Scientists in South Africa have discovered two rare diamond samples in a South African mine, carrying unique information about the Earth’s internal chemistry and how diamonds form at great depths. According to “Russia Today,” these stones formed hundreds of kilometers deep within the Earth’s mantle and contain unusual impurities of oxygen-rich carbonate minerals (oxidized state) and oxygen-poor nickel alloys (reduced state).

The coexistence of these two types is extremely rare, to the point that scientists described it as “almost impossible,” because the two chemical environments cannot coexist for long. Dr. Yaakov Weiss, a professor of Earth sciences and the lead researcher of the study, explained that these impurities represent “an aspect of the oxidation process” within the Earth’s mantle and constitute the first direct evidence of deep chemical reactions previously unobserved.