photos of Masuyite associated with Richetite | (Fe3+,Mg)Pb 8.6(UO2)36O36(OH)24 · 41H2O |
| 6 photos of Masuyite associated with Rutherfordine | (UO2)CO3 |
| 6 photos of Masuyite associated with Kamotoite-(Y) | Y2(UO2)4(CO3)3O4 · 14H2O |
| 6 photos of Masuyite associated with Becquerelite | Ca(UO2)6O4(OH)6 · 8H2O |
| 4 photos of Masuyite associated with Sklodowskite | Mg(UO2)2(SiO3OH)2 · 6H2O |
| 3 photos of Masuyite associated with Studtite | [(UO2)(O2)(H2O)2] · H2O |
| 3 photos of Masuyite associated with Wölsendorfite | Pb7(UO2)14O19(OH)4 · 12H2O |
| 3 photos of Masuyite associated with Curite | Pb3(H2O)2[(UO2)4O4(OH)3]2 |
Related Minerals - Strunz-mindat Grouping
| 4.GB.05 | Rameauite | K2Ca(UO2)6O6(OH)4 · 6H2O |
| 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.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) | 61.9146% | 15,478,650 | 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 Masuyite
mindat.org URL:
https://www.mindat.org/min-2589.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 Masuyite
Reference List:
Burns, P. C., Hanchar, J. M. (1999) The structure of masuyite, Pb[(UO2)3O3(OH)2](H2O)3, and its relationship to protasite. The Canadian Mineralogist, 37 (6) 1483-1491
Localities for Masuyite
Showing 36 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.
Argentina | |
| Morello (2016) |
Australia | |
| |
| Georges FAVREAU collection & EDX ... |
Brazil | |
| Pires et al. (2014) |
Canada | |
| King (n.d.) |
| Rich et al. (1977) | |
Czech Republic | |
| Pauliš P. et al. (Kutna Hora, issue 1) |
| Ondruš et al. (1989) +1 other reference |
| Hloušek et al. (2002) |
| Möhn et al. (12/2021) | |
| Desor (04/2022) |
| Pauliš P. et al. (Kutna Hora, issue 1) |
| Pauliš et al. (2004) |
DR Congo (TL) | |
| KMMA +2 other references |
| |
| Wilson (2018) |
Egypt | |
| B.H. Ali et al. (2008) |
Finland | |
| Al-Ani et al. (2011) +2 other references |
| Al-Ani et al. (2011) |
France | |
| P.-C. Guiollard (2002) |
| Caubel (1997) |
| Henriot et al. (1998) |
| - (1998) | |
Germany | |
| Witzke (2024) |
India | |
| Current Science |
Italy | |
| Campostrini et al. (2006) |
| Campostrini et al. (2005) |
Norway | |
| Larsen (2025) |
Poland | |
| Kucha H. 2007: Mineralogia kruszcowa i ... |
Russia | |
| Pavel M. Kartashov analytical data (2014) |
| Pavel M. Kartashov analytical data (2012) |
Switzerland | |
| Meisser (2012) |
| Meisser (2012) |
| Stalder et al. (1998) |
| Stalder et al. (1998) | |
Zambia | |
| Cech et al. (1973) +1 other reference |
Quick NavTopAbout MasuyiteUnique IdentifiersIMA Classification Classification Mineral SymbolsPhysical Properties Optical Data Chemistry Crystallography Crystal StructureX-Ray Powder DiffractionGeological EnvironmentType Occurrence Other LanguagesCommon AssociatesStrunz-MindatRadioactivityOther InformationInternet Links References Localities Locality List
Shinkolobwe Mine, Shinkolobwe, Kambove Territory, Haut-Katanga, DR Congo