Langbeinite

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Langbeinite
Langbeinite-553833.jpg
General
CategorySulfate mineral
Formula
(repeating unit)
K2Mg2(SO4)3
IMA symbolLbn[1]
Strunz classification7.AC.10
Crystal systemCubic
Crystal classTetartoidal (23)
(same H-M symbol)
Space groupP213
Unit cella = 9.92 Å; Z = 4
Identification
ColorColorless with pale shades of yellow, pink, red, green, gray
Crystal habitAs nodules, disseminated grains, bedded massive
FractureConchoidal
TenacityBrittle
Mohs scale hardness3.5 - 4
LusterVitreous
DiaphaneityTransparent
Specific gravity2.83
Optical propertiesIsotropic
Refractive indexn = 1.5329–1.5347
Solubility280 g/L (20°C);[2] Slowly dissolves in water[3]
Other characteristicsPiezoelectric
References[4][5][6]

Langbeinite is a potassium magnesium sulfate mineral with the chemical formula K2Mg2(SO4)3. Langbeinite crystallizes in the isometric-tetartoidal (cubic) 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.[4]

The mineral is an ore of potassium and occurs in marine evaporite deposits in association with carnallite, halite, and sylvite.[4]

It was first described in 1891 for an occurrence in Wilhelmshall, Halberstadt, Saxony-Anhalt, Germany, and named for A. Langbein of Leopoldshall, Germany.[4][5]

Langbeinite gives its name to the langbeinites, a family of substances with the same cubic structure, a tetrahedral anion, and large and small cations.

Related substances include hydrated salts leonite (K2Mg(SO4)2·4H2O) and picromerite (K2Mg(SO4)2·6H2O).

References[edit]

  1. ^ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.
  2. ^ Artiola, Janick F.; Gebrekidan, Heluf; Carty, David J. (October 2000). "Use of langbeinite to reclaim sodic and saline sodic soils". Communications in Soil Science and Plant Analysis. 31 (17–18): 2829–2842. doi:10.1080/00103620009370631. S2CID 95055306.
  3. ^ Harley, G. T.; Atwood, G. E. (January 1947). "Langbeinite... Mining and processing". Industrial & Engineering Chemistry. 39 (1): 43–47. doi:10.1021/ie50445a020.
  4. ^ a b c d Handbook of Mineralogy
  5. ^ a b Mindat with location data
  6. ^ Webmineral data