Microbes in surface soil may indicate presence of diamonds down below
Locating diamond deposits in the earth isn't always an exact science, so the greater the number of methods of doing so, the better. A new study now suggests that soil microbes may point the way to such buried treasures.
Currently, mining companies search for diamond deposits via techniques such as ground-penetrating radar scans or analysis of minerals in rocks on the soil's surface. That said, research has already shown that when ore interacts with overlying soil, it affects the type and numbers of microbes living in that soil.
With that fact in mind, scientists from Canada's University of British Columbia set about adding samples of a rock known as kimberlite to populations of various types of soil microbes. Kimberlite ore is the world's most common host matrix for diamonds.
After seeing which microbe species thrived and which ones perished, the researchers were left with a "biological soil fingerprint" for kimberlite. The team then analyzed soil samples obtained from an exploration site in Canada's Northwest Territories, where the presence of kimberlite had already been confirmed via drilling.
Based on microbial DNA in the soil, it was found that 59 of the fingerprint's 65 indicator species were present in the samples. Some previously unidentified species were also present in large numbers, so they were added to create a new-and-improved fingerprint. That fingerprint was then compared to microbial fingerprints obtained from a second site, where kimberlite was suspected to be present.
By making such comparisons, the scientists were successfully able to locate a kimberlite deposit located approximately 150 meters (492 ft) below the surface. The technique actually proved to be more reliable than a commonly used existing method known as geochemical analysis, in which chemical elements in the soil are tested.
Importantly, it is believed that once the technology is developed further, it could be utilized to search for other types of ore. It has already proven successful at locating porphyry copper, which is widely used in batteries.
"This is exciting because it's part of a growing recognition of the potential for using microbes at every stage of mining, from finding the minerals, to processing them, to returning sites to their natural states," said team member Dr. Sean Crowe. "Currently, microbial DNA sequencing requires specific expertise and is comparable in cost to other mineral exploration techniques, but this could change with industry adoption."
A paper on the research was recently published in the journal Nature Communications Earth and Environment.