Nobody should have thought I was writing off undrilled carbs, though one poster muddied the waters by continually inferring I was. As you well referenced, carbonatite hosted deposits are nearly always formed in smaller areas of larger carb-complexes with the right enriched carb intrusion/source, and/or fluid structure/breccia to pipe/trap RE mineralisation +/- valuable elements. Weathering deflation upgrades primary RE mineralisation >4x, which is why supergene enriched laterites represent good targets.
Higher, better continuity grades makes supergene blankets larger targets than potentially 'patchy' structurally controlled primary RE mineralisation. DRE designed 160m centres to test the C1-C5 carbs to avoid the chance of missing a material deposit I presume. Drilling proved deep weathering and RE enrichment in oxides, which probably means the original 160m centres are probably more than enough than if C1-C5 had a shallow weathering layer. Longonjo (Pensana), Ngualla (PEK) Cummins (REE) are typical examples of weathering enriched RE deposits are with similar footprints to C3 enriched footprint.
![https://hotcopper.com.au/data/attachments/5188/5188497-87b794913c80e4dbcd6a9a8dabcf6a6b.jpg](https://hotcopper.com.au/data/attachments/5188/5188497-87b794913c80e4dbcd6a9a8dabcf6a6b.jpg)
![https://hotcopper.com.au/data/attachments/5188/5188502-1ff298c1ffd62d009967715a21c65611.jpg](https://hotcopper.com.au/data/attachments/5188/5188502-1ff298c1ffd62d009967715a21c65611.jpg)
![https://hotcopper.com.au/data/attachments/5188/5188503-7139b45c0d5f545f2353744c1d9cd2ea.jpg](https://hotcopper.com.au/data/attachments/5188/5188503-7139b45c0d5f545f2353744c1d9cd2ea.jpg)
These images demonstrate the footprint of large deposits in laterites, even small deposits will have a decent footprint at elevated grades. They also demonstrate the critical grade enrichment compared to RE grades/distribution in fresh rock. I wouldn't bother drilling more deeper holes than they need to understand the nature and distribution of primary RE mineralisation (which I'm sure they now have, other than it helps meet the 2023 MRE performance rights target). C3 will always be 'open at depth' because carbs are deep seated intrusions, but if MRE infill drilling of the supergene layer doesn't come up with better than 1% TREO intersections, the primary source is going to bulk out 2-4x lower grade. REE tried drilling under very thick >2% TREO supergene ore chasing the primary HG breccia structures, but it broke up and bulked out much lower grade unsurprisingly.
I'm not going to address in detail the economics of 1% TREO, 22% NdPr ratio oxide carbonate deposits here (note ironstone hydrothermal dykes are very different) but these three examples have Mine Reserve or equivalent grades much higher than their MREs. The simplest way for non-technical investors to judge what grades mean for economics in any commodity is look at the relevant competition. 2% TREO for low-20's NdPr ratio oxide ore is the minimum to try and get over the line, and frankly usually not enough considering low recoveries and low TREO% concentrates derived from oxide monazite ores.
Oxides just don;t float well, carbonate hosted deposits are mineralogically much more complex than the sweet simple ironstones like Yin. C3 @ 1% TREO and 22% NdPr ratio = 0.22% NdPr, which isn't a lot to make bank when concentrate grades to feed an expensive hydromet plant are around 15% TREO Longonjo and Cummins. Bastanite floats better than monazite, thus Ngualla can produce a concentrate at 45% TREO from oxide ore. The reagents to float an oxide C3 carb ore is almost certainly very different to what is required to float Yin ironstone, so you can;t just bang C3 ore into a Yangi style bene plant. Any carb hosted deposit DRE discovers really wants to be close to stand alone imo if it's going to add value to the share price...
![https://hotcopper.com.au/data/attachments/5188/5188533-8daae7203d887c895e23bb2cee8bf5f7.jpg](https://hotcopper.com.au/data/attachments/5188/5188533-8daae7203d887c895e23bb2cee8bf5f7.jpg)
![https://hotcopper.com.au/data/attachments/5188/5188534-afa9d541cd703e9eb17fb8223c5f8453.jpg](https://hotcopper.com.au/data/attachments/5188/5188534-afa9d541cd703e9eb17fb8223c5f8453.jpg)
![https://hotcopper.com.au/data/attachments/5188/5188539-211c9c04437e687b26ee96ec85755055.jpg](https://hotcopper.com.au/data/attachments/5188/5188539-211c9c04437e687b26ee96ec85755055.jpg)