The short version is this:
Cryolite was the only thing they were looking for and many people died bringing it to the world and across ice filled oceans. Many ships sunk exporting it out.
Cryolite was easy to spot and separate from other rock and ore because it was "white as snow"
Cryolite was only found in this place
Due to the location and Cryolite being "White Gold" the old timers had no reason to mine anything else and risk shipping it out when the "white gold" boats sunk enough.
Chasing white gold the old timers sunk kilometres of test holes chasing more Cryolite as the ore started thinning out.
The old timers did not care for USD$300,000,000 of Zinc in the hole, let alone REEs when the IPhone was 130 to 40 years away
Alas there is 19km of drilling ready to review, $300,000,000 of zinc in the pit, heaps of Quartz and [cross fingers] ore filled with REE.
and it's 2c a share and not including the uranium and manganese holdings in Australia
(20min delay)