Editorial Feature

Pinalite – Occurrence, Properties and Distribution

Pinalite is named after Pinal Co, Arizona, where it was discovered first. It was discovered in the year 1988.

Properties of Pinalite

The key physical properties of Pinalite are as below:

  • Cell Data
    • Space group: Amam
    • a = 11.073(2)
    • b=13.067 (3)
    • c=5.617 (1)
    • Z = 4
  • Crystal Data
    • Orthorhombic
    • Point group: 2/m 2/m 2/m
    • Crystals – as bladed acicular crystals, up to 0.5 mm elongated along [001], flattened on {010}, terminated by {h01}; in slightly divergent sprays.
    • Twinning – About [010], yielding penetration twins by rotation.
    • X-ray powder pattern: Mammoth St Antony Mine, Arizona, USA; 2.926 (10), 3.778 (9), 1.642 (5), 3.284 (4), 2.814 (4), 6.52 (3), 2.770 (3)
  • Chemical Composition
    Elements Content 1 Content 2
    WO3 23.3 24.24
    PbO 70.7 70.02
    Cl 7.1 7.41
    -O = Cl2 1.6 1.67
  • Optical Properties
    • Transparent
    • Optical class- Biaxial
    • Lustre - adamantine
  • Estimated Properties
    Electron density Bulk density (electron density)= 6.44 g/cm3
    note: Specific gravity of Pinalite = 7.82 g/cm3
    Photoelectric PEPinalite = 1463.24 barns/electron
    U=PEPinalite x ρelectron density= 9428.25 barns/cm3
    Fermion index Fermion index = 0.17
    Boson index = 0.83
    Radioactivity
     
    GRapi = 0 (Gamma Ray American Petroleum Institute Units)
    Pinalite is not radioactive

How to Identify Pinalite

Pinalite appears as a yellow mineral on field. It exhibits an adamantine lustre. It is brittle by nature and its density is 7.78.

Global Distribution

Pinalite is widely distributed in the following locations:

  • USA – Mammoth-St, Antony mine, Tiger, Pinal Co in Arizona.

Occurrence of Pinalite and Useful Mineral Association

Pinalite occurs as a late stage secondary mineral in the oxidized zone of base metal deposit. It is commonly associated with cerussite, caledonite, connellite, chromian leadhillite, quartz, iranite and murdochite.

References

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