Antarcticite - Occurrence, Properties, and Distribution

Antarcticite was named after its place of first occurrence – Antarctica. It is an uncommon calcium chloride hexahydrate mineral.

Properties of Antarcticite

The following are the key properties of antarcticite:

  • Cell Data
    • Space group: P321
    • a = 7.89–7.907
    • c = 3.95
    • Z = 1

  • Crystal Data
    • Hexagonal
    • As aggregates of acicular crystals, to 15cm, with poor terminations
    • X-ray powder pattern: 3.44 (24), 2.80 (23), 2.16 (23), 2.60 (22), 3.98 (18), 2.28 (13), 6.92 (9)

  • Chemical Composition
    Elements Content 1 Content 2 Content 3
    H2O+ 49.2 49.27 49.34
    Cl 32.7 33.14 32.37
    Ca 17.5 17.25 18.29
    Na 0.34 0.30 -
    Mg 0.41 0.015 -
    K 0.008 - -
    Si - 0.003 -
    Fe - 0.003
    Al - 0.002 -
    Total 100.1 99.98 100.00

  • Optical Properties
    • Optical class: Uniaxial (–)
    • ω = 1.550
    • ε = 1.490–1.500

  • Estimated Properties
    Electron density Bulk density (electron density) = 1.78 g/cm3
    note: Specific gravity of antarcticite = 1.71g/cm3
    Photoelectric PEAntarcticite = 4.31 barns/electron
    U=PEAntarcticite x ρ electron density= 7.67 barns/cm3
    Fermion index Fermion index = 0.00046
    Boson index = 0.99953
    Radioactivity
    Antarcticite is not radioactive

How to Identify Antarcticite

Antarcticite can be identified in the field by its colorless structure. Its transparent form has {0001} perfect, {1010} very good cleavage. This mineral has a vitreous luster, with white streak. The fracture on this mineral is brittle.

The density of antarcticite is 1.705 - 1.725 g/cm3, with a hardness of 2-3 - between gypsum and calcite.

Global Distribution

Antarcticite is distributed in the following places:

  • USA - At Bristol Dry Lake, San Bernardino Co. California
  • Bahamas - On North Andros Island
  • Antarctica - From Don Juan Pond, Wright Valley, and elsewhere around Mt. Erebus, Victoria Land
  • South Africa - From the Bushveld complex, on Driekop Farm, Transvaal

Occurrence of Antarcticite and Useful Mineral Association

Antarcticite occurs in a precipitate from highly saline brines under very arid conditions, and in stratified fresh to brackish salt water columns in onshore blue holes. It is also an abundant component of inclusions in quartz in a zoned mafic pegmatoid. It is often associated with minerals such as halite, gypsum, and celestine.

References

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