New Research Uncovers Deep Earth Origins of Africa's Giant Diamonds

New research is illuminating the extraordinary geological processes responsible for producing some of Earth's most remarkable diamonds. These precious stones, often of immense size, are known as CLIPPIRs, an acronym describing their Cullinan-like, Large, Inclusion-Poor, Pure, Irregular, and Resorbed characteristics. According to AllAfrica Top, these CLIPPIR diamonds represent a tiny fraction—less than one percent—of all diamonds globally. Despite their rarity, they encompass several of the largest and most famous diamonds ever unearthed. Notable examples include the colossal 3,106-carat Cullinan diamond, discovered at the Premier mine in South Africa, and the 1,111-carat Lesedi La Rona, which emerged from Botswana's Karowe mine in 2015 and later sold for an impressive US$53 million. The 2,492-carat Motswedi diamond, also found in Botswana, further exemplifies this rare category. A collaborative international study, published in the journal Nature, delves into the origins of these exceptional gems. Researchers analyzed the mineral inclusions present within CLIPPIR diamonds, which provide crucial clues about the mantle rocks from which they crystallized. The findings indicate that these diamonds formed at extreme depths, specifically within the Earth's lower mantle, at pressures ranging from 23 to 25 gigapascals. This corresponds to depths between 400 and 700 kilometers below the surface, a region far deeper than where most conventional diamonds are created. The research suggests that CLIPPIR diamonds originate from a distinct reservoir within the deep mantle, characterized by its low oxygen content. This unique environment is rich in metallic iron and has an unusual chemical composition. These deep conditions contribute to the diamonds' signature characteristics, such as their low nitrogen concentration and large, irregular shapes, which often show signs of being partially resorbed, or dissolved, during their journey upwards. This novel understanding challenges previous assumptions about diamond formation and highlights the complex interplay of pressure, temperature, and chemistry deep within our planet. The discovery of such deep-seated origins provides a fascinating glimpse into the dynamic processes shaping Earth's interior and how these processes can yield such magnificent natural treasures. The insights gained from studying these inclusions not only enhance our knowledge of diamond genesis but also offer a unique window into the composition and evolution of Earth's lower mantle. Continued research promises to unlock more secrets about these ancient and valuable geological wonders.