Evaporites deposits have a wide distribution in nature, they could be formed under a variety of environments (Marine, continental, lagoon, lake, fresh water and springs environments). Together with the carbonate rocks evaporites from a large part of the sedimentary rock column. The Lower Fars Formation has a wide geographic distribution in Iran-Iraq-Syria, it is typically consists of gypsum or anhydrite, salt, limestone, red and green marl. The present study attempts to use the geochemical properties of trace and major elements of gypsum and anhydrite to determine the depositional environment. The petrographic study deals with the diagenetic changes (recrystallization and replacement), and their relation to the geochemical behavior of the trace and major elements. Three sections of the Lower Fars Formation (Middle Miocene) were selected to study the geochemistry and petrography of the gypsum and anhydrite, Jabel (Mountain)Makhul section (Near Al-Fat''ha area), Jabel Ibrahim (40 Km west Mosul city), and a subsurface section in Kirkuk Oil Field (from well No. K 214).