A controversial new theory by a U of T geologist claims that some diamonds are created in the ocean and may even have their roots in living creatures. Dr. Daniel Schulze’s paper in the May 1 issue of Nature outlines the new technique that allowed him to determine that diamonds from the remote area of Guaniamo, Venezuela, were created on the ocean floor.
A typical diamond begins life when lava is expelled from the earth’s crust and hardens into volcanic rock. If this rock is then crammed under the earth’s continental plates, intense heat and pressure create vibrant red and green rocks termed eclogite. And, if carbon is present in the right conditions, eclogite may contain diamonds.
In principle, one could tell where the original material for the eclogite came from. Volcanic rock spewed into the ocean has a telltale oxygen composition. Unfortunately for scientists, the longer eclogite remains as mantle stuffing, the more it loses its original oxygen composition and takes on the oxygen content of its environment.
Diamonds, however, are impermeable, and can preserve inside themselves a record of the conditions that existed during their formation. By using an instrument called an ion microprobe, Schulze and his team were able to analyze the contents of oxygen-containing minerals within the diamonds. The minerals more closely resembled those found in ocean-altered volcanic rock rather than in mantle.
Moreover, the Guaniamo diamonds may have even once been living organisms. As all living matter contains carbon, and diamonds are simply regular crystals of carbon atoms, it is conceivable that what was once a fish is now a diamond. Schulze is convinced the diamonds he examined, and possibly thousands of other diamonds from around the world, have biogenic carbon signatures and were made by living material.
Hopefully the idea of compressed sea scum won’t detract from the immense worth of these shiny rocks, which reap billions every year on world markets.
