Blödite

Blödite or bloedite is a hydrated sodium magnesium sulfate mineral with formula: Na2Mg(SO4)2·4H2O. The mineral is clear to yellow in color often darkened by inclusions and forms monoclinic crystals.

Blödite
Doubly terminated blödite crystal from Soda Lake, San Luis Obispo County, California (size: 7.0 x 4.8 x 1.9 cm)
General
CategorySulfate minerals
Formula
(repeating unit)
Na2Mg(SO4)2·4H2O
IMA symbolBlö[1]
Strunz classification7.CC.50
Crystal systemMonoclinic
Crystal classPrismatic (2/m)
(same H-M symbol)
Space groupP21/a
Unit cella = 11.04 Å, b = 8.15 Å,
c = 5.49 Å; β = 100.41°; Z = 2
Identification
ColorColorless, yellow, may be dark gray, bluish green, or reddish due to inclusions
Crystal habitPrismatic to equant crystals, granular, massive
FractureConchoidal
TenacityBrittle
Mohs scale hardness2.5 - 3
LusterVitreous
Specific gravity2.23
Optical propertiesBiaxial (-)
Refractive indexnα = 1.483, nβ = 1.486, nγ = 1.487
Birefringenceδ = 0.004
2V angle71° (measured)
References[2][3][4]

Blödite was first described in 1821 for an occurrence in a salt deposit in Ischler Salzberg, Bad Ischl, Gmunden, Austria and named for German mineralogist and chemist Karl August Blöde (1773–1820).[3][4]

It is found worldwide in evaporitic sedimentary environments such as the Great Salt Lake, Utah.

See also

References

Crystal from Soda Lake (size: 2.9 x 2.2 x 1.4 cm)
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