Nahcolite

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Nahcolite
General
CategoryMineral
Chemical formulaNaHCO3
Strunz classification05.AA.15
Dana classification13.01.01.01
Identification
ColourWhite to colourless, may be grey to brown
Crystal habitElongated crystals, fibrous masses, friable porous aggregates
Crystal systemMonoclinic prismatic
TwinningCommon on [101]
Cleavage{101} perfect, {111} good, {100} distinct
FractureConchoidal
TenacityBrittle
Mohs scale hardness2.5
LusterVitreous - 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
References[1][2][3]
 
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Nahcolite
General
CategoryMineral
Chemical formulaNaHCO3
Strunz classification05.AA.15
Dana classification13.01.01.01
Identification
ColourWhite to colourless, may be grey to brown
Crystal habitElongated crystals, fibrous masses, friable porous aggregates
Crystal systemMonoclinic prismatic
TwinningCommon on [101]
Cleavage{101} perfect, {111} good, {100} distinct
FractureConchoidal
TenacityBrittle
Mohs scale hardness2.5
LusterVitreous - 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
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] The name is in reference to its chemical formula. 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] Its name refers to the elements which compose it: Na, H, C, and O.[4]

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]

References

  1. ^ a b c Mindat Data sheet
  2. ^ a b c http://www.handbookofmineralogy.com/pdfs/nahcolite.pdf Handbook of Mineralogy
  3. ^ a b c http://www.webmineral.com/data/Nahcolite.shtml Webmineral data
  4. ^ Richard V. Gaines, H. Catherine W. Skinner, Eugene E. Foord, Brian Mason, and Abraham Rosenzweig: Dana's new mineralogy, John Wiley & Sons, 1997