Editorial Feature

Nitratine – Occurrence, Properties and Distribution

Nitratine is the chemical Na analogue of niter. It is found in the form of efflorescence in hot, dry regions.

It is named after the Nitrogen content in the chemical composition, and it was discovered in 1821 in the Tarapaca region in Chile.

Properties of Nitratine

The key physical properties of Nitratine are as below:

  • Cell Data
    • Space Group =R3c
    • a = 5.070
    • c=16.829
    • Z = 6

  • Crystal Data
    • Hexagonal
    • Point Group: 3 2/m
    • Crystals: rare as rhombohedral crystals, {1011}, to 3mm, stalactitic, cotton-like, typically granular, or in massive incrustations
    • X-ray powder pattern: Synthetic
      3.03 (100), 2.311 (25), 2.81 (16), 1.898 (16), 2.53 (10), 2.125 (10), 1.880 (8)

  • Chemical Composition
    Elements Content 1
    Na 27.05
    Nitrogen 16.48
    Oxygen 56.47

  • Optical Properties
    • Transparent
    • Lustre: vitreous
    • Color: colorless to white; tinged reddish-brown, lemon-yellow, gray with impurities
    • Optical Class: Uniaxial (-)
  • Estimated Properties
    Electron density Bulk density (electron density) = 2.23 g/cm3
    note: Specific gravity of Nitratine = 2.26 g/cm3
    Photoelectric PENitratine = 0.67 barns/electron
    U = PENitratine x ρelectron density = 1.49 barns/cm3
    Fermion index Fermion index = 0.16
    Boson index = 0.84
    GRapi = 0 (Gamma Ray American Petroleum Institute Units)
    Nitratine is not radioactive

How to Identify Nitratine

The color of nitratine varies from colorless to white, with a reddish-brown tint, or lemon-yellow tint, or gray, due to impurities. Its tenacity is sectile, to a certain degree.

It exhibits a hardness of 1.5 to 2. It is soluble in water, tastes bitter, and is a pungent chemical. Its deliquescence is above 80%.

Global Distribution

Nitratine is a mineral that is found in a number of locations. Some of the main locations are as below:

  • Chile – from Tarapaca district and Antofagasta
  • Argentina – from Los Manos Cave, Santa Cruz Province
  • USA – from Death Valley; Inyo and San Bernardino Co. Calofornia; Niter Buttes, Neveda; Mesa Co. Colorado and Flagstaff Coconino Co. Arizona

Occurrence of Nitratine and Useful Mineral Association

Nitratine is mainly bedded in the deposits formed in playas, in caves, deposited from seeping groundwater, leaching nitrates from overlying rocks, especially in dry, cold environments.

Some of the minerals with which nitratine is associated are niter, gypsum, halite, mirabilite, and epsomite.


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