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Niter or nitre<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> is the mineral form of potassium nitrate, KNO3. It is a soft, white, highly soluble mineral found primarily in arid climates or cave deposits.
Potassium and other nitrates are of great importance for use in fertilizers and, historically, gunpowder. Much of the world's demand is now met by synthetically produced nitrates, though the natural mineral is still mined and is still of significant commercial value.<ref>Template:Cite journal</ref><ref>Template:Cite journal</ref>
Historically, the term niter was not well differentiated from natron, both of which have been very vaguely defined but generally refer to compounds of sodium or potassium joined with carbonate or nitrate ions.
CharacteristicsEdit
Niter is a colorless to white mineral crystallizing in the orthorhombic crystal system. It is the mineral form of potassium nitrate, Template:Chem2,<ref name=Jackson/> and is soft (Mohs hardness 2),<ref name="HoM"/> highly soluble in water,<ref name=Jackson>Template:Cite book</ref> and easily fusible. Its crystal structure resembles that of aragonite, with potassium replacing calcium and nitrate replacing carbonate.<ref>Template:Cite book</ref> It occurs in the soils of arid regions and as massive encrustations and efflorescent growths on cavern walls and ceilings where solutions containing alkali potassium and nitrate seep into the openings.<ref name=Jackson/> It occasionally occurs as prismatic acicular crystal groups, and individual crystals commonly show pseudohexagonal twinning on [110]. Niter and other nitrates can also form in association with deposits of guano and similar organic materials.<ref name="HoM">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>
History and etymologyEdit
Niter as a term has been known since ancient times, although there is much historical confusion with natron (an impure sodium carbonate/bicarbonate), and not all of the ancient salts known by this name or similar names in the ancient world contained nitrate.<ref name=Jackson/> The name is from the Ancient Greek {{#invoke:Lang|lang}} {{#invoke:Lang|lang}} from Ancient Egyptian {{#invoke:Lang|lang}}, related to the Hebrew {{#invoke:Lang|lang}}, for salt-derived ashes (their interrelationship is not clear).<ref name="oed">Template:Oed</ref>
The Hebrew {{#invoke:Lang|lang}} may have been used as, or in conjunction, with soap, as implied by Jeremiah 2:22, "For though thou wash thee with niter, and take thee much soap..." However, it is not certain which substance (or substances) the Biblical "neter" refers to, with some suggesting sodium carbonate.<ref>Template:Cite journal</ref>
The Neo-Latin word for sodium, {{#invoke:Lang|lang}}, is derived from this same class of desert minerals called {{#invoke:Lang|lang}} (French)<ref>Template:Oed</ref> through Spanish {{#invoke:Lang|lang}} from Greek {{#invoke:Lang|lang}} ({{#invoke:Lang|lang}}), derived from Ancient Egyptian {{#invoke:Lang|lang}}, referring to the sodium carbonate salts occurring in the deserts of Egypt, not the nitratine (nitrated sodium salts) typically occurring in the deserts of Chile (classically known as "Chilean saltpeter" and variants of this term).<ref name="oed"/><ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>Template:Self-published inline
A term ({{#invoke:Lang|lang}}, {{#invoke:Lang|lang}} or aphronitre) which translates as "foam of niter" was a regular purchase in a fourth-century AD series of financial accounts, and since it was expressed as being "for the baths" was probably used as soap.<ref>More conventional soap also appears in the accounts but was more expensive: John Matthews, The Journey of Theophanes, Yale UP 2006</ref>
Niter was used to refer specifically to nitrated salts known as various types of saltpeter (only nitrated salts were good for making gunpowder) by the time niter and its derivative nitric acid were first used to name the element nitrogen, in 1790.<ref>Template:Oed</ref>
AvailabilityEdit
Template:See also Because of its ready solubility in water, niter is most often found in arid environments and often in conjunction with other soluble minerals like halides, iodates, borates, gypsum, and rarer carbonates and sulphates.<ref>Template:Cite book</ref><ref>Template:Cite journal</ref>
Niter occurs naturally in certain places like the "Caves of Salnitre" (Collbató) known since the Neolithic. In the "Cova del Rat Penat", guano (bat excrements) deposited over thousands of years became saltpeter after being leached by the action of rainwater.Template:Citation needed
In 1783, Giuseppe Maria Giovene and Alberto Fortis together discovered a "natural nitrary" in a doline close to Molfetta, Italy, named Pulo di Molfetta. The two scientists discovered that niter formed inside the walls of the caves of the doline, under certain conditions of humidity and temperature.<ref>Template:Cite journal</ref> After the discovery, it was suggested that manure could be used for agriculture, in order to increase the production, rather than to make gunpowder.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> The discovery was challenged by scholars until chemist Giuseppe Vairo and his pupil Antonio Pitaro confirmed the discovery. Naturalists sent by academies from all Europe came in large number to visit the site; since niter is a fundamental ingredient in the production of gunpowder, these deposits were of considerable strategic interest.<ref name="Elogio">Template:Cite journal</ref>Template:Rp The government started extraction. Shortly thereafter, Giovene discovered niter in other caves of Apulia.<ref name="Elogio" />Template:Rp<ref>Template:Cite book</ref> The remnants of the extraction plant is a site of industrial archaeology, although currently not open to tourists.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}Template:Dead link</ref>
Similar mineralsEdit
Related minerals are soda niter (sodium nitrate), ammonia niter or gwihabaite (ammonium nitrate), nitrostrontianite (strontium nitrate), nitrocalcite (calcium nitrate), nitromagnesite (magnesium nitrate), nitrobarite (barium nitrate) and two copper nitrates, gerhardtite and buttgenbachite; in fact all of the natural elements in the first three columns of the periodic table and numerous other cations form nitrates which are uncommonly found for the reasons given, but have been described. Niter was used to refer specifically to nitrated salts known as various types of saltpeter (only nitrated salts were good for making gunpowder) by the time niter and its derivative nitric acid were first used to name the element nitrogen, in 1790.Template:Citation needed
See alsoEdit
- Template:Annotated link
- Nitratine - Sodium based fertilizer