Uranocircite

 IMA-GP
Uranium 40.2a.3.1
(Dana Classification Number)
(Images) 7/E.01-110
(Strunz ID)
Unless sealed in glass, all specimens should be considered to have become Meta-Uranocircite within a few months of being exposed to ambient air.

Property Data Remarks
Named for: Its composition, and the Greek for falcon - refering to Falkenstein, Saxony, Germany, where it is commonly found
Alternate
    Name(s):
  		•  
    Mineral Class:
    Phosphates, Arsenates and Vanadates
      Uranylphosphates and uranylvanadates with
    [UO2]2+ - [PO4 | AsO4]3- and
    [UO2]2+ - [V2O8]6-
        Autunite group
    		 
    Chemical
        Formula:    		 Ba(UO2)2(PO4)2 · 10-12H2O  
    Chemical
        Composition:
    Barium: (Ba) 12.67%
    Hydrogen: (H) 2.23%
    Oxygen: (O) 35.44%
    Phosphorus: (P) 5.72%
    Uranium: (U) 43.94%
    		by weight
    Molecular
        Weight:    		 1,083.51 daltons (amu)
    Specific
        Radioactivity:

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

    Specific Activity Dose Rate
    Becquerels Curies milliRems/hour microSieverts/hour
    7.8647 × 1004 2.13 × 10-06 1.10 110.45

    Estimated Average Annual Exposure: 360 mRem (3.6 milliSieverts)
    Crystalography:
    System: Tetragonal - Ditetragonal Dipyramidal
    Axial Ratios: a:c = 1:2.91868
    Cell Dimensions: a = 7.01, c = 20.46, Z = 2; V = 1,005.41 Den(Calc) = 3.58
    H-M Symbol: 4/m 2/m 2/m
    Space Group: P4/nnc
    X Ray Diffraction: By Intensity(I/Io): 2.04(1) 5.1(1) 10.1(0.6)
    		 
    Habit:
  • Platy square crystals, usually in bladed aggregates
  • Micaceous, parallel growths having a "deck of cards" look
  • Crusts
  • Foliated aggregates
  • Scaly aggregates
  • Rosettes
    		•   
    Cleavage:
    [001] Perfect
    [010]
    [100] Distinct

    Cleavage sheets are slightly bendable.

    		  
    Fracture: Uneven, flexible  
    Moh's
        Hardness:    		 2 - 2.5  
    Density: 3.46 - 3.53 grams/cm3
    Color: Yellow to light Yellow-green  
    Streak: Light yellow  
    Luster: Vitreous, to Pearly on the main pinacoid  
    Diaphaneity: Transparent  
    Pleochroism:
    (x):
    (y:)
    (z:)
    		 
    Ultra Violet
        Fluorescence:
    Long Wave: Green
    Short Wave: Green
    		 
    Magnetism: Non-magnetic  
    Occurance:
  • Coating on metamorphic granite
  		•   
    Associated
        Minerals:

    Arsenopyrite, Autunite, Barite, Calcite, Chalcopyrite, Dewindtite, Fluorite, Galena, Hematite, Kasolite, Marcasite, Meta-Autunite, Parsonsite, Phosphuranylite, Pyrite, Pyrrhotite, Quartz, Sabugalite, Safflorite, Torbernite, Uraninite, Pitchblende, Uranophane, Uranopilite

    Mineral   -   > 39% of sites
    Mineral   -   > 29% of sites
    Mineral   -   > 19% of sites
    Minerals   -   Uranium & Thorium
    mineral links

    		These are minerals known to be found with Uranocircite
    Locations:

    Relatively common

    Uranocircite Locations
    Notes:

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

    Uranocircite can be difficult to distinguish from Autunite by ordinary means. However, Uranocircite is slightly heavier, its color is usually more yellow, and its fluorescent color is more green.

    Uranocircite can lose water and convert to a different mineral called meta-Uranocircite of the meta-autunite/meta-torbernite group of minerals. The change to meta-Uranocircite will often produce a pseudomorph.

    Crystals are probably metamict.

    Uranocircite Images

    Image courtesy of
    The Arkenstone
    Malacacheta, Minas Gerais, Brazil  
    Bergen, Falkenstein, Vogtland, Saxony, Germany