Metatyuyamunite
A valid IMA mineral species - grandfathered
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About Metatyuyamunite
Formula:
Ca(UO2)2(VO4)2 · 3H2O
Previously assumed to have 3-5 water molecules per formula unit.
Colour:
Bright yellow
Lustre:
Resinous, Waxy
Hardness:
2
Specific Gravity:
3.81 - 3.93
Crystal System:
Orthorhombic
Member of:
Name:
Named in 1953 by Alice Mary Dowse Weeks, Mary E. Thompson, and Raymond B. Thompson for prefix meta- indicating a dehydration relationship to tyuyamunite.
Co-Type Localities:
Isostructural with:
Visually indistinguishable from tyuyamunite or similar uranyl vanadates. May spontaneously dehydrate in dry atmosphere from tyuyamunite.
Unique Identifiers
Mindat ID:
2690
Long-form identifier:
mindat:1:1:2690:7
Classification of Metatyuyamunite
Francevillite sheet topology
The sheet topology found in minerals of the carnotite group.
IMA Classification of Metatyuyamunite
Approved, 'Grandfathered' (first described prior to 1959)
IMA Formula:
Ca(U6+O2)2(V5+O4)2·3H2O
First published:
1953
Type description reference:
4.HB.25
4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
H : V[5,6] Vanadates
B : Uranyl Sorovanodates
4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
H : V[5,6] Vanadates
B : Uranyl Sorovanodates
40.2a.26.2
40 : HYDRATED NORMAL PHOSPHATES,ARSENATES AND VANADATES
2a : AB2(XO4)2·xH2O, containing (UO2)2+
40 : HYDRATED NORMAL PHOSPHATES,ARSENATES AND VANADATES
2a : AB2(XO4)2·xH2O, containing (UO2)2+
21.4.7
21 : Vanadates (and vanadates with arsenate or phosphate)
4 : Vanadates of U, Mn, Fe or Ni
21 : Vanadates (and vanadates with arsenate or phosphate)
4 : Vanadates of U, Mn, Fe or Ni
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 |
|---|---|---|
| Mtyu | 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 Metatyuyamunite
Resinous, Waxy
Transparency:
Translucent
Colour:
Bright yellow
Streak:
Yellow
Hardness:
2 on Mohs scale
Hardness Data:
Mohs hardness reference species
Tenacity:
Sectile
Cleavage:
Perfect
{001}
{001}
Density:
3.81 - 3.93 g/cm3 (Measured) 3.85 g/cm3 (Calculated)
Optical Data of Metatyuyamunite
Type:
Biaxial (-)
RI values:
nα = 1.62 - 1.68 nβ = 1.835 - 1.842 nγ = 1.865 - 1.899
2V:
Measured: 45° , Calculated: 44°
Birefringence:
0.2
Max. Birefringence:
δ = 0.219 - 0.245
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:
r > v strong
Optical Extinction:
XYZ = cab
Pleochroism:
Weak
Comments:
X = colorless
Y= very pale canary yellow
Z = pale canary yellow
Y= very pale canary yellow
Z = pale canary yellow
Chemistry of Metatyuyamunite
Mindat Formula:
Ca(UO2)2(VO4)2 · 3H2O
Previously assumed to have 3-5 water molecules per formula unit.
Previously assumed to have 3-5 water molecules per formula unit.
Element Weights:
Crystallography of Metatyuyamunite
Crystal System:
Orthorhombic
Class (H-M):
mmm(2/m2/m2/m) - Dipyramidal
Cell Parameters:
a = 10.54 Å, b = 8.49 Å, c = 17.34 Å
Ratio:
a:b:c = 1.241 : 1 : 2.042
Unit Cell V:
1,551.66 ų (Calculated from Unit Cell)
Z:
4
Morphology:
Usually earthy granular, also rhombic platy crystals.
Comment:
Pnam
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 8.51 Å | (100) |
| 5.22 Å | (25) |
| 4.22 Å | (75) |
| 3.77 Å | (25) |
| 3.26 Å | (50b) |
| 3.05 Å | (50b) |
| 2.58 Å | (25) |
Comments:
See also ICDD 43-187
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Stage 7: Great Oxidation Event | <2.4 |
| 47e : [Vanadates, chromates, manganates] | |
| 47f : [Uranyl (U⁶⁺) minerals] |
Type Occurrence of Metatyuyamunite
Co-Type Localities:
General Appearance of Type Material:
Scales and laths, radial aggregates. Massive, compact to cryptocrystalline. Powdery.
