Overview

• Researchers identified nickel–iron metallic nanoinclusions alongside nickel‑rich carbonate microinclusions inside Voorspoed diamonds formed 280–470 km below Earth’s surface.
• The discovery provides the first natural confirmation that nickel‑rich alloys stabilize at depths long predicted by mantle redox models.
• Coexisting alloy and carbonate record a transient metasomatic redox‑freezing event in which an oxidized melt infiltrated reduced, metal‑bearing peridotite.
• Additional inclusions such as coesite, potassium‑rich aluminous phases, and solid molecular nitrogen constrain formation to the deep upper mantle and shallow transition zone.
• The peer‑reviewed study, led by Hebrew University with collaborators from the University of Nevada and the University of Cambridge, was published in Nature Geoscience on September 22 and outlines implications for volatile‑rich magmas including kimberlites.