Grimselite

 IMA-A 1971-040
Uranium 15.2.6.1
(Dana Classification Number)
(Images) 5/F.02-10
(Strunz ID)

Caution
Grimselite is water soluble.

Property Data Remarks
Named for: Grimsel Region, Hasli Valley, Bern, Switzerland, its type locality
Alternate
    Name(s):
  		•  
    Mineral Class:
    Nitrates, Carbonates and Borates
      Uranylcarbonates ([UO2]+2 - [CO3]-2)
        Grimselite - Liebigite series
    		 
    Chemical
        Formula:    		 K3Na(UO2)(CO3)3 · H2O  
    Chemical
        Composition:
    Carbon: (C) 5.92%
    Hydrogen: (H) 0.33%
    Oxygen: (O) 31.56%
    Potassium: (K) 19.28%
    Sodium: (Na) 3.78%
    Uranium: (U) 39.13%
    		by weight
    Molecular
        Weight:    		 608.36 daltons (amu)
    Specific
        Radioactivity:

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

    Specific Activity Dose Rate
    Becquerels Curies milliRems/hour microSieverts/hour
    7.0042 × 1004 1.89 × 10-06 0.99 9.95

    Estimated Average Annual Exposure: 360 mRem (3.6 milliSieverts)
    Crystalography:
    System: Hexagonal - Ditrigonal Dipyramidal
    Axial Ratios: a: 1
    c: 0.88817
    Cell Dimensions: a: 9.30 Å
    c: 8.26 Å
    Z: 2
    V: 618.70 Å3
    DenCalc: 3.27
    H-M Symbol: -6 m2
    Space Group: P-62c
    X-Ray Diffraction:
      By Intensity ( I/Io )    		 (1): 5.76 Å
    (0.8): 3.08 Å
    (0.8): 8.09 Å
    (0.7B): 3.65 Å
    (0.7): 2.67 Å
    		 
    Habit:
  • Microscopic crystals ( < 0.1 mm )
  • Granular aggregates
    		•   
    Cleavage: None  
    Fracture: Brittle - Conchoidal  
    Moh's
        Hardness:    		 2 - 2.5  
    Density: 3.3 grams/cm3
    Solubility: Water Soluble  
    Color: Pale yellow to Yellow  
    Streak: Light yellow  
    Luster: Earty (One Specimen Examined)
    Diaphaneity: Transluscent (One Specimen Examined)
    Pleochroism:
    (x):  
    (y:)  
    (z:)  
    Yes - no data available    		  
    Ultra Violet
        Fluorescence:    		 None (One Specimen Examined)
    Magnetism: Non-magnetic  
    Occurance:
  		•  
    Associated
        Minerals:

    Baylissite

    		 This is a mineral known to be found with Grimselite
    Localities:

    Extremely rare

    Grimselite Localities
    Notes:

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

    Crystals are probably metamic.

    Grimselite is one of the few minerals that is water soluble.

    Grimselite Images

    Specimen #1
    (001a) (001b) (001c) (001d)

     
    Gerstenegg - Sommerloch (Cable) Tunnel, Grimsel Pass, Hasli Tal, Bern canton, Schweiz (Switzerland)

    Specimen Notes

    Occurrence - The Grimselite occurs between quartz grains in a fine grained quartzite. The fragment shows considerable quartz dust across its entire surface, and blackish bits believed to be residue from explosives used in blasting. One vug is heavily discolored by this residue. Several masses of the Grimselite also appear scortched by the blasting.

    Solubility - Grimselite is reported in Minerals and their Locations to be soluble in water. No attempt was made to verify this as it would permanently damage the specimen. The Grimselite does not appear to be hygroscopic.

    Crystals - Crystals, while present, are too small to be examined at 30X magnification. Most of the Grinselite appears to be massive due to growth between quartz grains.

    Appearence - The specimen appears to have been quite close to the explosive charge that broke it loose from the earth. This is due to the nummerous particles of blackish residue in some areas, and the vug in image (001c) being almost completely scortched and discolored.

    Diaphaniety - The Grimselite is transluscent, though a few areas show greater clearity than the others.

    Luster - The luster of the Grimselite is earthy. It is uncertain if this is due to the effect of the blasting or is its true luster. A few area, those that are clearer than the rest of the Grimselite, do show a somewhat resinous luster.

    Pleochroism - Grimselite is reported to be pleochroic, which can be seen in the images (do not confuse the scortched mineral for pleochroism)

     

    Ultra Violet Fluorescence - No fluorescence of the Grimselite in either long or short wavelength ultra violet light was noticed. However, the quartzite did fluoresce weakly in short wave u.v. light, and considerably more weakly in long wave.

    The small individual particles of quartz dust did npt appear to fluoresce any differently than the solid quartzite. However, the clusters of material that look like dirty sugar crystals, in the left half of image (001c), do fluoresce very strongly. As these are closely associated with scortched areas, particularly the burnt out vug, they may be particles of undetonated explosive.

      -  

     

    Specimen Physical Properties
    Size 1.0 cm 0.9 cm 0.4 cm
    Weight: x grams    
    g-Radiation Level: (too small to measure)   msieverts background: 20 cpm