Marecottite

 IMA-2001-056; 2003
Uranium 31.10.4.7
(Dana Classification Number)
(No Images) 6/X.00-00
(Strunz ID)

Property Data Remarks
Named for: Les Marecottes, Switzerland, its type locality
Alternate
    Name(s):
  		•  
    Mineral Class:
    Sulfates, Chromates, Molybdates and Tungstates
      Unclassified Strunz Sulfates, Chromates, Molybdates and Tungstates
        Sulfate, Basic Hydrated
    		 
    Chemical
        Formula:    		 Mg3(H2O)18[(UO2)4O3(SO4)2]2 · 10(H2O)  
    Chemical
        Composition:
    Hydrogen: (H) 1.78%
    Magnesium: (Mg) 1.63%
    Manganese: (Mn) 1.34%
    Oxygen: (O) 33.21%
    Sulfur: (S) 3.91%
    Uranium: (U) 58.12%
    		by weight
    Molecular
        Weight:    		 3,276.34 daltons (amu)
    Specific
        Radioactivity:

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

    Specific Activity Dose Rate
    Becquerels Curies milliRems/hour microSieverts/hour
    1.04036 × 1005 2.81 × 10-06 1.44 144.01

    Estimated Average Annual Exposure: 360 mRem (3.6 milliSieverts)
    Crystalography:
    System: Triclinic - Pinacoidal
    Axial Ratios: a: 0.9614
    b: 1
    c: 1.2313
    Cell Dimensions: a: 10.815 Å
    b: 11.249 Å
    c: 13.851 Å
    Z: 1
    a: 66.224°
    b: 72.412°
    g: 69.95°
    V: 1,380.89 Å3
    DenCalc: 3.94
    H-M Symbol: -1
    Space Group: P-1
    X-Ray Diffraction:
      By Intensity ( I/Io )    		 (1): 9.47 Å (011)
    (0.8): 3.44 Å (013)
    (0.8): 4.74 Å (022)
    (0.7): 3.38 Å (022)
    (0.3): 2.876 Å (303)
    (0.2): 3.07 Å (301)
    (0.2): 3.11 Å (004)
    (0.2): 3.16 Å (033)
    (0.2): 6.29 Å
    		 
    Habit:
  • Triangular crystals up to 3 mm
  • Platy
  • Rosettes
    		•   
    Cleavage:
    [011] Perfect
    		 
    Fracture: Brittle  
    Moh's
        Hardness:    		 3  
    Density: 4.03 grams/cm3
    Color: Yellow-orange, Orange-yellow, Reddish-yellow  
    Streak: Colorless  
    Luster: Vitreous  
    Diaphaneity: Transparent  
    Pleochroism:
    (x):  
    (y:)  
    (z:)  
    		 
    Ultra Violet
        Fluorescence:
    Long Wave:  
    Short Wave:  
    		 
    Magnetism: Non-magnetic  
    Occurance:
  • Secondary mineral from the oxidation of sulfides in uranium-bearing deposits, formed at low pH (<5)
  		•   
    Associated
        Minerals:

    Anatase, Arsenopyrite, Arsenuranospathite, Becquerelite, Bieberite, Bismuth, Bismuthinite, Calcite, Cerussite, Chalcopyrite, Compreignacite, Copper, Dewindtite, Fourmarierite, Galena, Goethite, Hematite, Jarosite, Johannite, Jáchymovite, Kasolite, Magnesium-Zippeite, Malachite, Marcasite, Masuyite, Metatorbernite, Novácekite, Plumbojarosite, Pyrite, Quartz, Rabbittite, Rabejacite, Rutile, Sklodowskite, Sodium-Zippeite, Sphalerite, Uraninite, Uranophane, Uranopilite, Uranospinite, Vandendriesscheite, Zeunerite, Zippeite

    Mineral   -   All of the sites
    Mineral   -   > 67% of sites
    Minerals   -   Uranium & Thorium
    mineral links

    		These are minerals known to be found with Marecottite
    Locations:

    Very rare

    Locations list
    Notes:

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

    Crystals are probably metamic.