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

, NaNO₃. Chemically it is the sodium analogue of

saltpeter Potassium nitrate is a chemical compound with the chemical formula . This alkali metal nitrate salt is also known as Indian saltpetre (large deposits of which were historically mined in India). It is an ionic salt of potassium ions K+ and nitra ...

. Nitratine crystallizes in the trigonal system, but rarely occurs as well formed crystals. It is isostructural with

calcite Calcite is a carbonate mineral and the most stable polymorph of calcium carbonate (CaCO3). It is a very common mineral, particularly as a component of limestone. Calcite defines hardness 3 on the Mohs scale of mineral hardness, based on scratc ...

. It is quite 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 various minerals through the ability of harder material to scratch softer material. The scale was introduced in 1812 by ...

of 1.5 to 2 and a specific gravity of 2.24 to 2.29. Its

refractive indices In optics, the refractive index (or refraction index) of an optical medium is a dimensionless number that gives the indication of the light bending ability of that medium. The refractive index determines how much the path of light is bent, or ...

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 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 or adsorption from the surrounding environment, which is usually at normal or room temperature. If water molecules become suspended among the substance ...

and will absorb water out of the air and turn into a ''puddle'' of sodium nitrate solution when exposed to humid air. Nitratine was once an important source of nitrates for fertilizer and other chemical uses including fireworks. It has been known since 1845 from occurrences in the

Confidence Hills The Confidence Hills are a mountain range in the Mojave Desert, in southern Inyo County, California California is a state in the Western United States, located along the Pacific Coast. With nearly 39.2million residents across a total area ...

, Southern

Death Valley Death Valley is a desert valley in Eastern California, in the northern Mojave Desert, bordering the Great Basin Desert. During summer, it is the hottest place on Earth. Death Valley's Badwater Basin is the point of lowest elevation in Nort ...

, California and the

Atacama Desert The Atacama Desert ( es, Desierto de Atacama) is a desert plateau in South America covering a 1,600 km (990 mi) strip of land on the Pacific coast, west of the Andes Mountains. The Atacama Desert is the driest nonpolar desert in the w ...

Chile Chile, officially the Republic of Chile, is a country in the western part of South America. It is the southernmost country in the world, and the closest to Antarctica, occupying a long and narrow strip of land between the Andes to the east a ...

. It is still used in organic farming (where Haber–Bosch ammonia is forbidden) in the US, but prohibited in international organic agriculture. The Saltpeter War (1480-1510) and the War of the Pacific (1879-1884) were fought over the control of saltpeter deposits.

References

External links

Nitratine page
on

mindat.org Mindat.org is a non-commercial online database, claiming to be the largest mineral database and mineralogical reference website on the Internet. It is used by professional mineralogists, geologists, and amateur mineral collectors alike. The ...

Nitratine page on webmineral.com

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

See also

References

External links