The ionic adsorption clays are a process enabling geology. You must have:
- rare earth containing rocks on the high ground,
- Ionic adsorption clays formed on the low ground,
- Thousands of centuries of rain,
and, to extract:
- Ammonium salts,
- Plastic tarps, pipes, and tanks.
- Oxalic acid.
- Low cost labor.
- A forgiving or autocratic government
Whilst tongue in cheek, that gives a fair idea of what’s needed. Source rocks with REs, a depositional environment, time and water …. and a method of extraction (ionic forms of heavy rare earth salts attached to the clays are rapidly dissolved into ammoniacal solution and since this solution has thousands of times the solubilizing power for heavy rare earth salts that pure water has, these heavy rare salts may be thereby “solubilized” and concentrated by precipitation with oxalic acid ).
I’m not a pedogenesis guy, but the AR3 presentation gives a fair indication of the surficial deposits, of lenticular clay beds interspersed with sandy layers, mineralised at the base where they sit on top of the local bedrock, Gambier limestone, and above the water table.
Analysis of the early resource show the layers to be at a depth between 2 and 9m. Sampling has been done with some 470 aircore, auger and pushtube drill holes across the whole region, by Mines Dept and now AR3.
So, what are we left with? This part of the world is relatively flat, with a stable geologic history. With 725ppm as a cutoff, the company has identified laterally extensive REE mineralisation within a (on average) 2 to 3 metre thick clay horizon across two prospect areas, Red Tail (10km x 3km) and Yellow Tail (3km x 1.9km).
The resource contains a relatively high proportion of heavy rare earths, particularly Dysprosium and Terbium, along with Neodymium and Praseodymium, all of which are used in rare earth permanent magnets.
The metallurgical testwork indicates TREO (excluding Ce) recoveries of between 50% and 70%, with with low radioactivity.
Any mining is slated to be Shallow free digging material with low strip ratio • Progressive rehabilitation. And that brings us to environmental issues.
AND Coonawarra is nearby. The best wine is from the terra rossa soils on top of the limestone: well-drained, reddish, clayey to silty clayey soil with neutral pH conditions…. The reddish color of terra rossa is the result of the preferential formation of hematite over goethite
Wrattonbully => fair game, Padthaway => ditto, but stay away from Coonawarra