Umohoite
A valid IMA mineral species - grandfathered
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About Umohoite
Formula:
(UO2)MoO4 · 2H2O
Colour:
Black, blue-black, dark green
Lustre:
Vitreous
Hardness:
2
Specific Gravity:
4.53 - 4.66
Crystal System:
Triclinic
Name:
The name reflects its composition: uranyl (U), molybdate (Mo) and water (H2O).
This page provides mineralogical data about Umohoite.
Unique Identifiers
Mindat ID:
4093
Long-form identifier:
mindat:1:1:4093:4
GUID
(UUID V4):
(UUID V4):
745e4d86-f98b-40f3-8443-164dd76deca9
IMA Classification of Umohoite
Approved, 'Grandfathered' (first described prior to 1959)
IMA Formula:
(UO2)(MoO4) · 2H2O
Classification of Umohoite
4.GC.10
4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
G : Uranyl Hydroxides
C : With additional cations; with mainly UO2(O,OH)6 hexagonal polyhedra
4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
G : Uranyl Hydroxides
C : With additional cations; with mainly UO2(O,OH)6 hexagonal polyhedra
49.2.2.1
49 : HYDRATED MOLYBDATES AND TUNGSTATES
2 : Hydrated Normal Molybdates and Tungstates
49 : HYDRATED MOLYBDATES AND TUNGSTATES
2 : Hydrated Normal Molybdates and Tungstates
27.3.8
27 : Sulphites, Chromates, Molybdates and Tungstates
3 : Molybdates
27 : Sulphites, Chromates, Molybdates and Tungstates
3 : Molybdates
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 |
|---|---|---|
| Umo | 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 Umohoite
Vitreous
Transparency:
Opaque
Colour:
Black, blue-black, dark green
Hardness:
2 on Mohs scale
Cleavage:
Perfect
Perfect on {001}
Perfect on {001}
Density:
4.53 - 4.66 g/cm3 (Measured) 4.49(3) g/cm3 (Calculated)
Optical Data of Umohoite
Type:
Biaxial (-)
RI values:
nα = 1.660 nβ = 1.831 nγ = 1.915
2V:
Measured: 65° , Calculated: 64°
Max Birefringence:
δ = 0.255
Image shows birefringence interference colour range (at 30µm thickness)
and does not take into account mineral colouration.
and does not take into account mineral colouration.
Surface Relief:
Very High
Dispersion:
weak r>v
Pleochroism:
Visible
Comments:
X= dark blue
Y= pale blue
Z= olive-green
Y= pale blue
Z= olive-green
Chemistry of Umohoite
Mindat Formula:
(UO2)MoO4 · 2H2O
Elements listed:
Crystallography of Umohoite
Crystal System:
Triclinic
Cell Parameters:
a = 14.6 Å, b = 7.5 Å, c = 6.38 Å
β = 99.08°
β = 99.08°
Ratio:
a:b:c = 1.947 : 1 : 0.851
Unit Cell V:
nan ų (Calculated from Unit Cell)
Z:
4
Morphology:
Tabular plates, rosettes, massive, disseminated, thin veinlets
Comment:
pseudorhombohedral
Crystal Structure
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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) |
|---|---|---|---|---|---|---|---|
| 0005655 | Umohoite | Krivovichev S V, Burns P C (2000) Crystal chemistry of uranyl molybdates. 1. The structure and formula of umohoite The Canadian Mineralogist 38 717-726 |  | 2000 | 0 | 293 | |
| 0017795 | Umohoite | Makarov E S, Anikina L I (1963) Crystal structure of umohoite (UMoO6(H2O)2)*2H2O Geochemistry 1 14-21 | 1963 | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 4.13 Å | (100) |
| 3.20 Å | (50) |
| 3.15 Å | (40) |
| 12.2 Å | (30) |
| 6.18 Å | (30) |
| 2.07 Å | (30) |
| 3.11 Å | (20) |
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] |
Geological Setting:
Secondary mineral in sediment hosted uranium deposits in zone above water table.
Type Occurrence of Umohoite
General Appearance of Type Material:
Small flat black flakes with triangular markings, in veinlets, and in disseminated grains.
Place of Conservation of Type Material:
No designated type material.
