- © 2002 Canadian Institute of Mining, Metallurgy and Petroleum
This text consists of two parts, comments on “Classification and Reporting of Mineral Resources for High-Nugget Effect Gold Vein Deposits,” by S.C. Dominy, P.R. Stephenson and A.E. Annels, Volume 10, No. 3, pp. 215-233, and related comments on some features of the JORC Code.
This paper is, in many respects, a very elaborate and valuable account of the problems encountered in the estimation and classification of high-nugget gold deposits. However, in some key areas, it appears to fall short of its objective to help “resolve satisfactorily most issues” and “contribute to improved estimation and classification” (abstract).
One must realize that high-nugget effect gold deposits constitute a very narrow field, despite the occasional bonanzas. This is a field of mostly smaller sized deposits, where limited success and a significantly higher rate of failure occur relative to larger deposits of mostly lower grade. This is shown by the six deposits described in the paper. Thanks for contributing to greater understanding of these complex and nevertheless challenging deposits.
Quality Assurance/Quality Control
It is disappointing that after discussing briefly the quality control of sampling and sample preparation and assaying in its first part, the paper more or less took leave of this subject and only mentioned it incidentally a few times. Moreover, neither the abstract nor the conclusion refer to the need to optimize the validity of these essential data.
That high-nugget deposits are very difficult to sample, assay, appraise, estimate and classify is undisputable. The ranges of variation observed in both the grade and the physical distribution of the mineralization are very high. In high-nugget deposits, this requires larger samples, up to 15 kg or more for wagon or truck samples, and preparation of larger portions for assaying, likely with assaying of sieved metallics (Dominy et al., 2000). Depending on less erratic sampling/assay results and getting …