Over the past several years there have been a number of ‘new’ selective extraction/partial digestion (SE/PD) methods introduced to the mineral exploration industry. Some of these are truly novel, employing emerging technologies and recent chemical discoveries to digest specific mineral components of geochemical samples. Others represent improved, but recycled, historic approaches that benefit from advanced instrumentation and knowledge to surpass the performance of historic SE/PD techniques. Nowadays, most major commercial geochemical laboratories offer their own versions of a variety of SE/PD approaches, and all claim thattheir versions offer significant exploration advantage over conventional analytical techniques.
However, a significant number of geochemists remain unconvinced regarding the advantage that some of these SE/PD techniques offer. This is due to a large number of factors, including: i) the lack of disclosure of the geochemical procedures involved in the digestions, ii) the lack of knowledge of what is actually being extracted from a sample by these methods, iii) the lack of an adequate number of objective assessments of these techniques in orientation surveys, and iv) the lack of adequate rigorous comparisons of the results of these new techniques with those from conventional (trusted) exploration methods.
The objective of empirical assessment of a new exploration technique is to determine whether the new technique provides exploration advantage over competing, established methods. Exploration performance can be determined using the hypergeometric probability of obtaining a result by chance that is equivalent in performance to the results of an orientation survey testing a new SE/PD method. The lower the hypergeometric probability of a result equivalent to that from an orientation survey, the more likely the exploration method successfully detected the presence of mineralization. This probability is thus a quantitative measure of exploration performance that allows rigorous comparison of conventional andnew exploration techniques. Furthermore, this statistical procedure for assessing exploration performance of new SE/PD techniques provides the objectivity required to evaluate the effectiveness of any new exploration method.