Ann: West Arunta Project - Luni Assay Results, page-742

Is there no-one with any understanding of geology over at SUM. They have a pegmatite they are looking for Niobium in, not a weathered carbonatite.

The pegmatite is a fractionated system where separation of minerals happened as the ancient melt solidified, causing various veins of the rarer elements and minerals. SUM have some thin seams as identified by the company, that contain some coltan among other crystals like tourmaline.
Some of the crystals in the veins are coltan form the photos, however much of the scattered dark looking crystals will be tourmaline.

Once SUM put the drill bit into the ground it will be game over as the coltan crystals that were collected for rock chip samples are few and far between throughout the deposit.

Artisanal miners have been able to go along and mine out the veins where shallow enough to eek out a living in a poor country. Bulk mining because of the density of the pegmatite will not work on extremely low grades of Niobium and Tantalum that they will find in whole rock samples.
The weathered portion of the pegmatite could be mined as it leaves the high grade crystals of coltan behind, however I would think that is what the artisanal miners have been grabbing for decades, leaving the hard to get minerals in the very hard pegmatite behind.