Whatsupdoc-- In 1955, around the time that Steens was being prepared for first production of Thorium, the following "Geological Survey Professional Paper No.300 was published. It's title was "Contributions to the Geology of Uranium and Thorium by the United States Geological Survey and Atomic Energy Commission for the United Nations International Conference on Peacful Uses of Atomic Energy, Geneva Switzerland, 1955"
Wow...what a mouthful...
On page 624 of that huge tome, the authors (I can't cut and paste, but I will paraphrase) detailed that in recent(pre-1955) searches for Uranium and Thorium, Aircraft had been used to fly over suspected deposits at an altitude of 500 feet with Scintillator detectors on board which were used to pinpoint locations of increased radioactive radiation, indicating the presence of the minerals such as monazite which bore significant grades of the desired elements.
So...All the way back in '55, yes, there was unclassified publications explaining in quite a bit of detail how that radioactivity could be used to find the good stuff. Of course, walking around on the ground with more modern equipment will easily indicate, probably with much more precision, the location and amount of the radioactive material, which in the case of Monazite, means Thorium, and where Thorium is, at least the the area of Steens, there is REE.
I believe it is safe to assume that the geologists working at Steens for the last 3 years have probably been doing just that, and that the accuracy of the diamond drilling showing such high grades was probably based on just that sort of work. I would suggest further that they might have strayed a few kilometers or so off the "reservation" and poked a sensor or two into the surface outcrops of what is now the approved 574 square Km exploratory area. Anybody think that might have been the reason for the application to officially "explore" those areas?