Mount Weld is among the richest rare earth deposits in the world.
The deposit is hosted within a carbonatite pipe of about 3 to 4 km diameter.
There is no surface expression of the Mount Weld carbonatite because it is covered by alluvium and lacustrine sediments.
An aeromagnetic survey delineated a circular anomaly, typical of a carbonatite intrusive pipe.
A gravimetric survey delineated a similar circular anomaly. Gravity data show the intrusion is associated with a positive 6 mGal. anomaly.