Dawsonite

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Dawsonite
Dawsonite-165134.jpg
Dawsonite from Mont Saint-Hilaire, Rouville RCM, Montérégie, Québec, Canada
General
CategoryCarbonate minerals
Formula
(repeating unit)
NaAlCO3(OH)2
Strunz classification5.BB.10
Dana classification16a.03.08.01
Crystal systemOrthorhombic
Crystal classDipyramidal (mmm)
H-M symbol: (2/m 2/m 2/m)
Space groupImam
Identification
Formula mass144.00 g/mol
Colorwhite
Crystal habitencrustations or radial
Cleavageperfect on {110}
Fractureuneven
Mohs scale hardness3
Lustervitreous
Streakwhite
Diaphaneitytransparent
Specific gravity2.436
Refractive indexnα = 1.466
nβ = 1.542
nγ = 1.596
Birefringenceδ = 0.130
2V angle77°
References[1][2]

Dawsonite is a mineral composed of sodium aluminium carbonate hydroxide, chemical formula NaAlCO3(OH)2. It crystallizes in the orthorhombic crystal system. It is not mined for ore. It was discovered in 1874 during the construction of the Redpath Museum in a feldspathic dike on the campus of McGill University on the Island of Montreal, Canada.[1] It is named after geologist Sir John William Dawson (1820–1899).[2]

The type material is preserved in the collection of the Redpath Museum.[1]

See also[edit]

References[edit]

  1. ^ a b c Dawsonite, MinDat.org, retrieved 2009-12-06.
  2. ^ a b Dawsonite, WebMineral.com, retrieved 2009-12-06.