From...

From @scarpa: 

https://hotcopper.com.au/threads/ree-information-thread.4276965/page-8?post_id=34616622

"Additionally, it should be noted that REE resources, as opposed to REE reserves, have not have demonstrated economic viability. Reserves could be economically extracted or produced at the time of determination, while resources are merely an indication of potential economic feasibility, and the global REE resources, therefore, are substantially higher than figures published by the USGS [22] (126 Mt REO). About 27% of these deposits have REO ore grades <0.2%; 55% of projects have REO ore grades <1%, and only 5% of deposits have REO concentrations >10%. While almost all of the current REE deposits in production have REO ore grades >1%, such as 8.8% in the Mount Weld central lanthanide deposit (CLD), 5% in Bayan Obo, and 1.12% in Levozero, about 42% of these deposits are below the medium size, and 76% contain <1 Mt REO. While 5% contain >10 Mt REO, these giant deposits need to be further exploited and developed in the future."