A team of petrologists and crystallographers from Canada and Japan have discovered maruyamaite, the first tourmaline species that is both diamond-bearing and potassium dominant.
Maruyamaite was found in northern Kazakhstan and is named in honor of Shigenori Maruyama, professor in the Earth-Life Science Institute at the Tokyo Institute of Technology. Maruyama led the project which unraveled the manner in which the ultra-high pressure rocks were formed.
The petrologist Darrell Henry – from the Louisiana State University and one of the team members, said that “Normally, tourmaline contains very little potassium, but the unusual high-pressure environment and potassium-rich melts that these rocks have experienced contribute to the formation of this unusual species,”. He added that the discovery of diamond in tourmaline shows that the species can develop at extreme pressure conditions in the crust of the earth where two continents have collided to push near-surface rocks to depths of more than 80 miles.
No, no valuable diamond deposits expected; “only” more knowledge about Earth processes and the curiosity that two gem minerals (tourmaline and diamond) occur together in exotic geologic terrains. You may read more (or differently) at LSU website. An article detailing this finding will appear in the upcoming issue of American Mineralogist.