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Umohoite

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Rabejac, Lodève, Hérault, Languedoc-Roussillon, France
© Thomas Witzke

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Formula:
(UO
 
2
)MoO
 
4
·4H
 
2
O
System:TriclinicColour:Black, blue-black, dark ...
Hardness:2
Name:The name reflects its composition: uranyl (U), molybdate (Mo) and water (H2O).
This page provides mineralogical data about Umohoite.

Classification of Umohoite

IMA status:Valid - first described prior to 1959 (pre-IMA) - "Grandfathered"
Strunz 8th edition ID:6/G.05-20
Nickel-Strunz 10th (pending) edition ID: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
Dana 8th edition ID:49.2.2.1

49 : HYDRATED MOLYBDATES AND TUNGSTATES
2 : Hydrated Normal Molybdates and Tungstates
Hey's CIM Ref.:27.3.8

27 : Sulphites, Chromates, Molybdates and Tungstates
3 : Molybdates
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Type Occurrence of Umohoite

Type Locality:Freedom No. 2 Mine, Marysvale District (Marysvale Uranium area), Piute Co., Utah, USA
Year of Discovery:1953

Occurrences of Umohoite

Geological Setting:Secondary mineral in sediment hosted uranium deposits in zone above water table.

Physical Properties of Umohoite

Lustre:Vitreous
Diaphaneity (Transparency):Opaque
Colour:Black, blue-black, dark green
Hardness (Mohs):2
Cleavage:Perfect
Perfect on {001}
Density (measured):4.53 - 4.66 g/cm3
Density (calculated):4.49(3) g/cm3

Crystallography of Umohoite

Crystal System:Triclinic
Cell Parameters:a = 14.6Å, b = 7.5Å, c = 6.38Å
β = 99.08°
Ratio:a:b:c = 1.947 : 1 : 0.851
Unit Cell Volume:V nan ų (Calculated from Unit Cell)
Z:4
Morphology:Tabular plates, rosettes, massive, disseminated, thin veinlets
Comment:pseudorhombohedral

Optical Data of Umohoite

Type:Biaxial (-)
RI values: nα = 1.660 nβ = 1.831 nγ = 1.915
2V:Measured: 65° , Calculated: 64°
Maximum Birefringence:δ = 0.255

Chart shows birefringence interference colour range (at 30µm thickness) 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

Chemical Properties of Umohoite

Formula:
(UO
 
2
)MoO
 
4
·4H
 
2
O
Essential elements:H, Mo, O, U
All elements listed in formula:H, Mo, O, U

Relationship of Umohoite to other Species

Related Minerals - Nickel-Strunz Grouping):
4.GC.05Clarkeite
(Na,Ca,Pb)
 
2
U
 
2
(O,OH)
 
7
4.GC.15Spriggite
Pb
 
3
[(UO
 
2
)
 
6
|O
 
8
|(OH)
 
2
]·3H
 
2
O
Related Minerals - Hey's Index Grouping:
27.3.1Lindgrenite
Cu
 
3
[OH|MoO
 
4
]
 
2
27.3.2Powellite
Ca[MoO
 
4
]
27.3.3Wulfenite
Pb[MoO
 
4
]
27.3.4Koechlinite
(BiO)
 
2
[MoO
 
4
]
27.3.5Sedovite
U(MoO
 
4
)
 
2
27.3.6Mourite
UMo
 
5
O
 
12
(OH)
 
10
27.3.7Iriginite
UO
 
2
Mo
 
2
O
 
7
·3H
 
2
O
27.3.9Moluranite
U(UO
 
2
)
 
2
Mo
 
5
O
 
19
·12H
 
2
O ?
27.3.10Cousinite
MgU
 
2
Mo
 
2
O
 
11
·6H
 
2
O
27.3.11Calcurmolite
(Ca,Na)
 
2
(UO
 
2
)
 
3
Mo
 
2
(O,OH)
 
11
·nH
 
2
O
27.3.12Tengchongite
CaO·6UO
 
3
·2MoO
 
3
·12H
 
2
O
27.3.13Kamiokite
Fe
 
2
Mo
 
3
O
 
8
27.3.14Ferrimolybdite
Fe
 
2
[MoO
 
4
]
 
3
 · nH
 
2
O

Other Names for Umohoite

German names:
Umohoit
Russian names:
Умохоит
Spanish names:
Umohoita

Other Information

Health Warning:No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.

