By inspecting rock samples from the Vergenoeg fluorite mine in South Africa, they found that the phialite crystals in the granite-like magma sediment can contain large amounts of heavy rare earth elements. The mineral, from reddish-brown to black, is extracted mainly for use as a gem and also for sandblasting. Faialite can be found worldwide in igneous and abyssal rocks.
Faialite crystals in granite-like magma sediment may contain large amounts of heavy rare earth elements
“Atomic probe tomography maps confirm the incorporation of HREEs into the phialite crystal network, facilitated by lithium acting as a main load balancer and high REE content in the highly fractionated felsic parental melt that is related to Bushveld LIP [large igneous province], ”Says the article. “The high HREE concentrations of fayalite together with its high modal abundance (> 95 vol%) indicate that the fayalite cumulates are the main host for the HREE mineralization of the Vergenoeg deposit.”
To reach this conclusion, the scientists used plasma mass spectrometry analysis inductively coupled to laser ablation and noted that the fayalite accumulated in the Bushveld LIP Paleoproterozoic deposit F-Fe-REE contains the highest levels of heavy REE ever recorded for mineral olivine, with HREE enrichment up to 6000 × chondritic values.
“As elements of heavy rare earth are becoming increasingly scarce on the world market, the discovery of phialite as a potential new source for locating new rare earth deposits is extremely important for the economy,” Reiner Klemd, one of the authors of study, said in a press release.
Currently, the most well-known and economically viable sources of rare earths are located in China, where more than 80% of them are refined. This resulted in an almost monopoly situation, with the Asian giant dominating international trade, especially in heavy rare earths.