Grade control plays an essential role in the good running of a mine. The factors at play are many, starting from a good analysis of the geology and a correct sampling procedure._x000D_
Once this is achieved (and it is an essential prerequisite), the problem is to adequately define what is ore and what is waste. This paper tries to show, through a small example, how simple geostatistical techniques (variography, and moving average or kriging), can help in accurately defining these limits in a geologically homogeneous zone, thus allowing optimal use of the available information.