Author: Mike O’Brien, Senior Principal Consultant, P.Geo., Pr.Sci.Nat.
Most technical reports nowadays are filled with supporting evidence to technical reports. So much so, that if you listen carefully, you can sometimes hear the armies of swath plots groan as they struggle to maintain their places on the pages in competition with herds of semivariogram plots and armadas of log probability plots. Vast forests are being hacked down to provide printing paper for legions of tables of abstruse statistical measures. All designed to convince the informed layman reader, the ‘bloke on the Clapham omnibus’, that he can invest in a project and become the ‘smooth chap in the Maserati’. All fine and well, but how are the sample data selected before they are scrutinized, analyzed and massaged into the mineral resource block models and the voluminous report tables?
All too often, one sees a paragraph in a technical report that goes like this; ‘the wireframe meshes that constrain the high/medium/low/waste domains were supplied by the client’. Then the consultant or QP or CP and/or team of assistants are reputed to have waved magic wands, invoked the gods of geostatistics and after a long and sometimes expensive interval, the ‘Independent Technical Report’ has arrived with a loud thud.
Degree of independence
The rude question is ‘how independent’ is the estimation, if the meshes representing the domains were outside the control of the QP? If the data selection is not correct and reasonable according to the geological environment, voluminous reports, MIK, LUC and all the most advanced techniques will have been applied in vain.
Poor meshing without due consideration of the geology can give erroneous grades and tonnages and a good chance the informed layman will have to hang on to that bus pass a while longer. The statistical analyses are only part of the total mineral resource process and it would be wise to consider the preliminary wire framing process as integral and equally deserving of independence (free the mesh!). Building geological meshes is usually a long process involving judgement and experience and quite often the person who has done the job does not even get a mention in the technical report. For some reason the meshing process is seen as being beneath the pay grade of senior personnel while the estimation often gets the glamour (and many more square metres of report pages).
Not good practice vs. good practice
In my opinion, it is not good practice to use unverified wireframe meshes supplied by a third party as a hunting ground for mineral resources. At the very least some comments from the humble builder of the meshes should be incorporated along the lines of ‘reliance on other experts’ and elementary checks such as backlogging statistics should be tabulated in the report. The latter will give some comfort that at least the meshes segregate the intended sampling information from different geological units.
Even better, the QP can roll up his trousers and step into the dark murky pond of wireframe mesh modelling. (Go on, you know you want to!) It is a really good way to get a feel for a deposit before the voodoo starts and the three letter acronyms start dripping from your lips. If your time is just too valuable to consider engaging in such a laborious process, or if you are just crap at doing it, then how about trying some ‘rapid implicit geological modelling’? I know some people who can help you with that….
About Mike O’Brien
Senior Principal Consultant, P.Geo., Pr.Sci.Nat. ARANZ Geo Limited – Expert Services (formerly QG Consulting)
For three decades Mike has been making a difference to Mineral Resources and mines. On the technical front, he has extensive experience in Mineral Resource estimation and geological modelling. He has managed technical teams to achieve results in mining companies and in consultancies. While the majority of his experience has been in gold deposits, he has expertise in the uranium, base metals and multi-product environment. A qualified geologist and geostatistician, he has been a team member and reviewer of due diligence and feasibility exercises in South Africa, Brazil, Ghana, Namibia, DRC, Russia, Kazakhstan, Uzbekistan, Colombia, Peru and the United States. Specialties: Mineral Resource estimation, geostatistics, Mineral Resource classification, Mineral Resource reporting codes, SAMREC, JORC.
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