Actual bloedite mineral precipitation in a seasonal lake in Çankırı-Çorum basin

Abstract

Bloedite (Na2Mg(SO4)2.4H2O) which is an economically important sodium sulfate mineral currently precipitates through evaporation in Lake İshakli, a small seasonal lake ( playa lake ) situated to the north of İshakli Village (Bayat - Çorum) in Çankırı-Çorum Basin. Lake İshaklı, in which actual bloedite precipitation has been determined for the first time by this work in Turkey, extends in East-West direction and covers an area of approximately 220.000 m2 . During winter and spring months it becomes a lake with a depth of more than 2 m. However, during hot periods when evaporation becomes effective, the lake dries up and is covered with a white mineral crust. Mineralogical determinations, chemical analyses and SEM examinations were carried out on the representative samples taken from conspicuous zonings in the lake. According to the results of the analysis, it has been determined that the predominant mineral in the area is bloedite; however, thenardite (Na2SO4), very little halite (NaCI) and gypsum (CaSO4.2H2O) accompany this precipitation. The sodium sulfate crustification (bloedite + thenardite), which reaches an average thickness of 3 cm over an evaporation area of approximately 187.500 m2 in Lake İshaklı, has economical potential with its proven reserve of about 12.500 tons.