kieseriet

Kieseriet, or kieserite, is a mineral species with the chemical formula MgSO4·H2O, making it the magnesium sulfate monohydrate. It forms as a hydrated evaporite mineral in arid or semi-arid environments where saline waters crystallize and often occurs in association with other evaporite minerals such as gypsum and anhydrite.

In appearance Kieseriet is typically colorless to white and can be transparent to translucent. Crystals, when present, are often prismatic or tabular, and the mineral commonly occurs as crystalline aggregates or as powdery, mass-forming material. It has a relatively low hardness on the Mohs scale and is soluble in water. The mineral is part of the broader family of magnesium sulfate minerals and shares common properties with related species such as epsomite (MgSO4·7H2O) and anhydrite.

The primary significance of kieseriet is its use as a source of magnesium and sulfur for agricultural purposes. As a fertilizer, kieserite supplies both magnesium, which is essential for plant growth, and sulfur, an important nutrient for many crops. The monohydrate form is noted for being less hygroscopic than the heptahydrate form (epsomite), which can make kieserite easier to store and handle in some applications. It is used in fertilization programs to correct magnesium deficiencies, particularly in calcareous soils or where sulfur-containing fertilizers are needed.

Distribution and occurrence are worldwide in evaporite basins, with deposits known from multiple regions. Kieseriet is thus an important mineral both scientifically and commercially due to its chemical composition and agricultural utility.