Andersonite

 IMA-GP
Uranium 15.2.5.1
(Dana Classification Number)
(Images) 5/F.02-40
(Strunz ID)

Property Data Remarks
Named for: Charles Alfred Anderson (1902-1990), geologist, U.S. Geological Survey, and who found the mineral species
Alternate
    Name(s):
 
Mineral Class:
Nitrates, Carbonates and Borates
  Uranylcarbonates ([UO2]2+ - [CO3]2-)
    Grimselite - Liebigite series
 
Chemical
    Formula:		 Na2CaUO2(CO3)3 · 6H2O  
Chemical
    Composition:
Carbon: (C) 5.59%
Calcium: (Ca) 6.22%
Hydrogen: (H) 1.88%
Oxygen: (O) 42.22%
Sodium: (Na) 7.14%
Uranium: (U) 36.95%
by weight
Molecular
    Weight:		 644.20 daltons (amu)
Specific
    Radioactivity:

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

Specific Activity Dose Rate
Becquerels Curies milliRADs
per hour		 microSieverts
6.6139 × 1004 1.79 × 10-06 0.96 9.6

Estimated Average Annual Exposure: 3.6 RAD (3.6 centiSieverts)
Crystalography:
System: Trigonal - Rhombohedral
Crystal angles are close to 90°, making them pseudocubic.
Axial Ratios: a: 1
c: 1.32367
Cell Dimensions: a: 18.009 Å
c: 23.838 Å
Z: 18
V: 6,695.45 Å3
DenCalc: 2.88
H-M Symbol: -3
Space Group: R-3
X-Ray Diffraction:
  By Intensity ( I/Io )		 (1): 5.67 Å
(1): 7.93 Å
(1): 13 Å
 
Habit:
  • Druse - small rhombohedral crystals.
  • Occurs as well-formed pseudo cubic rhobohedral crystals.
  • Commonly found as masses filling cracks in the host rock.
  • Also commonly found as crusts formed by efflorescence on mine walls.
  
Cleavage: Perfect in three directions forming rhombs.  
Fracture: Conchoidal  
Moh's
    Hardness:		 2.5  
Density: 2.79 - 2.87 grams/cm3
Color: Yellow to a Yellowish green  
Streak: Pale yellow  
Luster: Vitreous to Pearly  
Diaphaniety: Transparent to Translucent  
Pleochroism:
(x):  
(y:)  
(z:)  
 
Ultra Violet
    Fluorescence:
Long Wave: Bright lemon-yellow
Short Wave: Bright lemon-yellow
Long & Short wave U.V. Fluorescence may be so strong it appears to be white
Magnetism: Non-magnetic  
Occurance:
  • Sandstone-hosted uranium deposits.
  • Andersonite is formed as an efflorescent crust in the dry air of uranium mines. Thus, some Andersonite specimens are the result of human intervention, and it is considered by some minerologists not to be a true natural mineral.
  
Associated
    Minerals:

Allophane, Aragonite, Arsenic, Arsenopyrite, Autunite, Azurite, Barite, Bayleyite, Becquerelite, Bornite, Brochantite, Calcite, Carnotite, Cassiterite, Chalcanthite, Chalcocite, Chalcopyrite, Coffinite, Cuprosklodowskite, Dolomite, Ferroselite, Fluorite, Galena, Goethite, Gypsum, Hematite, Jarosite, Johannite, Kaolinite, Liebigite, Malachite, Marcasite, Meta-Autunite, Metatorbernite, Metatyuyamunite, Metazeunerite, Molybdenite, Montroseite, Muscovite, Novácekite, Pyrite, Pyrrhotite, Quartz, Roscoelite, Schröckingerite, Selenium, Siderite, Sodium-Zippeite, Sphalerite, Tennantite, Torbernite, Tyuyamunite, Uraninite, Uranophane, Uranophane-beta, Uranopilite, Zeunerite, Zippeite

Mineral   -   > 57% of sites
Mineral   -   > 33% of sites
Mineral   -   > 14% of sites
Minerals   -   Uranium & Thorium
mineral links

These are minerals known to be found with Andersonite
Localities:

Rare

Andersonite Localities
Notes:

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

The fluorescence often is so strong that neighboring minerals are illuminated.

Crystals are probably metamic.

Andersonite Images

Specimen #1
(001aa) (001ab) (001ba) (001bb)

(white light)
(white light)
(white light)
(uv light)
(long/short identical)
(001ca) (001cb) (001e) (001g)

(white light)
(uv light)
(long/short identical)
(001da) (001db) (001ia) (001ib)

(white light)
(uv light)
(long/short identical)
(crystals)
(crystals)
(001h) (001fa) (001fb) (001fc)

(crystals)
(crystals)
  (001j)  
   
Atomic King Mine, Cane Creek Canyon,
Grand County, Utah, USA

Specimen Notes

Most of the Andersonite is in the form of crusts in fractures in the host rock. Images -001ia, -001ib, -001fb and -001fc show the few locations where crystaline Andersonite is found on the specimen.

Andersonite is highly fluorescent under both long and short wave ultraviolet light, as can be seen in images -001ba (room light only) and -001bb (room & U.V. light), where the fluorescence is easily visable under room light. This fluorescence can be so strong that in the dark, the Andersonite can illuminate the surrounding host rock.