Nitratine or nitratite, also known as cubic niter (UK: nitre), soda niter or Chile saltpeter (UK: Chile saltpetre), is a mineral, the naturally occurring form of sodium nitrate, NaNO3.

It is relatively soft and light with a Mohs hardness of 1.5 to 2 and a specific gravity of 2.24 to 2.29.

[4] The typical form is as coatings of white, grey to yellowish brown masses.

The rare crystals when found typically have the scalenohedral form of the calcite structure.

It is very soluble in water such that it is deliquescent and will absorb water out of the air and turn into a puddle of sodium nitrate solution when exposed to humid air.

There are nitratine deposits located in arid regions across the world such as in Chile, Mexico, Egypt, Peru, and South Africa.

[5] Chile is the only country to sell their deposits commercially as fertilizer.

[5] Nitratine happens to be isostructural to calcite, CaCO3, a widespread naturally occurring mineral, although nitratine dissolution and crystallization occur much faster than the same processes for calcite.

[6] The structural similarity makes nitratine a very useful mineral for laboratory experiments concerning pressure dissolution and other experiments such as serving as a proxy for the deformation and formation of calcite.

Nitratine was once an important source of nitrates for fertilizer and other chemical uses including fireworks.

It has been known since 1845 from mineral deposits in the Confidence Hills, Southern Death Valley, California and the Atacama Desert, Chile.

[9] The mineral also has a wide range of applications beyond being used as a fertilizer in agricultural practices.

[5] It is also used as a refining agent to remove air bubbles by the glass and enamel industries.

[5] Nitratine, other alkali nitrates, or nitrites also have applications for solar technology serving as a heat-transfer or heat-storage medium.

[5] Nitratine can also be used as a substitute for potassium nitrate in gunpowder.

[citation needed] After World War I the need for a more efficient production of fertilizer led to the production of synthetic nitratine which was much less costly in terms of production than the Shanks process used to refine chilean saltpeter.

[5] The method of production involved using tail gases from nitric acid plants in combination with sodium carbonate solution or sodium hydroxide solution.

[5] The following reactions show the chemistry necessary to produce sodium nitrates: