Soddyite

 IMA-GP
Uranium 53.3.3.1
(Dana Classification Number)
(Images) 8/B.36-10
(Strunz ID)

Property Data Remarks
Named for: Frederick Soddy (1877-1956), English radiochemist who worked with Rutherford. Coined the term 'isotope' to describe forms of the same element differing in atomic mass.
Alternate
    Name(s):
  		•  
    Mineral Class:
    Silicates
      NesosilicatesNesosilicates
    "Insel" silicates with anions unfamiliar to tetraheders.
    Uranyl-"Insel" silicates with [UO2]2+ - [SiO4]-4
        Soddyite - Swamboite series
    		 
    Chemical
        Formula:    		 (UO2)2SiO4 · 2H2O  
    Chemical
        Composition:
    Hydrogen: (H) 0.60%
    Oxygen: (O) 23.95%
    Silicon: (Si) 4.20%
    Uranium: (U) 71.25%
    		by weight
    Molecular
        Weight:    		 668.17 daltons (amu)
    Specific
        Radioactivity:

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

    Specific Activity Dose Rate
    Becquerels Curies milliRems/hour microSieverts/hour
    1.27534 × 1005 3.45 × 10-06 1.69 168.53

    Estimated Average Annual Exposure: 360 mRem (3.6 milliSieverts)
    Crystalography:
    System: Orthorhombic - Dipyramidal
    Axial Ratios: a: 0.7421
    b: 1
    c: 1.669
    Cell Dimensions: a: 8.32 Å
    b: 11.21 Å
    c: 18.71 Å
    Z: 8
    V: 1,745.03 Å3
    DenCalc: 5.09
    H-M Symbol: 2/m 2/m 2/m
    Space Group: Fddd
    X-Ray Diffraction:
      By Intensity ( I/Io )    		 (1): 4.57 Å
    (0.9): 3.36 Å
    (0.9): 6.28 Å
    		Soddyite
    Crystal
    (As Observed)
    Habit:
  • Prismatic
  • Striated
  • Pyramidal
    		•   
    Cleavage:
    [001] Perfect
    [111] Good
    		 
    Fracture:    
    Moh's
        Hardness:    		 3 - 4  
    Density: 4.627 grams/cm3
    Color: Yellow, Pale Yellow, Canary yellow, Yellowish green, Amber  
    Streak: Yellow  
    Luster: Vitreous  
    Diaphaneity: Transparent to Translucent  
    Pleochroism:
    (x): Colorless
    (y:) Pale Yellow
    (z:) Pale Yellow Green
    		 
    Ultra Violet
        Fluorescence:    		 Fluorescent  
    Magnetism: Non-magnetic  
    Occurance:
  • In oxidized uranium ores, with curite
    		•   
    Associated
        Minerals:

    Arsenopyrite, Autunite, Barite, Becquerelite, Billietite, Bismuth, Calcite, Chalcocite, Chalcopyrite, Cuprosklodowskite, Curite, Dewindtite, Dolomite, Galena, Hematite, Johannite, Kasolite, Malachite, Marcasite, Masuyite, Meta-Autunite, Metatorbernite, Muscovite, Novácekite, Parsonsite, Phosphuranylite, Pyrite, Pyrrhotite, Quartz, Saléeite, Schoepite, Sklodowskite, Sphalerite, Tetrahedrite, Torbernite, Uraninite, Uranophane, Uranophane-beta, Uranopilite, Vandenbrandeite, Vandendriesscheite, Wulfenite, Wurtzite, Zeunerite, Zippeite

    Mineral   -   > 75% of sites
    Mineral   -   > 50% of sites
    Mineral   -   > 25% of sites
    Minerals   -   Uranium & Thorium
    mineral links

    		These are minerals known to be found with Soddyite
    Locations:

    Somewhat Common Uranium Mineral

    Soddyite Locations
    Notes:

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

    Soddyite Images

    Specimen #1
    (001a) (001b) (001c) (001d)
    (001e) (001f)
    Swambo (Kambove), Shaba (Katanga), Congo (Zaïre)


    Specimen Notes

    Occurrence - The Soddyite occurs on a fine grained sandstone that contains embedded Uraninite, often in the form of crystals (image (001b), center of upper right quadrant). It appears that the Uraninite may have been deposited with the sand prior to bonding to sandstone.

     

    Habit - Soddyite appears to prefer forming in masses or twins. As in Feancevillite, the twinning causes a distortion of the crystal form observed. Only those crystals that form free of a twin show the true crystal form.

    Having no -1 valence anions, Soddyite forms directly on the sandstone, requiring no Aragonnite or Calcite substrate. It is a silicate like Coffinite, but differs from Coffinite in that it is a uranyl compound, while Coffinite is not.

    Crystals - The specimen has only one crystal that is solitary (001e). This one crystal, and the several other crystals that are not modified by twinning or intergrowth, all show the Orthorhombic Dipyramidal shape of Soddyite.

    Many crystals also show striations parallel to the [001] face. This may be due to variations in the mother liquor from which they grew.

    Apprearence - Many of the crystals, especially those in more protected areas, show considerable darkening. It is not known what may have caused this to occur.

    Luster - The luster of the Soddyite varies considerably. Most of the darkened crystals are dull, nearly earthy, as are many of the lighter greenish-yellow crystals. On the lighter crystals, the luster is mostly vitreous, but can be resinous on some surfaces.

    Diaphaneity - The crystals are nearly all transluscent, with a few appearing to be opaque.

     

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    Specimen Physical Properties
    Weight: x grams    
    g-Radiation Level:   cmp   msieverts background: 20 cpm