There's some in Brazil so I assume it can be found in appropriate conditions globally. I'm pretty sure AU will have some, because AU always seen have some. The issue still is going to be process/seperation, where main point is clay leeched HREE at scale didn't exist before PRC commercialization, so it's not just let's dust off old mineral textbooks, need to rediscover the entire tacit knownledge process for high purity extraction.

E: brushed up a little bit from a few month ago and AU just found some clay, because of course they did.