Demesmaekerite

 IMA-A 1965-019
Uranium 34.7.6.1
(Dana Classification Number)
(Images) 4/K.11-40
(Strunz ID)

Property Data Remarks
Named for: Gaston Demesmaeker (1911-), Belgian mining geologist, who studied the Shikolobwe uranium deposits
Alternate
    Name(s):
  		•  
    Mineral Class:
    Oxides
      Uranyl-Selenides with [UO2]2+ - [SeO3]2- groups
        Derriksite - Demesmaekerite series
    		 
    Chemical
        Formula:    		 Pb2Cu5(UO2)2(SeO3)6(OH)6 · 2H2O  
    Chemical
        Composition:
    Copper: (Cu) 14.63%
    Hydrogen: (H) 0.46%
    Lead: (Pb) 19.08%
    Oxygen: (O) 22.10%
    Selenium: (Se) 21.81%
    Uranium: (U) 21.92%
    		by weight
    Molecular
        Weight:    		 2,172.01 daltons (amu)
    Specific
        Radioactivity:

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

    Specific Activity Dose Rate
    Becquerels Curies milliRems/hour microSieverts/hour
    3.9233 × 1004 1.06 × 10-06 0.54 53.56

    Estimated Average Annual Exposure: 360 mRem (3.6 milliSieverts)
    Crystalography:
    System: Triclinic - Pinacoidal
    Axial Ratios: a: 1.1908
    b: 1
    c: 0.5617
    Cell Dimensions: a: 11.955 Å
    b: 10.039 Å
    c: 5.639 Å
    Z: 1
    a: 89.78°
    b: 100.37°
    g: 91.33°
    V: 665.53 Å3
    DenCalc: 5.42
    H-M Symbol: -1
    Space Group: P-1
    X-Ray Diffraction:
      By Intensity ( I/Io )    		 (1): 2.97 Å
    (0.8): 5.42 Å
    (0.6): 5.89 Å
    		 
    Habit:
  • Aggregates
    		•   
    Cleavage: None  
    Fracture:    
    Moh's
        Hardness:    		 3 - 4  
    Density: 5.28 grams/cm3
    Color: Aged Surface: Brown, Brownish green, Olive green, Bottle green to Dark green

    Fresh Surface: Light green    		  
    Streak:    
    Luster:    
    Diaphaneity: Translucent  
    Pleochroism:
    (x):  
    (y:)  
    (z:)  
    		 
    Ultra Violet
        Fluorescence:
    Long Wave:  
    Short Wave:  
    		 
    Magnetism: Non-magnetic  
    Occurance:
  • Lower part of the oxidation zone
    		•   
    Associated
        Minerals:

    Azurite, Barite, Becquerelite, Brochantite, Calcite var: Cobaltoan Calcite, Carrollite, Chalcocite, Chalcomenite, Cobaltomenite, Cornetite, Covellite, Cuprosklodowskite, Curite, Derriksite, Digenite, Francevillite, Gold, Guilleminite, Hematite, Heterogenite, Kasolite, Kolwezite, Malachite, Marthozite, Masuyite, Metatorbernite, Metatyuyamunite, Mottramite, Oosterboschite, Palladium, Rutherfordine, Schoepite, Sengierite, Sklodowskite, Soddyite, Sphaerocobaltite, Torbernite, Trogtalite, Tyuyamunite, Uraninite, Uranophane, Uranophane-beta, Vandenbrandeite, Vauquelinite, Wulfenite

    Minerals   -   Uranium & Thorium
    mineral links

    		These are minerals known to be found with Demesmaekerite
    Localities:

    Extremely rare

    Demesmaekerite Localities
    Notes:

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

    Demesmaekerite Images

    Specimen
    (001a) (001b) (001c) (001d)
      (001e) (001f)  
       
    Musonoi mine, Kolwezi, Shaba (Katanga), Congo (Zaïre)


    Specimen Notes

    This specimen was damaged, and an attempt made to glue it back together. This can best be seen in image 001b, where the crystal cluster does not meet the rock matrix. Crystal clusters located behind it and to the right it also were glue in place. In one area to the rear, the glue is visable. Image 001b is useful for seeing the crystal structure.

    Crystal Habit - Image 001a shows a radial cluster of elongated crystals. Image 001f shows this same cluster at a different angle. All of the elongated crystals are in radial clusters. The significance of this is not known.

    Color - The color of Demesmaekerite is given in most references as being dark green. This is seen on the specimen. However, as can be seen in images 001c, 001e and 001f, the freshly exposed Demesmaekerite is a light green. In image 001a, the more protected areas of the radial crystal cluster also show the light green color.

    Substrate - The Demesmaekerite grows on a substrate of Aragonite. On some areas of the specimen, this Aragonite is seen as botryoidal deposits, similar to that in caves. This is in agreement to the theory of hot radicles affecting the occurance of Uranyl minerals containing compact, highly reactive anions only forming on Calcite or Aragonite.

     

      -  

     

    Specimen Physical Properties
    Size   cm   cm   cm
    Weight: 19 grams   (includes Lucite mount)
    g-Radiation Level:   cmp   msieverts background: 20 cpm