So far, no documented geological evidence of diamond potential has been observed in the Iranian crust. However, geological formations and assemblages in Iran exist that allow for the possibility of diamonds. This study examines geological formations and assemblages with diamond potential for future geological explorations.
Among the geological formations and assemblages with potential diamond content, kimberlites and lamproites containing diamonds have not been reported in Iran. Nevertheless, geological assemblages in Iran with potential diamond potential include eclogites and ophiolites suites with diamond-bearing potential, ultra-high-pressure (UHP) metamorphic rocks, and meteorite impact sites.
Diamond-potential eclogites are characterized by high concentrations of magnesium-rich garnets (pyrope or magnetite-rich almandine) and amphibole, with the presence of coesite, orthopyroxene, clinopyroxene, Phlogopite, and sometimes spinel. Important locations for eclogite formation in Iran, such as the Shanderman eclogite (northwestern Iran) and the Sistan region eclogite (eastern Iran), with their mineralogical, petrological, and geochemical characteristics, can be further explored.
The diamond-bearing peridotites of Iran, with the presence of lower-crust and upper-mantle minerals and the unique chemical composition of the rocks in these areas, such as high concentrations of platinum group elements (PGEs), are valuable sets for exploring diamond-bearing peridotites. Among them, garnet-bearing (with chromium-rich spinels) deep-mantle peridotites containing high-magnesium olivine suites, orthopyroxenes along with clinopyroxenes containing high Mg (especially with the presence of metasomatic minerals such as Phlogopite, apatite, and amphibole), can be excellent evidence of diamond formation potential. The peridotite suites of Iran with specific geochemical characteristics, containing lower Al and Ca harzburgites but high Mg forsterite olivines, along with chromium-rich spinels and lower REE and Os concentrations than primary mantle, are also valuable sets to mention.