A new study published in Nature Geoscience by researchers from the Hebrew University of Jerusalem and collaborators reveals the first natural evidence of nickel-rich metallic alloys deep within Earth’s mantle. These were found as nanoinclusions and microinclusions inside diamonds from South Africa’s Voorspoed mine, formed 280–470 km below the surface.
The diamonds also contain coesite, potassium-rich aluminous phases, and solid nitrogen, confirming their deep origin. The coexistence of nickel–iron alloy and nickel-rich carbonates points to a redox-freezing reaction, where an oxidized melt infiltrated reduced mantle rock, triggering diamond formation.