References for Umohoite

Reference List:Brophy, G.P. & Kerr, P.F. (1953): Hydrous uranium molybdate in Marysvale ore. Annual Report June 30, 1952 - April 1, 1953 U.S.Atomic Energy Comm., RME-3046, 45-51.

Rocks and Minerals (1953): 28: 480.

American Mineralogist (1957): 42: 657-660.

Makarov, E.S. and Anikina, L.I. (1963) Crystal structure of umohoite [UMoO6(H2O)2]·2H2O. Geochemistry: 14-21.

Krivovichev, S.V. and Burns, P.C. (2000a) Crystal chemistry of uranyl molybdates. I. The structure and formula of umohoite. Canadian Mineralogist: 38: 717-726.

Burns, P.C. (2005) U 6+ minerals and inorganic compounds: insights into an expanded structural hierarchy of crystal structures. Canadian Mineralogist: 43: 1839-1894.

Internet Links for Umohoite

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  • Raman and XRD data at RRUFF project
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    Localities for Umohoite

    Hide Locality List
    The map shows a selection of localities that have latitude and longitude coordinates recorded. Click on the symbol to view information about a locality. The symbol next to localities in the list can be used to jump to that position on the map.
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    (TL) indicates type locality. ? indicates mineral may be doubtful at this locality. All other localities listed without reference should be considered as uncertain and unproven until references can be found.
    Democratic Republic of Congo (Zaïre)
     
    • Katanga (Shaba)
      • Katanga Copper Crescent
        • Central area
          • Shinkolobwe
    		[MinRec 20:286-287]
    France
     
    • Languedoc-Roussillon
      • Hérault
        • Lodève
    		[Le Cahier des Micromonteurs, 1998, 2, p.13-26]
    [MinRec 25:209, 23:433]
    Le Règne Minéral, Hors Série IV (1998)
    Kazakhstan
     
    • Zhezqazghan Oblysy (Dzezkazgan Oblast'; Dzhezkazgan Oblast'; Djezkazgan Oblast'; Jezkazgan Oblast')
      • Balqash (Balkhash; Karatas) Region
        • Chu-Ili Mts
    		Can Min 38:717-726
    USA
     
    • Arizona
      • Coconino Co.
        • Cameron District
    		No reference listed
    Anthony, J.W., et al (1995), Mineralogy of Arizona, 3rd.ed.: 289, 406; Hamilton, P. & P.F. Kerr (1959), Umohoite from Cameron, AZ, Am.Min.: 44: 1248-1260; Keith (1970), AZ Bur. Mines Bull. 182: 103-159, 202-289; Bollin & Kerr (1958), Guidebook for New Mexico Geol.Soc., 9th. Field Conference F.P. 164-168.
    • New Mexico
      • Guadalupe Co.
    		Minerals of New Mexico 3rd ed.
    • Texas
      • Live Oak Co.
    		R&M 66:3 pp 196-224
    • Utah
      • Piute Co.
        • Antelope Range
          • Henry District (Durkee District)
    		U.S. Geological Survey, 2005, Mineral Resources Data System: U.S. Geological Survey, Reston, Virginia.
        • Marysvale District (Marysvale Uranium area)
    		UGMS Bull 117 Minerals and Mineral Localities of Utah
    Handbook of Mineralogy - Anthony, Bideaux, Bladh, Nichols
      • Sevier Co.
        • Gold Mountain District
    		U.S. Geological Survey, 2005, Mineral Resources Data System: U.S. Geological Survey, Reston, Virginia.
    • Wyoming
      • Fremont Co.
        • Gas Hills District
    		U.S. Geological Survey, 2005, Mineral Resources Data System: U.S. Geological Survey, Reston, Virginia.
    Can Min 38:717-726
    Mineral and/or Locality
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