Ann: Coincident Gravity/Magnetic Anomaly at Carbonatite Target, page-11

Occurrence. Overall, 527 carbonatite localities are known on Earth, and they are found on all continents and also on oceanic islands. Most of the carbonatites are shallow intrusive bodies of calcite-rich igneous rocks in form of volcanic necks, dykes, and cone-sheets.

How rare is carbonatite?Although there are more than 500 known carbonatites in the world, currently only four are being mined for REEs: the Bayan Obo, Maoniuping, and Dalucao deposits in China, and the Mountain Pass deposit in California, United States.

Good luck, suddenly everyone has a carbonatite with Nb in it