Rare-earth rich carbonatites: a review and latest results

Carbonatites contain some of the highest concentrations of REE in the Earth's crust. Levels of hundreds of ppm REE are characteristic but concentrations can exceed 10 wt.%. Such rare-earth rich carbonatites are common minor components of carbonatite complexes. They are often ferrocarbonatites and, even if only minor components of a carbonatite complex, can still host the majority of the REE. When, more rarely, the rare–earth rich carbonatites occur in larger quantities they are of economic importance. Rare earth minerals form in the ...