{{Short description|Mineral form of sodium bicarbonate}} {{Infobox mineral | name = Nahcolite | category = Carbonate mineral | boxwidth = | boxbgcolor = | image = Nahcolite-20212.jpg | imagesize = | alt = | caption = Nahcolite from California (size: 9.5 x 8 x 4 cm) | formula = Sodium bicarbonate (NaHCO<sub>3</sub>) | IMAsymbol = Nah<ref>{{Cite journal|last=Warr|first=L.N.|date=2021|title=IMA–CNMNC approved mineral symbols|journal=Mineralogical Magazine|volume=85|issue=3 |pages=291–320|doi=10.1180/mgm.2021.43 |bibcode=2021MinM...85..291W |s2cid=235729616 |doi-access=free}}</ref> | molweight = | strunz = 5.AA.15 | dana = 13.01.01.01 | system = Monoclinic | class = Prismatic (2/m) <br/><small>(same H-M symbol)</small> | symmetry = ''P''2<sub>1</sub>/n | unit cell = a = 7.47, b = 9.68 <br/>c = 3.48 [Å]; β = 93.38°; Z = 4 | color = | colour = White to colourless, may be grey to brown | habit = Elongated crystals, fibrous masses, friable porous aggregates | twinning = Common on [101] | cleavage = {101} perfect, {111} good, {100} distinct | fracture = Conchoidal | tenacity = Brittle | mohs = 2.5 | lustre = Vitreous – resinous | streak = White | diaphaneity = Transparent to translucent | gravity = 2.21 | density = | polish = | opticalprop = Biaxial (−) | refractive = n<sub>α</sub> = 1.377 n<sub>β</sub> = 1.503 n<sub>γ</sub> = 1.583 | birefringence = δ = 0.206 | pleochroism = | 2V = | dispersion = | extinction = | length fast/slow = | fluorescence= Short UV=blue-white cream-yellow, Long UV=cream-yellow | absorption = | melt = | fusibility = | diagnostic = | solubility = Soluble in water | other = | alteration = | references = <ref name=Mindat/><ref name=Handbook/><ref name=Webmin/> }} '''Nahcolite''' is a soft, colourless or white carbonate mineral with the composition of sodium bicarbonate (NaHCO<sub>3</sub>) also called '''thermokalite'''. It crystallizes in the monoclinic system.<ref name=Webmin/>
Nahcolite was first described in 1928 for an occurrence in a lava tunnel at Mount Vesuvius, Italy.<ref name=Mindat>[http://www.mindat.org/min-2831.html Nahcolite on Mindat.org]</ref> Its name refers to the elements which compose it: ''Na'', ''H'', ''C'', and ''O''.<ref>Richard V. Gaines, H. Catherine W. Skinner, Eugene E. Foord, Brian Mason, and Abraham Rosenzweig: Dana's new mineralogy, John Wiley & Sons, 1997</ref> It occurs as a hot spring and saline lake precipitate or efflorescence; in differentiated alkalic massifs; in fluid inclusions as a daughter mineral phase and in evaporite deposits.<ref name=Mindat/><Ref name=Webmin>[https://www.webmineral.com/data/Nahcolite.shtml Nahcolite data on Webmineral]</ref>
It occurs in association with trona, thermonatrite, thenardite, halite, gaylussite, burkeite, northupite and borax.<ref name=Handbook>{{Cite web |url=http://www.handbookofmineralogy.com/pdfs/nahcolite.pdf |title=Nahcolite in the Handbook of Mineralogy |access-date=2009-09-04 |archive-date=2020-10-23 |archive-url=https://web.archive.org/web/20201023211351/http://www.handbookofmineralogy.com/pdfs/nahcolite.pdf |url-status=dead }}</ref> It has been reported in a Roman conduit at Stufe de Nerone, Campi Flegrei, near Naples; in the United States from Searles Lake, San Bernardino County, California; in the Green River Formation, Colorado and Utah; in the Tincalayu deposit, Salar del Hombre Muerto, Salta Province, Argentina; on Mt. Alluaiv, Lovozero Massif and Khibiny Massif, Kola Peninsula, Russia; and around Mount Erebus, Victoria Land, Antarctica.<ref name=Handbook/> [[File:Nahcolite deposition model.png|thumb|left|400px|Nahcolite deposition model in the Uinta–Piceance basin system, United States]]
==References== {{Reflist}}
Category:Carbonate minerals Category:Sodium minerals Category:Monoclinic minerals Category:Minerals in space group 14 Category:Industrial minerals Category:Green River Formation Category:Sodium bicarbonate
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