It's just that no-one wants to mine them at great expense for little profit?
(edit: are not, not are)
The Wikipedia page on "rare" earths is very interesting:
https://en.wikipedia.org/wiki/Rare-earth_element
(sorry, I accept the downvotes in advance)
It's just that no-one wants to mine them at great expense for little profit?
(edit: are not, not are)