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Category Sulfate minerals
(repeating unit)
Strunz classification 7.CD.10
Crystal system Monoclinic
Crystal class Prismatic (2/m)
(same H-M symbol)
Space group P21/c
Formula mass 322.9 g/mol
Color Colorless, white, yellowish-white, greenish-white
Crystal habit Granular or well-formed coarse crystals
Twinning Interpenetration twinning on {001}; also on {100}
Cleavage {100} perfect, {001} poor, {010} poor
Fracture Conchoidal
Mohs scale hardness 1.5–2
Luster Vitreous
Streak White
Diaphaneity Transparent to translucent to opaque
Specific gravity 1.49
Optical properties Biaxial (–), 2V=75.93°
Refractive index nα = 1.396, nβ = 1.4103, nγ = 1.419
Birefringence δ = 0.023
Pleochroism none
Other characteristics Not radioactive, non-fluorescent
References [1][2][3]

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 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. Its name 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


  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. 

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