Nitratine or nitratite, also known as cubic niter (UK: nitre), soda niter or Chile saltpeter (UK: Chile saltpetre), is a

mineral In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid substance with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.John P. Rafferty, ed. (2011): Mi ...

, the naturally occurring form of

sodium nitrate Sodium nitrate is the chemical compound with the chemical formula, formula . This alkali metal nitrate salt (chemistry), salt is also known as Chile saltpeter (large deposits of which were historically mined in Chile) to distinguish it from ordi ...

, NaNO₃. Chemically it is the sodium analogue of

saltpeter Potassium nitrate is a chemical compound with a sharp, salty, bitter taste and the chemical formula . It is a potassium salt of nitric acid. This salt consists of potassium cations and nitrate anions , and is therefore an alkali metal nitrate ...

. Nitratine crystallizes in the

trigonal In crystallography, the hexagonal crystal family is one of the six crystal family, crystal families, which includes two crystal systems (hexagonal and trigonal) and two lattice systems (hexagonal and rhombohedral). While commonly confused, the tr ...

system, but rarely occurs as well-formed crystals. It is isostructural with

calcite Calcite is a Carbonate minerals, carbonate mineral and the most stable Polymorphism (materials science), polymorph of calcium carbonate (CaCO3). It is a very common mineral, particularly as a component of limestone. Calcite defines hardness 3 on ...

. It is relatively soft and light with a

Mohs hardness The Mohs scale ( ) of mineral hardness is a qualitative ordinal scale, from 1 to 10, characterizing scratch resistance of mineral In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid substance with a fair ...

of 1.5 to 2 and a

specific gravity Relative density, also called specific gravity, is a dimensionless quantity defined as the ratio of the density (mass of a unit volume) of a substance to the density of a given reference material. Specific gravity for solids and liquids is nea ...

of 2.24 to 2.29. Its

refractive indices In optics, the refractive index (or refraction index) of an optical medium is the ratio of the apparent speed of light in the air or vacuum to the speed in the medium. The refractive index determines how much the path of light is bent, or refrac ...

are nω = 1.587 and nε = 1.336. 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

structure. It is found only as an

efflorescence In chemistry, efflorescence (Derived from the Latin verb 'efflorescere' roughly meaning 'to flower') is the migration of a salt to the surface of a porous material, where it forms a coating. The essential process involves the dissolving of an i ...

in very dry environments. It is very soluble in water such that it is

deliquescent Hygroscopy is the phenomenon of attracting and holding water molecules via either absorption (chemistry), absorption or adsorption from the surrounding Natural environment, environment, which is usually at normal or room temperature. If water mol ...

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. Chile is the only country to sell their deposits commercially as fertilizer. The salt bed that is mined contains more minerals than just nitratine often containing sulfurous minerals as well as Iodine. Around 600,000 tons of nitratine are mined in Chile each year with other products such as Iodine and sodium sulfate mined as well. Nitratine happens to be isostructural to calcite, CaCO₃, a widespread naturally occurring mineral, although nitratine dissolution and

crystallization Crystallization is a process that leads to solids with highly organized Atom, atoms or Molecule, molecules, i.e. a crystal. The ordered nature of a crystalline solid can be contrasted with amorphous solids in which atoms or molecules lack regu ...

occur much faster than the same processes for calcite. 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. The Saltpeter War (1480–1510) and the

War of the Pacific The War of the Pacific (), also known by War of the Pacific#Etymology, multiple other names, was a war between Chile and a Treaty of Defensive Alliance (Bolivia–Peru), Bolivian–Peruvian alliance from 1879 to 1884. Fought over Atacama Desert ...

(1879–1884) were fought over the control of saltpeter deposits.

Uses

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

fireworks Fireworks are Explosive, low explosive Pyrotechnics, pyrotechnic devices used for aesthetic and entertainment purposes. They are most commonly used in fireworks displays (also called a fireworks show or pyrotechnics), combining a large numbe ...

. It has been known since 1845 from mineral deposits in the

Confidence Hills The Confidence Hills are a mountain range in the Mojave Desert, in southern Inyo County, California, Inyo County, California. They are known as Confidence Hills for their formation of favorable flower structures, which are developed in Pliocene ...

, Southern

Death Valley Death Valley is a desert valley in Eastern California, in the northern Mojave Desert, bordering the Great Basin Desert. It is thought to be the Highest temperature recorded on Earth, hottest place on Earth during summer. Death Valley's Badwat ...

California California () is a U.S. state, state in the Western United States that lies on the West Coast of the United States, Pacific Coast. It borders Oregon to the north, Nevada and Arizona to the east, and shares Mexico–United States border, an ...

and the

Atacama Desert The Atacama Desert () is a desert plateau located on the Pacific Ocean, Pacific coast of South America, in the north of Chile. Stretching over a strip of land west of the Andes Mountains, it covers an area of , which increases to if the barre ...

Chile Chile, officially the Republic of Chile, is a country in western South America. It is the southernmost country in the world and the closest to Antarctica, stretching along a narrow strip of land between the Andes, Andes Mountains and the Paci ...

. It is still used in

organic farming Organic farming, also known as organic agriculture or ecological farming or biological farming,Labelling, article 30 o''Regulation (EU) 2018/848 of the European Parliament and of the Council of 30 May 2024 on organic production and labelling of ...

(where Haber–Bosch ammonia is forbidden) in the US, but prohibited in international

organic agriculture Organic farming, also known as organic agriculture or ecological farming or biological farming,Labelling, article 30 o''Regulation (EU) 2018/848 of the European Parliament and of the Council of 30 May 2024 on organic production and labelling of ...

.'' The Omnivores Dilemma'' – Michael Pollan The mineral also has a wide range of applications beyond being used as a fertilizer in agricultural practices. Nitratine has been used in the

explosives An explosive (or explosive material) is a reactive substance that contains a great amount of potential energy that can produce an explosion if released suddenly, usually accompanied by the production of light, heat, sound, and pressure. An exp ...

industry for water-containing slurry as well as gel explosives. It is also used as a refining agent to remove air bubbles by the glass and enamel industries. Nitratine, other alkali nitrates, or nitrites also have applications for solar technology serving as a heat-transfer or heat-storage medium. Nitratine can also be used as a substitute for potassium nitrate in gunpowder.

Synthetic sodium nitrate

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. The method of production involved using tail gases from nitric acid plants in combination with sodium carbonate solution or sodium hydroxide solution. Through a series of reactions it is possible to produce sodium nitrate and sodium nitrate with byproducts such as nitrogen monoxide and water. The following reactions show the chemistry necessary to produce sodium nitrates: 2NaOH + 2NO2 + NO -> 2NaNO2 + H2O Na2CO3 + NO2 + NO -> 2NaNO2 +CO2 2NaOH + 2NO2 -> NaNO3 + NaNO2 + H2O Na2CO3 + 2NO2 -> NaNO3 + NaNO2 +CO2 3NaNO2 + 2HNO3 -> 3NaNO3 + 2 NO + H2O La Palma Santa Cruz Nitrato de Chile R01

La Palma Santa Cruz Nitrato de Chile R01

References

External links

Nitratine page
on

mindat.org Mindat.org is a non-commercial interactive online database covering minerals around the world. Originally created by Jolyon Ralph as a private project in 1993, it was launched as a community-editable website in October 2000. it is operated by ...

Nitratine page on webmineral.com

{{Authority control Sodium minerals Nitrate minerals Saltpeter works Trigonal minerals Minerals in space group 167

Uses

Synthetic sodium nitrate

See also

References

External links