Same general location and cause for occurance and deposition. Containment in intrusive veins, like uranium makes retrievable mining in metamorphic formations difficult and espensive.

While the Wet Mountain formations are estimated to contain a large amount of thorium, that estimation is the sum total of the whole mountain range. It is ridiculous and impractical to mine an entire mountain range. Only idiots like the fool felon would argue, and I'd wager he has no idea what thorium is, or that is even exists.

Climax for example has been mining molybdenum from one mountain for well over a half century, and that one mountain is less than half mined! Molybdenum is far more abundant than thorium.