The discovery of diamonds and deep mantle minerals in chromitites of Hegenshan ophiolite, Inner Mongolia

Abstract: Diamond and other deep mantle minerals, previously found in the Mesozonic Tibet and the early Paleozoic Polar Ural, Russia, are now found in ophiolite mantle peridotite chromite. Hence the traditional opinion holding shallow origin of ophiolite and chromite should be reconsidered. In order to find out the distribution of diamond and other deep mantle minerals in different orogenic ophiolite chromites and to investigate the formation processes of the Hegenshan podiform chromitites, the authors carried out mineralogical study of chromitites in the Hegenshan ophiolite, Inner Mongolia. Approximately 2000 kg of mainly disseminated chromitite ore were collected from Hegenshan No. 3756 orebody. By mineral separation, preliminary studies identified more than 30 mineral species in addition to diamonds and moissanite. The other minerals include minerals of oxides, sulfides, silicates, and other compounds. This study demonstrates that the formation and tectonic setting of Hegenshan ophiolite and the chromitites deserve reevaluation.