Hobart M. King, PhD, rpg rare Earth Element Production

Rare earth oxides: These rare earth oxides are used as tracers to determine which parts of a watershed are eroding [5]. Clockwise from top center: praseodymium, cerium, lanthanum, neodymium, samarium, and gadolinium. Image by Peggy Greb, USDA image gallery.
World Rare Earth Mineral Resources
"Rare earths are relatively abundant in the Earth's crust, but discovered minable concentrations are less common than for most other ores. U.S. and world resources are contained primarily in bastnäsite and monazite. Bastnäsite deposits in China and the United States constitute the largest percentage of the world's rare-earth economic resources, while monazite deposits in Australia, Brazil, China, India, Malaysia, South Africa, Sri Lanka, Thailand, and the United States constitute the second largest segment.
Apatite, cheralite, eudialyte, loparite, phosphorites, rare-earth-bearing (ion adsorption) clays, secondary monazite, spent uranium solutions, and xenotime make up most of the remaining resources. Undiscovered resources are thought to be very large relative to expected demand." Quoted from the United States Geological Survey's Mineral Commodity Summary [9].

Rare Earth Element References

[1] Rare Earth Elements - Critical Resources for High Technology: United States Geological Survey, Fact Sheet 087-02. [2] Rare Earths: Daniel J. Cordier, United States Geological Survey, Mineral Commodity Summaries, January 2022. [3] Smartphone Ownership Is Growing Rapidly Around the World, but Not Always Equally: Laura Silver, Pew Research Center, article on the Pew Research Center website, February 2019. [4] Scandium: Daniel J. Cordier, United States Geological Survey, Mineral Commodity Summaries, January 2022. [5] A Rare-Earth Approach to Tracing Soil Erosion: United States Department of Agriculture, Agricultural Research Service. [6] China's Ace in the Hole: Rare Earth Elements: Cindy A. Hurst, National Defense University Press. [7] The Geology of Rare Earth Elements: Republication of "The Principal Rare Earth Elements Deposits of the United States - A Summary of Domestic Deposits and a Global Perspective." [8] Rare Earth Elements and National Security: Eugene Gholz, Council on Foreign Relations Energy Report, 2014. [9] Rare Earths: James B. Hedrick, United States Geological Survey, Mineral Commodity Summaries, January 2008.