Bazzite – Occurrence, Properties, and Distribution

Bazzite is named after Alessandro E. Bazzi, who discovered this mineral in Baveno, Italy in 1915. This mineral belongs to the Beryl group as it mostly occurs as deep blue or blue-green color small hexagonal crystals.

Properties of Bazzite

The following are the key properties of bazzite:

  • Cell Data
    • Space group: P6/mcc
    • a = 9.521(5)
    • c = 9.165(5)
    • Z = 2
  • Crystal Data
    • Hexagonal
    • Point group: 6/m 2/m 2/m
    • Hexagonal prisms, to 2 cm
    • Barrel-like and in sub-parallel aggregation
    • X-ray powder pattern: Synthetic Be3 (Sc 1:75 Fe3+0:25) Σ=2:00 Si6O18.
    • 3.306 (100), 8.27 (89), 2.960 (75), 4.006 (48), 4.578 (24), 2.577 (17), 1.761 (15)
  • Chemical Composition
    Elements Content 1 Content 2
    SiO2 58.8 58
    Sc2O3 14.44 14.5
    BeO 12.9 14.5
    FeO 3.68 -
    Fe2O3 2.21 5.7
    Na2O 2.82 1.6
    H2O+ 2.6 1.1
    MnO 1.58 1.43
    Al2O3 0.25 0.8
    MgO 0.82 0.1
    Cs2O 0.31 2.93
    Li2O 0 0.24
    K2O 0.22 0.13
    Rb2O 0.037 0.25
    Total 100.67 101.28
  • Optical Properties
    • Optical class: Uniaxial (-)
    • Pleochroism: O = pale greenish yellow; E = dark sky-blue
    • ω = 1.622-1.637
    • ε = 1.602-1.622
  • Estimated Properties
    Electron density Bulk density (electron density) = 2.76 gm/cm3
    note: Specific gravity of bazzite = 2.80 gm/cm3
    Photoelectric PEBazzite = 2.93 barns/electron
    U = PEBazzite x ρelectron density = 8.09 barns/cm3
    Fermion index Fermion index = 0.06
    Boson index = 0.94

    Radioactivity

    Bazzite is not radioactive.

How to Identify Bazzite

Bazzite is identified in the field by its light blue and dark blue variations with indistinct cleavages and brittle fracture. This mineral occurs as symmetrical fine-sized crystals that are formed in the shape of thin prisms. It is semi-transparent with a glassy lustre and a light bluish white streak but without fluorescence. The density of bazzite is 2.8 gm/cm3 with a hardness of 6.5 (approximate to pyrite).

Global Distribution

Bazzite is found in many locations around the world. Some of the key locations are listed below:

  • Italy - Baveno, Piedmont.
  • Switzerland -Val Strem, Graubunden, Witenalp, Wiler-Reusstal, Stollen Oberaar, Grimsel Pass.
  • Austria - Heiligenblut, Carinthia.
  • Norway -Large crystals from Heftetjern, Tordal.
  • USA - Mt. Antero and Mt.White, Chaffee Co., Colorado.

Occurrence of Bazzite and Useful Mineral Association

In the past, bazzite has occurred in the miarolitic cavities in granite in Baveno, Italy, in the alpine veins of Switzerland, and in granite pegmatite in Heftetjern, Norway. It is often associated with minerals such as quartz, muscovite, laumontite, orthoclase, albite, hematite, albite, calcite, beryl, chlorite, fluorite, and bavenite.

References

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