can this continue?, page-42

gosouth,

My reasoning lies in the sizing and homogeneity of the sample being analyzed.

1) Depth of penetration of the XRF gun is ~ 2-5mm depending on the medium.
2) Analyzer window is about the size of the 5 cent piece
3) The sample is most likely very heterogeneous due to the ore being massive/ semi-massive in nature.

Let's take a standard 1 meter interval of NQ core, the radius of the NQ core is 3 cm or 2827 cm^3 of volume ( pie x R squared x height)

Lets assume the XRF could penetrate to 5mm and that we XRFed 100% of the surface area of the 1 meter core minus the top and bottom face, using the same calculation, the volume analyzed would be 78.5 cm^3 out of the 2827 cm^3 of core. (max 2.8% of the core can be analyzed by the XRF assuming 100% coverage of the 1m core)

Now to cover 100% of the diamond core ( surface area 1885 cm^2) with the 5 cent sized analyzer (surface area 12.6 cm^2) we would need to take about 150 zaps per meter of core. (Not very efficient way to do this since each zap is about 60-90 seconds).

So even with zapping the 6m intersection 900 times for 100% coverage of the core, we would only get to analyze a max 2.8% of the total sample volume. (Not very good for heterogeneous sample)

The heterogeneity of the sample makes it even harder to correctly analyze diamond core. What's in the 97.2% of the rock not analyzed? Is it sulphides ( I hope so) but until the core is smashed, crushed and pulverized, we can't be sure.

Therefore, the best way to effectively do an XRF reading of diamond core is to prep the samples so it's homogeneous and then take multiple readings for an average.

I agree, no companies should be announcing XRF rockchip results for the same reasoning above.

I agree, it is likely someone XRF the core and found them to be nickel bearing but they cannot be certain of the grade ( for the reasons above) so therefore they are not reported.

I think if ROX did XRF the core, they should have released whether the sulphide encountered is nickel bearing. As for the grade, I believe they will have to be from the lab.


Cheers,
fly