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Mirabilite, also known as Glauber's salt, is a hydrous sodium sulfate mineral with the chemical formula Na2SO4·10H2O. It is a vitreous, colorless to white monoclinic mineral that forms as an evaporite from sodium sulfate-bearing brines. It is found around saline springs and along saline playa lakes. Associated minerals include gypsum, halite, thenardite, trona, glauberite, and epsomite.

Mirabilite
Mangxiao.jpg
General
CategorySulfate minerals
Formula
(repeating unit)
Na2SO4·10H2O
Strunz classification7.CD.10
Crystal systemMonoclinic
Crystal classPrismatic (2/m)
(same H-M symbol)
Space groupP21/c
Identification
Formula mass322.9 g/mol
ColorColorless, white, yellowish-white, greenish-white
Crystal habitGranular or well-formed coarse crystals
TwinningInterpenetration twinning on {001}; also on {100}
Cleavage{100} perfect, {001} poor, {010} poor
FractureConchoidal
Mohs scale hardness1.5–2
LusterVitreous
StreakWhite
DiaphaneityTransparent to translucent to opaque
Specific gravity1.49
Optical propertiesBiaxial (–), 2V=75.93°
Refractive indexnα = 1.396, nβ = 1.4103, nγ = 1.419
Birefringenceδ = 0.023
Pleochroismnone
Other characteristicsNot radioactive, non-fluorescent
References[1][2][3]

Mirabilite is unstable and quickly dehydrates in dry air, the prismatic crystals turning into a white powder, thenardite (Na2SO4). In turn, thenardite can also absorb water and converts to mirabilite.

Mirabilite is used as a purgative in the Traditional Chinese medicine; in Mandarin, it is called máng xiāo. The name 'mirabilite' is based on the phrase "Sal mirabilis" (Latin for "wonderful salt") used by Johann Rudolph Glauber when he inadvertently synthesized mirabilite.[3][4]

Crystal structure of mirabilite

ReferencesEdit

  1. ^ Mineralienatlas
  2. ^ Mirabilite at Webmineral
  3. ^ a b Mirabilite at Mindat
  4. ^ Hill, James C. (1979). "Johann Glauber's discovery of sodium sulfate - Sal Mirabile Glauberi". Journal of Chemical Education. 56 (9): 593. Bibcode:1979JChEd..56..593H. doi:10.1021/ed056p593.

External linksEdit