Mineralogical and Geochemical Characteristics of Dur Al-Najaf Gemstones from Al-Najaf Province, Central Iraq

Abstract

Dur Al-Najaf is considered one of the most distinguished semi-precious stones in Iraq, especially in the province of Najaf. A field survey was conducted in the areas within the Bahr Al-Najaf region and among the recent sediments and the Dibdibba Formation. The study aims to analyze the mineral and chemical makeup of this semi-precious stone, categorize its type, provide an overview of its typical attributes, and ascertain the origins and geographical distribution of these semi-precious stones. The samples underwent examination from a sedimentological, mineralogical, and geochemical perspective. Four distinct samples of stones, each representing a different color variant, underwent examination to explore their petrology through polarized light microscopy and mineralogy via XRD analysis. Additionally, three more stones were subject to SEM analysis. The results revealed three types of these stones which are pure type, oily type (gray), and Al-Husseini type (reddish brown). Results of XRD, XRF, and EDX analysis showed that these stones are various forms of pure sedimentary quartz mineral. Some of these stones contain impurities that give them varying colors, such as gray, which may have resulted from a high concentration of CaO, or red to reddish color, resulting from high FeO concentrations. These stones represent pieces of quartz minerals included in the components of the Dibdibba Formation, which resulted from the erosion and crushing of igneous rocks from the Arabian Shield that spread to wide extents in the Najaf Plateau.