Langbeinite

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Langbeinite
General
Category Sulfate mineral
Formula
(repeating unit)
K2Mg2(SO4)3
Strunz classification 07.AC.10
Crystal symmetry Isometric tetartoidal
H-M symbol: (2 3)
Space group: P 213
Unit cell a = 9.92 Å; Z=4
Identification
Color Colorless with pale shades of yellow, pink, red, green, gray
Crystal habit As nodules, disseminated grains, bedded massive
Crystal system Cubic
Fracture Conchoidal
Tenacity Brittle
Mohs scale hardness 3.5 - 4
Luster Vitreous
Diaphaneity Transparent
Specific gravity 2.83
Optical properties Isotropic
Refractive index n = 1.5329–1.5347
Solubility Slowly dissolves in water
Other characteristics Piezoelectric
References [1][2][3]

Langbeinite is a potassium magnesium sulfate mineral with formula: K2Mg2(SO4)3. Langbeinite crystallizes in the isometric - tetartoidal system as transparent colorless or white with pale tints of yellow to green and violet crystalline masses. It has a vitreous luster. The Mohs hardness is 3.5 to 4 and the specific gravity is 2.83. The crystals are piezoelectric.[1]

The mineral is an ore of potassium and occurs in marine evaporite deposits in association with carnallite, halite and sylvite.[1]

It was first described in 1891 for an occurrence in Wilhelmshall, Halberstadt, Saxony-Anhalt, Germany, and named for A. Langbein of Leopoldshall, Germany.[1][2]

References[edit]