JERUSALEM, Sept. 28 (Xinhua) — Israeli, U.S. and British researchers have discovered some microscopic metallic alloy features in diamonds formed 280-470 km beneath Earth’s surface, providing the first direct evidence of nickel-rich alloys at the depths where they were long predicted to exist, the Hebrew University of Jerusalem said in a statement on Sunday.
The discovery supports key models of the mantle’s chemical processes, helps explain how iron and nickel interact deep beneath the surface, and provides insight into the internal chemical forces that influence Earth’s formation.
For decades, mantle rock studies, lab experiments, and thermodynamic models have suggested that a nickel-rich metallic alloy will form around 250-300 km underground. However, no nickel-rich alloy has ever been seen in these depths.
In the study published in Nature Geoscience, the team discovered nickel-iron nanoinclusions and nickel-rich carbonate microinclusions in diamonds from South Africa’s Voorspoed mine, one of the largest diamond mines worldwide.
According to the researchers, the presence of both nickel-iron alloy and nickel-rich carbonate inside the diamonds suggests a dramatic underground event, during which molten material rich in carbon and oxygen moves into metal-bearing rocks, triggering a fast chemical change that creates diamonds and unusual minerals.
The diamonds also contain rare minerals that pinpoint their origin to far beneath the Earth’s surface, not in shallower layers.
The researchers said the study underscores the scientific value of diamonds as more than just gemstones, noting that diamonds act like tiny time capsules preserving reactions that shape Earth’s evolving interior. ■