Idri salt deposits, Fezzan Province, Libya

Abstract

The Idri salt deposit, located 135 kilometers west of Brack in the Shatti Valley area of the Fezzan province, United Kingdom of Libya, covers an area of about 35 square Kilometers. It is connected to the newly constructed black-top Fezzan road by about 250 kilometers of secondary road. The deposit is a salt flat that lies in a closed depression. It consists of a hard crust commonly 20 to 40 cm thick overlying 40 cm of salts and wet sand above the brine. The origin of the deposit is attributed to the percolating waters that concentrate into a brine and then by capillary action and evaporation form a crust on the surface. Experiments with fractional crystallization by solar evaporation in the field indicated that fairly pure table salt may be obtained in the first stage of evaporation, and a product containing about 6 percent K 2 0 equivalent may be recovered in the second stage. Laboratory experiments indicate that by the dissolving of the natural crust and recrystallization by artificial heat a salt mixture containing about 7 to 10 percent potassium may be recovered. No future geologic work is recommended for the area but it is suggested that the deposit may be worked on a small scale to recover a pure table salt and, if the conditions warrant, the residual brine may be further treated to recover potash as a by-product.