Barite deposits located in Marsis locality of about 25km northeast of Zakho City were hosted in Jurassic dolomitic rocks. The barite is extending for about 6km and limited within about 38m thickness of dolomitic rocks. The thickness of the barite veins varies between few centimeters to 2.5m which increases downward. The major mode of occurrence of barite is as vein and cavity-filling. The barite and other minerals of vein and cavity-filling deposits are typical of suite precipitated from low-temperature hydrothermal solutions associated with igneous activity. Carbonate-hosted barite deposits contain 0.237% BaO, 103ppm Zn, and 83 ppm Pb. These rocks are deficit in Fe and F. Most of carbonate rocks are dolomitized, which provide appropriate physical and chemical conditions that permitted the passage of mineral-bearing fluids. These deposits are formed in carbonate platform setting and commonly developed in foreland thrust belt.