Novácekite

 IMA-GP
Uranium 40.2a.10.1
(Dana Classification Number)
(No Images) 7/E.01-40
(Strunz ID)
Unless sealed in glass, all specimens should be considered to have become Metanovácekite within a few months of being exposed to ambient air.

There is some discussion as to if there are only one or if two crystal forms of this mineral occur.
The type II crystalographic data is the accepted data for a single form.  

Property Data Remarks
Named for: Radim Novácek (1905-1942), Czech minerologist
Alternate
    Name(s):
  • Novacikit
    		•   
    Mineral Class:
    Phosphates, Arsenates and Vanadates
      Uranylphosphates and uranylvanadates with
    [UO2]2+ - [PO4 | AsO4]3- and
    [UO2]2+ - [V2O8]6-
        Autunite group
    		 
    Chemical
        Formula:    		 Mg(UO2)2(AsO4)2 · 12H2O  
    Chemical
        Composition:
    Arsenic: (As) 14.16%
    Hydrogen: (H) 2.29%
    Magnesium: (Mg) 2.30%
    Oxygen: (O) 36.28%
    Uranium: (U) 44.98%
    		by weight
    Molecular
        Weight:    		 1,058.38 daltons (amu)
    Specific
        Radioactivity:

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

    Specific Activity Dose Rate
    Becquerels Curies milliRems/hour microSieverts/hour
    8.0514 × 1004 2.18 × 10-06 1.14 113.86

    Estimated Average Annual Exposure: 360 mRem (3.6 milliSieverts)
    Crystalography:
    System: Tetragonal - Dipyramidal
      Type I Type II
    Axial Ratios: a: 1 1
    c: 1.53846 2.82113
    Cell Dimensions: a: 14.30 Å 7.10 Å
    c: 22.0 Å 20.03 Å
    Z: 8 2
    V: Å3 1,014.08 Å3
    DenCalc: ~3.5 3.47
    H-M Symbol:   4/m
    Space Group: P42/n I4/mmm
    X-Ray Diffraction: By Intensity ( I/Io ) (0.8):   10.9 Å (1.0):   10.0 Å
    (0.6):   5.5 Å (0.8):   5.0 Å
    (1.0):   3.54 Å (0.4):   3.35 Å
    (0.7):   3.22 Å (0.4):   1.77 Å
      (0.5):   1.588 Å
    		X-ray diffraction and Type II data per Minerals and their Localities
    Habit:
  • Lamellar aggregates of platy crystals on {001} plane
  • Scaly crusts
    		•   
    Cleavage:
    [001] Perfect
    [010] Indistinct
    [110] Indistinct
    		 
    Fracture:    
    Moh's
        Hardness:    		 2.5  
    Density: 3.7 grams/cm3
    Color: Light yellow, Straw-yellow  
    Streak: Yellow white  
    Luster: Waxy to Vitreous  
    Diaphaneity: Transparent to Opaque  
    Dichroism:
    (e): Colorless
    (w:) Colorless
    		 
    Ultra Violet
        Fluorescence:
    Long Wave: Weak green to Yellowish green
    Short Wave: Weak green to Yellowish green
    		 
    Magnetism: Non-magnetic  
    Occurance:
  • Oxidation zone of uranium ores near or containing arsenic minerals
    		•   
    Associated
        Minerals:

    Acanthite, Anglesite, Annabergite, Aragonite, Arsenic, Arsenolite, Arsenopyrite, Arsenuranospathite, Autunite, Azurite, Barite, Barium-Pharmacosiderite, Bismuth, Bismuthinite, Bornite, Brochantite, Calcite, Cerussite, Chalcocite, Chalcopyrite, Chrysocolla, Coffinite, Copper, Covellite, Cuprite, Digenite, Dolomite, Erythrite, Fluorite, Galena, Goethite, Gypsum, Hematite, Kaolinite, Kasolite, Lavendulan, Löllingite, Malachite, Marcasite, Meta-Autunite, Metaheinrichite, Metanovácekite, Metatorbernite, Metazeunerite, Mixite, Nickeline, Pharmacolite, Proustite, Pyrite, Pyrolusite, Quartz, Rammelsbergite, Rutile, Safflorite, Schoepite, Scorodite, Silver, Sklodowskite, Skutterudite, Sphalerite, Tennantite, Tetrahedrite, Torbernite, Uraninite, Uranophane, Uranopilite, Uranospinite, Walpurgite, Zeunerite, Zippeite

    Mineral   -   > 67% of sites
    Mineral   -   > 50% of sites
    Mineral   -   > 25% of sites
    Minerals   -   Uranium & Thorium
    mineral links

    		These are minerals known to be found with Novácekite
    Locations: Rare

    Novácekite Locations
    Notes:

    Radioactive a- and b-particles, g-rays.

    Loses water to become meta-Novácekite.