El Fuego area Exploration, page-259

PXRF can be useful but comes with a few caveats. 10 years since I saw one and even then didn't really use it.

Some projects they are almost as good as assay data. ALMOST but don't replace.

HCH being a variably disseminated style of Cu dominant mineralisation wouldn't give very reliable PXRF numbers. So you may be correct they don't use them especially for diamond core (Geos should have a pretty fair idea by now).

RC piles could be more homogeneous and perhaps amenable to an average of multiple readings to get an idea of Cu levels and use them to aid in where to site possible additional holes.

Another use of PXRF is to try and work out rock types. Helped a bit with highly altered rocks at my last work site.

I see a lot of new technologies being introduced by the Majors (Rio in particular) that is gradually becoming more reliable and will replace aspects of subjective geos. Still a long way to go to become Spock's tricorder.

['I pity the geos who have to log these altered rocks' paraphrasing a Petrographer's comment after looking at 30 odd thin sections from the site above. Incredible range of rock type interpretations made by geologists led to a PXRF program to do lithogeochemistry on ALL 400+Kms of diamond pulps.]

Many uses for these new fangled machines.....