Hi Paul, thanks for this post this is genuinely good information. It sits well with my somewhat basic understanding. I'll post my reasoning and opinions below but I am happy to be corrected by those more knowledgeable.
#2 the exchangeable phase is the ionic phase, as I've said before its the only way a clay structure can "capture" REE's. #1 and #3 phases I have called "contaminants" in a previous post. Probably a bad choice of words but I was attempting to point out its these phases that determine acid consumption because the REE's are still encased in a hard mineral structure. Its also worth pointing out the clay itself can weather into a harder mineral, shale is a good example, which if it occurs significantly, will reduce #2 and increase #3 and #1.
As I've said before, The Ce anomaly indicates a given system has been exposed to certain broad types of weathering/conditions that create the anomaly by keeping the Ce in its +3 state, and thus soluble and mobile, or oxidising to its +4 state, creating the insoluble and not mobile oxide. It is used in many geochemical settings, not just REE mining. Remember, you also need a physical migration of the Ce or other REE's, or both to actually create the anomaly, redox will not do it on its own. Many conditions can create this, I've mentioned high organic overburdens (forests, jungles etc..) can create this.
Now at this stage I don't accept that the two hole data you provided is fully representative of the whole 40sq/km but lets just say its is for arguments sake and there is no anomaly present. So what does that say? What's the mechanism that says ," so therefore the #2 phase has disappeared or was never there to start with?" This is where I get stuck.
The high levels of REE's assayed over such a broad area in the clays suggest to me at least it was there to start with. I'm pretty sure the average geo can tell the difference between clay and saprolites as well so I doubt that samples have been mixed up. So to my limited thinking to fit your hypothesis there must have been a process that has turned #2, back into #1 and #3, that hasn't affected the Ce oxidation state, (the most weathering prone of the REE's), but has affected all REE's and reverted their bonding back to hard mineralisation. And yet, for the "vast Majority" of IAC deposits we do see the anomaly. Are you suggesting that the obviously very special weathering processes they have experienced have helped create this coveted "ionic-ness"?? (You see for me how that doesn't fit, its the #2 phase that creates the "ionic-ness" to start with right?). To boot its done it in a way that doesn't seem to yet manifest any physical clues in the samples and drilling from the limited amount that I can see.
Anyway, for me the statement "The vast majority ..... present the negative Ce anomaly" simply does not equate to "If you don't have the anomaly you don't have the #2 present in your clays", without a mechanism. Don't get me wrong, it may be the case I'm just looking for a reasonable rationale that would explain it. At this point I believe the only thing you can state as fact is "If you don't have the anomaly, the deposit has not experienced the conditions that create it", and from there you can speculate, in this case, with all the other variables present, whether that is a bad thing, or a good.
A friendly reminder, in science to prove your position you must attempt to disprove your hypothesis. To all I am not attempting to prove or disprove the commercial viability of this deposit or the degree of its "ionic-ness", I simply do not know that at this stage and await further company data. As always this is opinion and reflection only.
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