Composition and origin of barite ores studied in Qerdaha region. The fieldwork was done on geological sections belong to Maastricht, from which many nodules like specimens were taken. Both mineralogical and chemical composition of the specimens were determined using XRD. Petrological study was done, as well.The mineralogical composition of most nodules consisted of barite-calcite of various percentages. The nodules at northern part of studied region consisted of barite or barite-calcite, turned into calcite or calcite-barite phases towards south.