Please show me a portable pXRF handheld analyzer that can reliably detect 20ppb Au, because the entire gold exploration industry is awaiting that technological breakthrough.
Do you even know what a portable pXRF instrument is, and do you know the size of the detection window that is presented to the sample and how that would work on heterogeneous drill core?
As others have commented - they should stop playing around with their pXRF analyzer at the core yard and take it out in the bush and do some soil samples to generate drill targets or at least use it on semi-homogenized 1m RC drill chips, and not on the surface of coarse-grained drill core. There is a reason for the disclaimer that pXRF results on drill core are pretty much useless/spurious point data and the real results from the lab will be from representative crushed and pulverized half-core samples that will invariably be much lower grade. Think of the inherent sample bias of using a pXRF analyzer of NQ or HQ drill core with a detection window of only about 1cm x 2cm maximum, and explain to me how thats representative of that entire 1m of drill core. Here's a hint - it isnt.
Here is a closeup photo of some typical NQ drill core which is 4.76cm in diameter- and the square in red is the typical detection window of a portable pXRF hand-held instrument from Niton or Olympus. Reading time is usually 30 seconds and nothing outside that window is detected by the instrument. The question is - how many readings along a 1m surface of the drill core would you be happy to take to get a representative result of the entire 1m interval of the drill core? Remember the drill core is also a cylinder.
The geological mineral estimate volumes in the summary logs are probably more accurate than cherry-picked pXRF pointing a tiny sample window at specific sulfide minerals on the surface of the drill core.
