LETTER TO THE EDITOR — The evolution of geostatistics

Jim Whyte’s recent article (“Recent history reveals trends in mine failures”, T.N.M., Sept. 28-Oct. 4/98) was an interesting read, even more so when I came across my name and quotes from a 1991 article in The Northern Miner Magazine. The article in question was a summary of a paper I gave at the 1990 annual general meeting of the Canadian Institute of Mining, Metallurgy and Petroleum on behalf of my employer at the time, Strathcona Mineral Services. It makes interesting reading to go back and look at nearly ten-year-old thoughts and reflect on changes since then.

The comments at the time were the result of observations made during an early period in the evolution of the widespread use and practice of geostatistical reserve estimation. Certainly geostatistics has been around a long time, and very successfully applied in certain situations. However, with the proliferation of desktop computers and the development of more software, the use and misapplication of the method increased. My point at the time was that untrained and inexperienced people were using the method without really understanding what was going on, and that the true experts were intimidated by the new techniques and did little to question their validity.

Ore reserve calculation involves both quantitative and qualitative assessments. Geostatistical methods certainly look after the former, but the latter remains a judgment call and is easily overlooked when one is banging away on the computer. The “art” which goes into an estimation (which can only be gained by experience) can be pushed aside by “science”. Today’s discussion of the requirement for a “Competent Person” to oversee reserve estimation is the regulator’s way of trying to ensure the “art” does not take a back seat.

Ten years later, are things different? Without question, yes. We have many practitioners now with a great deal of experience, excellent software which is much more user friendly, and, most importantly, many examples from which to learn what can go wrong.

Geostatistical reserve estimation has rightly assumed a dominant place in our arsenal of project evaluation tools, along with the widespread knowledge of when it can and cannot be relied upon.

Graham Clow

President

Manhattan Minerals

Vancouver, B.C.