Combine this with the second batch of Minlab assays on the 1m samples giving below detection (which is also suspect) my conclusion is that contamination and/or lab error of some form has crept in.
The same step change happens between batches of assays for PP011.
Where 10m RC composites range between 10-45 ppm Co from 0-150m (Minlab Ref No. 83/444) and then for 150-240m (Ref. No. 83/466) the first two 10m composite assays are 445 and 340 ppm Co followed by the 80m at ~0.7% Co.
I doubt the drilling process would put in enough Co from even highly abrasive lithologies which these may not be.
Grasping at straws on the drilling end the drillers may have used the wrong type of bit. For soft rock they use bits with diamonds set in a harder matrix and the reverse for hard rocks (diamonds set in a soft matrix that wears away more quickly exposing the diamonds to do the cutting - actually quite a complex art that requires a competent driller with a range of bits).
IMO one of the most likely areas of contamination could have been the diamond saw (if used) cutting done to create the 10m composites. Again the amount that comes off a saw blade is unlikely to give the levels encountered.
Another possibility could have been the type of crushing and pulverising equipment used at the lab. The crushing of a 10m composite could have required different equipment than the later 1m samples at Minlabs.
Other possibilities are drilling chemicals, lubricants in the compositing process, alternating samples from another project, laboratory stuff ups, typo? - transposing say Phosphorous for Cobalt . There may be other possibilities of contamination etc I haven't thought of. Murphy's law - if it can happen it will sooner or later.
None of the above readily explain the chemical patterns seen in the assays. I suspect there is a problem with the batch of high grade assays (Job Ref 83/466) but why there should be an order of magnitude increase down hole to a max of 1.47% Co is mysterious. Riva have given this lots more thought and decided to drill next month.
The results of this drilling will probably not explain why the assay results were conflicting as that is an academic question that while interesting won't matter then. For now:
Low Co in 2017 will indicate contamination or a lab issue of some form happened in 1983 for one batch of assays.
High results will probably mean Minlabs made some major error with the 1m assays and perhaps the boundary between Esso and ACM at 278m in PP009 is a 'by chance?' major geochemical break.
However, what are the chances of this happening in PP011 also? Either a very good or a very bad coincidence.
GLTAH DYOR
RIR Price at posting:
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