Blödite

Blödite or bloedite is a hydrated sodium magnesium sulfate mineral with the 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 × 4.8 × 1.9 cm)
General
Category	Sulfate minerals
Formula	Na2Mg(SO4)2·4H2O
IMA symbol	Blö[1]
Strunz classification	7.CC.50
Crystal system	Monoclinic
Crystal class	Prismatic (2/m) (same H-M symbol)
Space group	P21/a
Unit cell	a = 11.04 Å, b = 8.15 Å, c = 5.49 Å; β = 100.41°; Z = 2
Identification
Color	Colorless, yellow, may be dark gray, bluish green, or reddish due to inclusions
Crystal habit	Prismatic to equant crystals, granular, massive
Fracture	Conchoidal
Tenacity	Brittle
Mohs scale hardness	2.5–3
Luster	Vitreous
Specific gravity	2.23
Optical properties	Biaxial (−)
Refractive index	nα = 1.483, nβ = 1.486, nγ = 1.487
Birefringence	δ = 0.004
2V angle	71° (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

• List of minerals
• List of minerals named after people