XRF is elemental analyses that gives actual Nickel %, as well as...

XRF is elemental analyses that gives actual Nickel %, as well as a number of other elements, including Iron, Copper, but can't do Gold.
The handheld XRF "guns" give a very quick reading of spot samples across whatever type of sample is being analyzed, including core.
A number of readings from the same spot would all give slight elemental variations because the "window" of the XRF "gun" is so small, and the crystals of minerals are all slightly differently oriented, but typically an average is taken and used.
Long story short, the geos on site can visually differentiate pentlandite from other sulphides and apply a visual estimate (having done it myself for years) and the XRF is just proof of identification. If the visual estimate of pentlandite % is good then a fair assessment can be made of overall nickel % in a volume of core.
Its more about whether you believe a 2" stick of core is representative of a deposit, personally I think its worth the punt. Pentlandite doesn't just "happen".
FYI - Pentlandite is roughly 1/3 Iron, 1/3 Nickel and 1/3 Sulphur. 33% nickel.......pew pew
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