Clarkeite

 IMA-GP
Uranium 5.4.1.1
(Dana Classification Number)
(No Images) 5/H.05-10
(Strunz ID)

Property Data Remarks
Named for: Frank Wigglesworth Clarke (1847-1931), geochemist, U.S. Geological Survey
Alternate
    Name(s):
  		•  
    Mineral Class:
    Oxides
      Uranyl ([UO2]2+) hydroxides and hydrates
        Clarkeite
    		 
    Chemical
        Formula:    		 (Na,Ca,Pb)(UO2)O(OH) · 0-1H2O

    or

    (Na,Ca,Pb)2U2(O,OH)7    		  
    Chemical
        Composition:
    Calcium: (Ca) 1.26%
    Hydrogen: (H) 0.41%
    Lead: (Pb) 6.50%
    Oxygen: (O) 19.58%
    Sodium: (Na) 5.05%
    Uranium: (U) 67.21%
    		by weight
    Molecular
        Weight:    		 318.75 daltons (amu)
    Specific
        Radioactivity:

    (All radiation is for a 1 gram, fully aged specimen)

    Specific Activity Dose Rate
    Becquerels Curies milliRems/hour microSieverts/hour
    1.20301 × 1005 3.25 × 10-06 1.57 15.74

    Estimated Average Annual Exposure: 360 mRem (3.6 milliSieverts)
    Crystalography:
    System: Trigonal - Hexagonal Scalenohedral
    Axial Ratios: a: 1
    c: 4.48406
    Cell Dimensions: a: 3.954 Å
    c: 17.73 Å
    Z: 3
    V: 240.06 Å3
    DenCalc: 6.61
    H-M Symbol: -3 2/m
    Space Group: R-3m
    X-Ray Diffraction:
      By Intensity ( I/Io )    		 (1): 3.195 Å
    (0.64): 5.903 Å
    (0.56): 3.365 Å
    		 
    Habit:
  • Massive
  • Coarse Aggregates
    		•   
    Cleavage: None  
    Fracture: Conchoidal  
    Moh's
        Hardness:    		 4 - 4.5  
    Density: 6.39 grams/cm3
    Color: Dark brown, Brown-yellow  
    Streak: Yellowish brown  
    Luster: Resinous  
    Diaphaneity: Translucent to opaque  
    Pleochroism:
    (x): Dark orange
    (y:) Less dark orange
    (z:) More dark orange
    		 
    Ultra Violet
        Fluorescence:    		 Non-fluorescent  
    Magnetism: Non-magnetic  
    Occurance:
  • Replacing uraninite, as a late-stage hydrothermal alteration product
    		•   
    Associated
        Minerals:

    Albite, Almandine, Anatase, Anglesite, Arsenopyrite, Autunite, Becquerelite, Bertrandite, Beryl, Bismuth, Cassiterite, Chalcopyrite, Chrysoberyl, Curite, Fluorapatite, Fluorite, Fourmarierite, Galena, Goethite, 'Gummite', Hematite, Kaolinite, Kasolite, Lepidolite, Liebigite, Löllingite, Manganite, Marcasite, Meta-Autunite, Metatorbernite, Microcline, Montmorillonite, Muscovite, Opal, Parsonsite, Phosphuranylite, Quartz var: Rose Quartz, Reddingite, Rhodochrosite, Rutherfordine, Schorl, Siderite, Sphalerite, Strengite, Topaz, Torbernite, Triphylite, Uraninite, Uranophane, Uranophane-beta, Uranospinite, Vandendriesscheite, Vivianite, Zircon

    Mineral   -   > 50% of sites
    Mineral   -   > 25% of sites
    Mineral   -   > 15% of sites
    Minerals   -   Uranium & Thorium
    mineral links

    		These are minerals known to be found with Clarkeite
    Localities:

    Rare

    Clarkeite Localities
    Notes:

    Strongly radioactive a- and b-particles, g-rays.