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. T ...
, NaNO
3. Chemically it is the sodium analogue of
saltpeter. Nitratine crystallizes in the
trigonal 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 quite soft and light with a
Mohs hardness of 1.5 to 2 and a
specific gravity of 2.24 to 2.29. Its
refractive indices 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
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 ...
structure. It is found only as an efflorescence in very dry environments. 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.
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, Southern
Death Valley,
California and the
Atacama Desert,
Chile. 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.
See also
*
Niter
*
List of Saltpeter works in Tarapacá and Antofagasta
*
Mining in Chile
*
Paradas method
The paradas method ( es, método de paradas, ''sistema de paradas'') was a process to extract nitrate from caliche by leaching. In this method caliche was boiled in water in large pans called "paradas". It was a firewood and labour-intensive proces ...
References
External links
Nitratine pageon
mindat.org
Mindat.org is a non-commercial online database, claiming to be the largest mineral database and mineralogy, mineralogical reference website on the Internet. It is used by professional mineralogists, geologists, and amateur mineral collecting, mi ...
Nitratine page on webmineral.com
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Sodium minerals
Nitrate minerals
Saltpeter works
Trigonal minerals
Minerals in space group 167