Borax - Occurrence, Properties, and Distribution

Borax is a mineral that was first discovered in the dry lake beds of Tibet. It was imported via the Silk Road to Arabia. The mineral was named after the Arabic word “bauraq”, which means white.

Properties of Borax

The following are the key properties of Borax:

  • Cell Data
    • Space Group: C2/c
    • a = 11.8790(2)
    • b = 10.6440(2)
    • c = 12.2012(2)
    • β = 106.617(1)°
    • Z = 4

  • Crystal Data
    • Monoclinic
    • Point Group: 2/m
    • Crystals are commonly short to long prismatic [001], and somewhat flattened on {100}, showing {100}, {110}, {001}, {112}, {111}, {010}, {021}, to 10cm, typically distorted; commonly massive.
    • Twinning: Rare on {100}
    • X-ray Powder Pattern: 2.576 (100), 2.565 (95), 4.86 (80), 2.848 (65), 2.833 (60), 5.69 (50), 3.936 (45)

  • Optical Properties
    • Optical Class: Biaxial (–)
    • Orientation: X = b; Z ^ c = –55°35'
    • Dispersion: r > v, strong, crossed
    • α = 1.4466
    • β = 1.4687
    • γ = 1.4717
    • 2V(meas.) = n.d
    • 2V(calc.) = 39°58'

  • Estimated Properties
    Electron density Bulk density (electron density)=1.78 g/cm3
    note: Specific gravity of Borax =1.71 g/cm3
    Photoelectric PEBorax = 0.47 barns/electron
    U= PEBorax x ρ Electron density= 0.84 barns/cm3
    Fermion index Fermion index = 0.02
    Boson index = 0.98
    Radioactivity
    Borax is not radioactive

How to Identify Borax

Borax is either colorless, or occurs in gray, gray-white, green, or blue color. It exhibits a translucent to opaque appearance, non-fluorescent characteristics, perfect cleavage, white streak, and greasy luster. It also possesses brittle fractures producing small, conchoidal fragments.

The mineral can be formed as uniformly indistinguishable crystals forming large masses, prismatic, or tabular structures.

The average density of borax is 1.71 g/cm3, and its hardness ranges from 2 to 2.5.

Global Distribution

Borax is distributed in the following places:

  • Ladakh district, Kashmir, to north of Lhasa, Tibet
  • Qinghai Province-Xizang Plateau, China
  • Kirka borate deposit, Kutahya Province, Turkey
  • Inder borate deposit, Kazakhstan
  • Loma Blanca deposit, 8km southwest of Coranzul´i, Jujuy Province, Argentina
  • Tincalayu borax deposit, Salar del Hombre Muerto, Salta Province, Argentina
  • Borax Lake, Lake Co. Searles Lake, San Bernardino Co. Kramer borate deposit, Boron, Kern Co. Furnace Creek and Resting Springs, Death Valley, Inyo Co. California
  • Rhodes Marsh, Teels Marsh, and others in Mineral Co. Nevada
  • Alkali Flat, Dona Ana Co. New Mexico

Occurrence of Borax and Useful Mineral Association

Borax occurs in evaporite deposits, salt lakes, playas, and is commonly well-crystallized. It also occurs as an efflorescence on soils in arid regions.

It is closely associated with gypsum, halite, hanksite, gaylussite, nitratine, calcite, glauberite, aphthitalite, trona, kurnakovite, kernite, colemanite, ulexite, and inyoite.

References

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