New research can potentially change the way miners look for diamonds: In a collaborative effort between University of Alberta geologists and diamond miner De Beers, lherzolite – a coarse grained rock – was found to be an exciting new source for diamond formation. The research was published in the latest edition of the Mineralogy and Petrology journal.
The Potential of Lherzolite
Lherzolite is a common rock type in Earth’s mantle which, so far, has been only peripherally associated with diamond formation. Diamonds in ancient continental regions, such as the Canadian Shield, were previously thought to have grown mainly in different types of mantle rocks. Now, say the researchers, “this assumption […] is being turned on its head”.
The research used samples from the De Beers Group Victor Mine in northern Ontario, an area of the Canadian Shield “characterized by a large-scale heating event that occurred approximately one billion years ago, an unusual setting for a diamond mine”. According to Thomas Stachel, professor in the Department of Earth and Atmospheric Sciences and Canada Research Chair in diamonds, “the outcome of the project fundamentally changes our understanding of where diamonds come from. The discovery that economic diamond deposits can come from lherzolitic diamond substrates has the potential to cause diamond companies to retool their approach to exploration”.
The University of Alberta invested almost $30 million into analytical facilities that allow probing the age and origins of diamonds at the micro-analytical level. “We’ve dated and analyzed the makeup of diamonds, their miniscule inclusions, and the mantle itself”, Stachel explained, “The level of detail collected in this study couldn’t be done anywhere else in the world”.
According to Stachel, the research suggests that the results for the Victor Mine “may well apply to other regions around the world that experienced geologically ‘young’ overprint, in particular in Western Canada”. In the long run, he added, “this could make a big difference in diamond exploration”.
