Evaluation of gold deposits—Part 1: review of mineral resource estimation methodology applied to fault- and fracture-related systems

Abstract

Mineral resource estimation is a highly skilled activity that is critical to the successful development and exploitation of any gold deposit. The methods available to the estimator for the determination of local and global grades and tonnages fall into two categories: conventional and geostatistical. Conventional techniques are generally based on weighting, averaging or projection of grade, thickness, etc., to produce a global or local resource. Geostatistical methods are mathematically more complex, less biased and permit global and local estimation through the use of interpolation procedures, which reflect the nature and continuity of the mineralization. The choice of what method to apply must be made in consideration of the deposit geology, grade distribution and sample density. In fault- and fracture-related gold deposits major considerations in resource estimation comprise the deposit geology (including continuity and ore controls) and grade distribution (skewness, nugget effect, continuity, mixed populations, etc.). Selected conventional and geostatistical methods are subjected to a critical review, and deposit characteristics that must be taken into account during estimation are discussed.