Chemistry:Nahcolite

From HandWiki
Short description: Mineral form of sodium bicarbonate
Nahcolite
Nahcolite-20212.jpg
Nahcolite from California (size: 9.5 x 8 x 4 cm)
General
CategoryCarbonate mineral
Formula
(repeating unit)
Sodium bicarbonate (NaHCO3)
Strunz classification5.AA.15
Dana classification13.01.01.01
Crystal systemMonoclinic
Crystal classPrismatic (2/m)
(same H-M symbol)
Space groupP21/n
Unit cella = 7.47, b = 9.68
c = 3.48 [Å]; β = 93.38°; Z = 4
Identification
ColourWhite to colourless, may be grey to brown
Crystal habitElongated crystals, fibrous masses, friable porous aggregates
TwinningCommon on [101]
Cleavage{101} perfect, {111} good, {100} distinct
FractureConchoidal
TenacityBrittle
Mohs scale hardness2.5
Vitreous – resinous|re|er}}Vitreous – resinous
StreakWhite
DiaphaneityTransparent to translucent
Specific gravity2.21
Optical propertiesBiaxial (−)
Refractive indexnα = 1.377 nβ = 1.503 nγ = 1.583
Birefringenceδ = 0.206
Ultraviolet fluorescenceShort UV=blue-white cream-yellow, Long UV=cream-yellow
SolubilitySoluble in water
References[1][2][3]

Nahcolite is a soft, colourless or white carbonate mineral with the composition of sodium bicarbonate (NaHCO3) also called thermokalite. It crystallizes in the monoclinic system.[3]

Nahcolite was first described in 1928 for an occurrence in a lava tunnel at Mount Vesuvius, Italy.[1] Its name refers to the elements which compose it: Na, H, C, and O.[5] 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.[1][3]

It occurs in association with trona, thermonatrite, thenardite, halite, gaylussite, burkeite, northupite and borax.[2] It has been reported in a Roman conduit at Stufe de Nerone, Campi Flegrei, near Naples; in the U. S. 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.[2]

Nahcolite deposition model

References

  1. 1.0 1.1 1.2 Nahcolite on Mindat.org
  2. 2.0 2.1 2.2 Nahcolite in the Handbook of Mineralogy
  3. 3.0 3.1 3.2 Nahcolite data on Webmineral
  4. Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine 85 (3): 291–320. doi:10.1180/mgm.2021.43. Bibcode2021MinM...85..291W. https://www.cambridge.org/core/journals/mineralogical-magazine/article/imacnmnc-approved-mineral-symbols/62311F45ED37831D78603C6E6B25EE0A. 
  5. Richard V. Gaines, H. Catherine W. Skinner, Eugene E. Foord, Brian Mason, and Abraham Rosenzweig: Dana's new mineralogy, John Wiley & Sons, 1997