Carnotite

 IMA-GP
Uranium 40.2a.28.1
(Dana Classification Number)
(Images) 7/E.11-50
(Strunz ID)

Property Data Remarks
Named for: M. A. Carnot (1839-1920), French chemist
Alternate
    Name(s):
  		•  
    Mineral Class:
    Phosphates, Arsenates and Vanadates
      Uranylphosphates and uranylvanadates with:
    [UO2]2+ - [PO4 | AsO4]3- and [UO2]2+ - [V2O8]6-,
    uranyl-group vanadates with [UO2]2+ - [V2O8]6-
        Tyuyamunite series
    		 
    Chemical
        Formula:    		 K2(UO2)2(VO4)2 · 1-3H2O  
    Chemical
        Composition:
    Hydrogen: (H) 0.67%
    Oxygen: (O) 26.60%
    Potassium: (K) 8.67%
    Vanadium: (V) 11.29%
    Uranium: (U) 52.77%
    		by weight
    Molecular
        Weight:    		 902.18 daltons (amu)
    Specific
        Radioactivity:

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

    Specific Activity Dose Rate
    Becquerels Curies milliRems/hour microSieverts/hour
    9.4457 × 1004 2.55 × 10-06 1.29 129.16

    Estimated Average Annual Exposure: 360 mRem (3.6 milliSieverts)
    Crystalography:
    System: Monoclinic - Prismatic
    Axial Ratios: a: 1.2449
    b: 1
    c: 0.8216
    Cell Dimensions: a: 10.47 Å
    b: 8.41 Å
    c: 6.91 Å
    Z: 2
    b: 103.667°
    V: 591.22 Å3
    DenCalc: 5.07
    H-M Symbol: 2m
    Space Group: P21/a
    X-Ray Diffraction:
      By Intensity ( I/Io )    		 (1): 6.56 Å
    (0.7): 3.12 Å
    (0.5): 3.53 Å
    		 
    Habit:
  • Earthy (may be powdery)
  • Encrustations (may be powdery)
  • Plates (rare)
    		•   
    Cleavage:
    [001] Perfect
    [010]  
    [001]  
    		 
    Fracture: Uneven  
    Moh's
        Hardness:    		 2  
    Density: 3.7 - 4.7 (Dependant on water content) grams/cm3
    Color: Bright yellow, lemon yellow, greenish yellow, yellow-brown  
    Streak: Yellow to light yellow  
    Luster: Pearly to Dull or Earthy  
    Diaphaneity:    
    Pleochroism:
    (x):  
    (y:)  
    (z:)  
    		 
    Ultra Violet
        Fluorescence:
    Long Wave: None
    Short Wave: None
    		 
    Magnetism: Non-magnetic  
    Occurance:
  • Secondary mineral in association with uranium and vanadium minerals in sandstones and limestones
  • Conglomerates
  • Massive hydrothermal replacement deposits
    		•   
    Associated
        Minerals:

    Autunite, Azurite, Barite, Calcite, Chalcocite, Chalcopyrite, Chrysocolla, Coffinite, Copper, Cuprite, Dolomite, Fluorite, Francevillite, Galena, Goethite, Gypsum, Hematite, Jarosite, Liebigite, 'Limonite', Malachite, Marcasite, Meta-Autunite, Metatyuyamunite, Molybdenite, Pyrite, Pyrolusite, Quartz, Roscoelite, Schröckingerite, Selenium, Sphalerite, Torbernite, Tyuyamunite, Uraninite, Uranophane, Weeksite

    Mineral   -   > 25% of sites
    Mineral   -   > 8% of sites
    Minerals   -   Uranium & Thorium
    mineral links

    		These are minerals known to be found with Carnotite
    Localities:

    Uncommon

    Carnotite Localities
    Notes:

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

    Common enough to be an important ore of uranium and vanadium.

    Closely related to Tyuyamunite with potassium replacing calcium and a different percentage of water. Their crystal structures are different, Tyuyamunite is orthorhombic and Carnotite is monoclinic. The two minerals are often found together and are essentially indistiguishable by ordinary methods.

    Oxygenated water dissolves the uranium from primary uranium minerals, and the uranium is later deposited in reducing enviroments more favorable to the formation of carnotite. Since many deposits are in sandstones, associated with petrified trees and other fossils, it is reasonable to assume that the decaying material helped produce the required reducing enviroment.

    Carnotite Images

    Specimen #1
    (001aa) (001a) (001b)

    w. Uraninite
    in sandstone
    w. Uraninite
    in sandstone
    w. Uraninite
    in sandstone
    Colorado Plateau, U.S.A.
    (exact location unknown)


    Specimen Notes

    Occurrence - The Carnotite occurs as a disperced deposit in a dark sandstone, typical of many uranium deposits in the Colorado Plateau area. This is all that is known of its source location.

    In close proximity to the yellow Carnotite are deposits of black Uraninite. As the deposits occur as bands and 'nodules' within the sandstone, it is likely that they represent a type of fossil of a soft tissued creature, or colonies of bacteria.

    The general physical properties of the Carnotite and Uraninite cannot be determined from this specimen. The occurrance is in the form of hydrologic deposits within the sandstone matrix.

    Specimen Physical Properties
    Size 6.99 cm 3.81 cm 2.54 cm
    Weight: 54.15 grams 22° 42% R/H
    g-Radiation Level: 512 cmp
    (35 minute average)
    (476 cpm minimum)
    (567 cpm maximum)    		 0.512 msieverts background: 23 cpm