<p>Mighan Playa is a closed intracontinental basin located 15 km northeast of Arak city. The water level in the playa is affected by various sources such as the Sodium Sulfate Company wastewater, purified wastewater plant, groundwater, precipitation, and evaporation. Mighan Playa consists of an island in the center and a lake in the periphery, and it is the most important pole of sodium sulfate extraction in Iran. Twenty-five samples were taken from the playa to evaluate the brine. The parameters EC, TH, pH, Ca²⁺, Mg²⁺, K⁺, Na⁺, Cl⁻, SO₄²⁻, Br⁻, I⁻, Li⁺, HCO₃⁻, NO₃⁻ and PO₄³⁻ were determined in the brine. The brine showed the ratio of HCO₃⁻to be greater than Ca²⁺ + Mg²⁺ and the geochemical evolution of the brine followed the proposed classification. The type of brine is (K⁺ + Na⁺)—Cl⁻- SO₄²⁻ in Mighan Playa. The brine at Mighan Playa has the possibility of forming evaporites such as glauberite, mirabilite, thenardite, halite, gypsum, calcite, and to a small extent, dolomite and anhydrite based on the saturation indexes. Important mineralization factors were identified by factor analysis and factorial fuzzy maps. The salinity of Mighan Playa brines is related to anions and cations originating from the gypsum and salt layers in the northern part of the playa watershed, while bicarbonate is derived from the dissolution of limestone rocks in the southern layers of the Mighan watershed.</p>