carnallite

Carnallite is a hydrated potassium magnesium chloride mineral with the chemical formula KMgCl3·6H2O. It is a halide mineral that forms in evaporite deposits and is an important source of potassium. The mineral typically forms colorless to white crystals with a vitreous luster and a relatively soft Mohs hardness of about 2.5 to 3. It is highly soluble in water and can be found in substantial evaporite sequences.

Formation and occurrence: Carnallite forms by the evaporation of saline waters in sedimentary basins. It commonly occurs in association with sylvite (KCl) and halite (NaCl) within potash-bearing deposits and is one of several minerals mined for potash production. The mineral is widespread in evaporite regions and is exploited where potash ore concentrations are economically accessible.

Economic significance and processing: The primary economic role of carnallite is as an ore of potassium for fertilizer production. In potash operations, carnallite is processed to yield potassium chloride (KCl) and magnesium chloride, with additional potassic products derived through refining. Mining methods include underground extraction and solution mining in salt-bearing formations, where brines are pumped and refined to recover the desired components.

Additional notes: Carnallite is typically restricted to evaporite environments and must be handled in processing facilities to manage its high solubility and hydration state. As with many soluble salts, processing and transport require careful brine management and quality control to obtain consistent potash products.