Langbeinite

Langbeinite is a mineral species in the sulfate group with the chemical formula K2Mg2(SO4)3. It is a double sulfate containing potassium and magnesium as cations balanced by sulfate groups. Langbeinite occurs in evaporitic environments where saline waters have concentrated, and is typically associated with other sulfates such as gypsum, anhydrite, and kieserite. It forms crystals that are usually transparent to pale-colored, often colorless, and commonly occur as prismatic crystals or granular to massive aggregates. The mineral has a vitreous to pearly luster and a relatively soft, readily weathering habit.

In commerce and agriculture, langbeinite is mined and processed as a source of both potassium and magnesium. As a fertilizer material, it provides potassium and magnesium in a single mineral and is used to address deficiencies of either nutrient in soils or to reduce the salinity impact of other potassium fertilizers. Compared with some other sulfate minerals, langbeinite can offer a balanced K-Mg-S supply and is valued where both K and Mg are needed.

Langbeinite is named for its distinct triple-sulfate composition, differentiating it from simpler sulfates. It is widely used in agriculture as a mined ore of K and Mg and is also of interest to mineral collectors where present in well-formed crystals.