As a general rule REE 'discoveries' have problems - if clay,...

As a general rule REE 'discoveries' have problems - if clay, they are absorbed (internally) rather than adsorbed (surface) - if hardrock, costs get the better of profit.
Not always of course. But then we have China with their large clay deposits which they treat in situ with shocking consequences to the environment.
Then you have to crack open the monazite and separate all the different rare earth metals.
If you have niobium and tantalum, things are different because they come in different source minerals and would leave the mine site in different bags.

No doubt every deposit is different, but I would much rather be in the Nb/Ta neck of the woods, than a pure REE play.
(I need to make one quallification re AHK's deposit - because I post there with a very positive view - AHK has monazite based rare earths in a pure sand environmentment. By simple on site gravity separation the heavies can be concentrated from ~ 0.5% REEs to ~ 52% concentrate to be bagged and shipped.)

For SUM, I am keeping an open mind re REEs - and Li to, but am full on for the prospect of a major Nb and Ta discovery.

Clearly just my personal views - not advice, DYOR, and be aware of risk associated with such an early discovery prospect.

Cheers and GL all.