Nitratine Locality: La Penma, Antofagasta Region, Chile Original description: An 8.1 by 6.1 cms mass small white crystals covered by a light brown clay. The loc — Photo: John Sobolewski (JSS) · CC BY 3.0
Nitratine
Also known as: Chile saltpeter, Soda niter.
Natural sodium nitrate — 'Chile saltpeter' — the soluble mineral mined in the Atacama for fertilizer.
Intro adapted from Wikipedia (CC BY-SA).
Nitratine is an IMA-recognized mineral species in the nitrate class, with the chemical formula Na(NO₃).
It crystallizes in the hexagonal crystal system (space group R-3c). It is a member of the Calcite structural group.
Key properties: Mohs hardness 1.5–2; specific gravity 2.24–2.29; typically colorless or white or gray or brown; white streak; Vitreous luster; refractive index 1.464; optically uniaxial.
IMA symbol Ntt, IMA status: approved, named in 1845.
Principally in bedded deposits formed in playas; in caves, deposited from seeping groundwater leaching nitrates from overlying rocks, especially in very dry and cold climates.
It is found associated with Niter, nitrocalcite, epsomite, mirabilite, halite, gypsum.
The name refers to NITRogen in the composition.
Collections: Everyday Minerals.