How about Mt Weld?

Crown Deposit niobium, tantalum resources at January 2010 (Lynas Corp.)
indicated + inferred resource - 37.7 Mt @ 1.07% Nb2O5, 1.16% TLnO, 0.09% Y2O3, 0.3% ZrO, 0.024% Ta2O5, 7.99% P2O5;

Global resources:
The regolith over the carbonatite was estimated (1989) to contain an indicated resource of (Duncan and Willett, 1990):
250 Mt @ 18% P2O5,
270 Mt @ 0.9% Nb2O5,
145 Mt @ 0.034% Ta2O5,
15.2 Mt @ 11.2% lanthanide + yttrium oxides

Porter Geoscience data base Mt Weld. and other.

I did a fair search to see if I could get any good info on the Nb at Mt Weld but only got a few hints and then from pre 1990 open file reports.
The interest in REEs has varied over the years. Europium was a biggy last century with much coming from Mountain Pass. Now it is battery elements which were analysed but disappeared into La and Y in the reports from the 1980s. Similarly the others listed in the global resources above receive scant coverage in what are statutory government reporting (both then and now).
Lynas announcements seldom contain much obvious exploration data between 2007-2021 while developing and getting to production. Probably more a lack of research by me, but the focus is where it should be - getting cash flow.

I suspect the global resources above came from wide spaced drill in the late 1980s. Detail on the REEs of the Duncan deposit and 100-500m grid drilling to a maximum depth of 200m (probably less than 100m on average) as shown in this early plan.


Zooming in on the plan view and adding a rough outline of Luni. Mt Weld is 'circular' and Luni a beached whale shape about half the NS dimension. Both large beasts.




Deposit size defined by cut off grades, continuity. Tonnage depends on size and specific gravity (SG).
SG in weathered units is difficult to calculate accurately but is mainly less than the fresh rock.
Carbonatite average ~2.8 but varies.
Most weathered units come in around 2 with those at Mt Weld possibly being assigned a lesser value
Only reference found was this from 1989 (A29388).


Suspect the value used now is higher than 1.4.

Luni's bulk grade will likely be in the 1-1.5% range of Niobium (Nb205) after the lower grade halos are included. There will be some very high grade zones though lower tonnage. Hopefully more rather than less. Will be significant.

Mt Weld holds a large resource on Nb. The REEs though are a true treasure chest that far outshine other possible world class commodity options there. Perhaps other factors why other commodity production is on the back burner.