Diamond exploration in the past used to be a matter of finding and following kimberlite pipes to their sources. Kimberlite is a potassic, magnesium-rich, volcanic, hypabyssal rock that brings diamonds from the mantle to the surface during eruptions. More recently, another geophysical method uses magnetics and electromagnetics. However, both of these methods are extremely expensive, time-consuming and can be inaccurate depending on the mineral composition of the subsurface as well as the surrounding environment.

Here is where microbiology can help. By collecting soil from potential diamond-rich subsurface kimberlite pipes, microbiologists can analyze the DNA profiles in those samples for specific indicator species of bacteria. Each species of bacteria can serve as a “biological fingerprint” as they possess genes with specific sequences. Using high-throughput DNA sequencing techniques, scientists can quickly and cost-effectively find out which bacteria are present in a given soil sample and compare it with the DNA sequences of various diamond-indicator bacteria species in their database.

This method is advantageous as it does not depend on the size of the kimberlite pipe or the geology of the area, and it can easily delineate kimberlite pipes from other rock types. In fact, research teams from De Beers and the University of the Free State in South Africa have already had successful field trials of this method in various parts of South Africa.

Furthermore, the technology to analyze soil and obtain DNA sequences with high throughput is constantly improving and becoming cheaper, making this method very attractive to mining companies worldwide.