Take it as given that TREO will be higher in weathered rock than...

Take it as given that TREO will be higher in weathered rock than deeper fresh rock, all things being equal. Monazite is weathering resistant compared to other minerals, so concentrates in weathered rock. Obviously there is variable monazite enrichment all over the place, so deeper drill samples can return higher TREO assays than weathered surface samples. Any small amount of REO in clay (and other RE bearing minerals) is likley unrecoverable and worthless.

Monazite, being relatively resistant to weathering, should report similar NdPr ratios regardless of depth for a given lode/deposit. Again, there will be some natural variability in the monazite grains and sampling/analysis variability, but sooner or later a statistically confident NdPr range and average will emerge. There is variation of NdPr between monazites of different lodes/deposits, gut feeling is higher NdPr correlates with higher TREo grades.

HAS has NdPr grades between 30-35% of TREO avergae across their deposits, but between 25-505 variatin between deposits.

DRE early days is averaging about 30% NdPr in TREO in ironstone ore, less than HAS. DRE Carbonatites are averaging 22% NdPr in TREO so far, a trend I expect will continue along the central carbonatite complex.

KFM are averaging a tight 17.5% NdPr in TREO across a range of rock chips and drill samples. Ealry days but it looks like the Chalba Shear zone area is simply lower NdPr monazite than the Lyons Fault area further east. Every carbonatite complex has it's own chemistry usually, with the chance it might be a Mt Weld, worthless or somewhere in between...