The thinking is probably along the lines of, "This area has been...

The thinking is probably along the lines of, "This area has been proven to be high in rare earths, so let's grab an unclaimed area nearby and hope that the mineralisation continues out further." As mac3 said, the carbonatite fades out beyond Peak's tenement; a large part of why Peak has such high grades is because the mineralisation has weathered, concentrating the rare earths in ways that make them much more amenable to relatively easy processing. I think Peak has pretty much the entirety of the high value prospect; the surrounding area is unlikely to hold significant value unless the rare earth pricing appreciates significantly more than it already has (and even then, I'd class it as dubious.)

Speculative land grab, in other words, and unlikely to come to much.