It is widely known through exploration circles that there is an ongoing debate on whether it is best to explore underground via channel sampling or drill test from the surface. The initial cost differential is arguable when exploring underground. However, when looking at the bigger picture of future mine development, underground works can save the company time and money as it will be utilized for the foundation of the actual mine.
Drill testing is the best method used to determine vein location and structure. When it comes to assessing grade, particularly in common erratic type structures, this is often where it falls short to larger size channel samples. In confirming grades, samples that are twenty five kg/m and above are best in these cases. A surface drill core is only eight kg/m, while underground drill core are smaller nevertheless at three kg/m. Therefore in a nuggety and erratic type vein structure, channel sampling is the best grade control technique for underground vein systems.