New Study Links Brazil’s Black Diamonds to Ancient Impacts and Deep Mantle Formation
A new study published in Gondwana Research proposes that carbonado, the porous black diamonds found in Brazil and Central Africa, formed deep within Earth’s mantle rather than at the surface. Researchers Attila Demény and colleagues analyzed samples from Brazil’s Tombador Formation, finding that their glassy surfaces likely resulted from later fluid dissolution rather than direct impact melting. The team suggests that ancient cosmic impacts may have driven rapid subduction, carrying carbon-rich organic material from the surface into the mantle, where extreme pressure transformed it into diamond. This hypothesis explains the stones’ unique porous structure and mixed mineral content, though it remains a theoretical model lacking definitive proof of a specific impact event.