Billietite - Occurrence, Properties, and Distribution

Billietite was named after Valere Louis Billiet (1903–1945), a Belgian crystallographer associated with the University of Ghent in Ghent, Belgium.

It is an uncommon mineral of Uranium that contains Barium.

Properties of Billietite

The following are the key properties of billietite:

  • Cell Data
    • Space group: Pbn21
    • a = 12.0720(22)
    • b = 30.167(4)
    • c = 7.1455(5)
    • Z = 4

  • Crystal Data
    • Orthorhombic
    • Point group: mm2
    • Crystals: pseudohexagonal, tabular on {001}, may be elongated along [110], to 5mm
    • Twinning: Very common, on {110} and {111}, the latter producing sector-twinned aragonite-like groups
    • X-ray powder pattern: 7.53 (10), 3.77 (9), 3.17 (8), 2.03 (6), 3.54 (5), 2.49 (4), 2.56 (3)

  • Chemical Composition
Elements Content 1 Content 2 Content 3
UO3 82.76 84.39 86.00
H2O 8.97 8.68 6.32
BaO 6.88 7.41 7.68
SiO2 0.76 - -
CaO 0.30 - -
Total - - -

  • Optical Properties
    • Optical class: Biaxial (-)
    • Pleochroism: Distinct; X = colorless to pale yellow; Y = Z = greenish-yellow to deep golden-yellow, amber-brown
    • Orientation: X = c; Y = a; Z = b
    • Dispersion: r > v, very strong
    • α = 1.725–1.730; β = 1.780–1.822; γ = 1.790–1.829
    • 2V(meas.) = ∼36°

  • Estimated Properties
Electron density Bulk density (electron density) = 4.44 g/cm3
note: Specific gravity of billietite = 5.28 g/cm3
Photoelectric PE Billietite = 1,893.82 barns/electron
U = PE Billietite x ρ electron density = 8,414.80 barns/cm3
Fermion index Fermion index = 0.01
Boson index = 0.99
Radioactivity Billietite is radioactive

How to Identify Billietite

Billietite can be identified in the field by its color variations, such as yellow-brown and golden-yellow. Its transparent to translucent form has {001} perfect cleavage. This mineral has an adamantine luster, with yellow streak.

The density of billietite is 5.27 to 5.29 g/cm3.

Global Distribution

Billietite is distributed in the following places:

  • Congo - From Shinkolobwe and in the Musonoi mine, near Kolwezi, Katanga Province
  • France - From the La Crouzille mine, and the Margnac mine, Compreignac, Haute-Vienne, and in the Rabejac uranium deposit, 7km south-south-east of Lodeve, Herault
  • Germany - At Wolsendorf, Bavaria; from Menzenschwand
  • Wittichen, Black Forest; and at Bergen, Vogtland, Saxony
  • USA - On Mauch Chunk Ridge, Jim Thorpe, Carbon Co. Pennsylvania, and in the Delta mine, Emery Co. Utah

Occurrence of Billietite and Useful Mineral Association

Billietite occurs in an uncommon alteration product of uraninite.

It is often associated with minerals such as uranophane, metatorbernite, rutherfordine, fourmarierite, becquerelite, soddyite, and studtite.

References

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