By using geostatistical simulation techniques, the spatial prediction of the P-32 and the corresponding measures of uncertainty can be obtained on a block-by-block basis. This methodology is applied to a data set from the El Teniente copper mine, Codelco-Chile. The objective is to map the expected values of the intensity of stockwork veins with a weak infill mineral assemblage and a typical thickness greater than 1 mm, which are referred to as weak veins. Confidence limits on this intensity and its probability of exceeding given critical values are also estimated. The quality of the prediction and of the uncertainty quantification is checked by leave-one-out cross validation. The resulting confidence limits and probability maps can be used as indicators to define geotechnical domains in the rock mass.