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.

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

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

This article about a specific sulfate mineral is a stub.