Geological Setting of Type Material:
Sedimentary uranium deposit
Other Language Names for Metatyuyamunite
Relationship of Metatyuyamunite to other Species
Member of:
Other Members of Carnotite Group:
| Carnotite | K2(UO2)2(VO4)2 · 3H2O | Mon. 2/m : P21/b |
| Margaritasite | (Cs,K,H3O)2(UO2)2(VO4)2 · H2O | Mon. 2/m : P21/b |
| Metavanuralite | Al(UO2)2(VO4)2(OH) · 8H2O | Tric. |
| Sengierite | Cu2(UO2)2(VO4)2 · 6H2O | Mon. 2/m : P21/b |
| Strelkinite | Na2(UO2)2(VO4)2 · 6H2O | Orth. |
| Tyuyamunite | Ca(UO2)2(VO4)2 · 5-8H2O | Orth. mmm(2/m2/m2/m) : Pnna |
| Vanuralite | Al(UO2)2(V2O8)(OH) · 11H2O | Mon. 2/m |
Common Associates
Associations Based on Photo Data:
| 49 photos of Metatyuyamunite associated with Malachite | Cu2(CO3)(OH)2 |
| 8 photos of Metatyuyamunite associated with Bokite | (Al,Fe)1.3(V5+,V4+,Fe3+)8O20 · 7.5H2O |
| 7 photos of Metatyuyamunite associated with Quartz | SiO2 |
| 6 photos of Metatyuyamunite associated with Rauvite | Ca(UO2)2(V10O28) · 16H2O |
| 6 photos of Metatyuyamunite associated with Chrysocolla | Cu2-xAlx(H2-xSi2O5)(OH)4 · nH2O, x < 1 |
| 5 photos of Metatyuyamunite associated with Carnotite | K2(UO2)2(VO4)2 · 3H2O |
| 5 photos of Metatyuyamunite associated with Baryte | BaSO4 |
| 5 photos of Metatyuyamunite associated with Hewettite | CaV6O16 · 9H2O |
| 5 photos of Metatyuyamunite associated with Uraninite | UO2 |
| 4 photos of Metatyuyamunite associated with 'Sandstone' |
Related Minerals - Strunz-mindat Grouping
| 4.HB.X | Spanoite | Tl2[(UO2)2(V2O8)] |
| 4.HB.05 | Margaritasite | (Cs,K,H3O)2(UO2)2(VO4)2 · H2O |
| 4.HB.05 | Carnotite | K2(UO2)2(VO4)2 · 3H2O |
| 4.HB.10 | Sengierite | Cu2(UO2)2(VO4)2 · 6H2O |
| 4.HB.15 | Francevillite | Ba(UO2)2(VO4)2 · 5H2O |
| 4.HB.15 | Fritzscheite | Mn2+(UO2)2(VO4,PO4)2 · 4H2O |
| 4.HB.15 | Curienite | Pb(UO2)2(VO4)2 · 5H2O |
| 4.HB.15 | Finchite | Sr(UO2)2(V2O8) · 5H2O |
| 4.HB.20 | Vanuralite | Al(UO2)2(V2O8)(OH) · 11H2O |
| 4.HB.20 | Metavanuralite | Al(UO2)2(VO4)2(OH) · 8H2O |
| 4.HB.25 | Tyuyamunite | Ca(UO2)2(VO4)2 · 5-8H2O |
| 4.HB.30 | Strelkinite | Na2(UO2)2(VO4)2 · 6H2O |
| 4.HB.35 | Uvanite | U6+2V5+6O21 · 15H2O (?) |
| 4.HB.40 | Rauvite | Ca(UO2)2(V10O28) · 16H2O |
| 4.HB.45 | Vandermeerscheite | K2[(UO2)2V2O8] · 2H2O |
Radioactivity
Radioactivity:
| Element | % Content | Activity (Bq/kg) | Radiation Type |
|---|---|---|---|
| Uranium (U) | 55.0956% | 13,773,900 | 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 Metatyuyamunite
Not fluorescent in UV
Other Information
Health Risks:
Contains uranium - always wash hands after handling. Avoid inhaling dust when handling or breaking. Never lick or ingest. Avoid prolonged exposure in proximity of the body. Store away from inhabited areas.
Internet Links for Metatyuyamunite
mindat.org URL:
https://www.mindat.org/min-2690.html
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Please feel free to link to this page.
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References for Metatyuyamunite
Localities for Metatyuyamunite
Showing 163 localities.
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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.
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Mashamba West Mine, Sicomines copper-cobalt project, Mutshatsha, Lualaba, DR Congo