You are right, unlikely it is being stolen. The Google images show that the pile has systematically been undergoing removal since 2022. Whether it is being crushed for road gravel or possibly being processed for precious metals locally....not sure.
There appears to be some kind of processing going on in the area just to the south, some trenches, some other disturbance, new roads, clearing. Possibly someone thinks they can make money crushing and processing that low grade material as long as they don't have to move it very far.