Hidden Within African Diamonds, a Billion-Plus Years of Deep-Earth History | Lamont-Doherty Earth Observatory
(Yaakov Weiss) Most diamonds are thought to form some 150 to 200 kilometers under the surface, in relatively cool masses of rock beneath the continents. The process may go back as far as 3.5 billion years, and probably continues today. Occasionally, they are carried upward by powerful, deep-seated volcanic eruptions called kimberlites. (Don’t expect to see one erupt today; the youngest known kimberlite deposits are tens of millions of years old.) Much of what we know about diamonds comes from lab experiments, and studies of other minerals and rocks that come up with the diamonds, or are som...
Source: columbia.edu