Associated Minerals at Type Locality:
Reference:
Brophy, G.P., Kerr, P.F. (1953) Hydrous uranium molybdate in Maryvale ore. in Annual Report for June 30, 1952 to April 1, 1953 RME-3046, U.S. Atomic Energy Commission: 45-51.
Other Language Names for Umohoite
Common Associates
Associated Minerals Based on Photo Data:
| 44 photos of Umohoite associated with Calcurmolite | Ca[(UO2)3(MoO4)2(OH)4](H2O)~5.0 |
| 27 photos of Umohoite associated with Parauranophane | Ca(UO2)2(SiO3OH)2 · 5H2O |
| 15 photos of Umohoite associated with Uranophane | Ca(UO2)2(SiO3OH)2 · 5H2O |
| 12 photos of Umohoite associated with Zeunerite | Cu(UO2)2(AsO4)2 · 12H2O |
| 9 photos of Umohoite associated with Iriginite | (UO2)Mo2O7 · 3H2O |
| 9 photos of Umohoite associated with Metaschoepite | (UO2)8O2(OH)12 · 10H2O |
| 8 photos of Umohoite associated with Hydronováčekite | Mg(UO2)2(AsO4)2 · 12H2O |
| 7 photos of Umohoite associated with Baryte | BaSO4 |
| 5 photos of Umohoite associated with Tyrolite | Ca2Cu9(AsO4)4(CO3)(OH)8 · 11H2O |
| 3 photos of Umohoite associated with Metaheinrichite | Ba(UO2)2(AsO4)2 · 8H2O |
Related Minerals - Strunz-mindat Grouping
| 4.GC. | Bobfinchite | Na[(UO2)8O3(OH)11] · 10H2O |
| 4.GC.05 | Clarkeite | (Na,Ca,Pb)(UO2)O(OH) · 0-1H2O |
| 4.GC.15 | Spriggite | Pb3(UO2)6O8(OH)2 · 3H2O |
Other Information
Notes:
HNO3 1:1 - effervesces, then turns yellow and yellow-brown.
FeCl2 20% - etches mineral strongly.
Aqua Regia - quickly and strongly etched.
HCl 1:1, KOH 40%, HgCl2 5%, H2O2, HCl Dil. 10% U.S.P. - all negative.
FeCl2 20% - etches mineral strongly.
Aqua Regia - quickly and strongly etched.
HCl 1:1, KOH 40%, HgCl2 5%, H2O2, HCl Dil. 10% U.S.P. - all negative.
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 Umohoite
mindat.org URL:
https://www.mindat.org/min-4093.html
Please feel free to link to this page.
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External Links:
References for Umohoite
Reference List:
Krivovichev, S. V., Burns, P. C. (2000) Crystal chemistry of uranyl molybdates. I. The structure and formula of umohoite. The Canadian Mineralogist, 38 (3) 717-726 doi:10.2113/gscanmin.38.3.717
Localities for Umohoite
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 | |
| 304 [286-287]. +2 other references |
Egypt | |
| Bisher (2012) |
France | |
| - (1998) |
| [MinRec 25:209 +2 other references |
| [Le Cahier des Micromonteurs |
Germany | |
| Desor (08/2020) |
| Rée et al. (1974) |
Indonesia | |
| Setiawan I et al. (2014) |
Kazakhstan | |
| Pekov (1998) +1 other reference |
Romania | |
| Szakáll (2002) |
| Szakáll (2002) | |
Slovakia | |
| Števko M. (2022) |
USA | |
| Anthony et al. (1995) |
| Bollin & Kerr (1958) +3 other references | |
| Northrop et al. (1996) +1 other reference |
| Smith (1991) |
| Econ Geol (1986) | |
| - (2005) |
| Page et al. (1956) +2 other references | |
| Bullock (1981) | |
| Brophy et al. (1953) +1 other reference |
| - (2005) |
| - (2005) |
| Krivovichev et al. (2000) |
Quick NavTopAbout UmohoiteUnique IdentifiersIMA Classification Classification Mineral SymbolsPhysical Properties Optical Data Chemistry Crystallography Crystal StructureX-Ray Powder DiffractionGeological EnvironmentType Occurrence Other LanguagesCommon AssociatesStrunz-MindatOther InformationInternet Links References Localities Locality List
Kyzylsai Mo-U deposit, Chu-Ili Mountains, Ulytau District, Ulytau Region, Kazakhstan