Once the estimations of resources and recoverable reserves have been made, the next step is to plan the mining project itself. This involves choosing mining appliances, type of haulage, requirements of stockpiling and blending, mill planning, etc. Some of these choices are conditional, in all or part, upon the structures of the variabilities of the ore characteristics, either in situ or at any of the various stages of mining, haulage, stockpiling and mill feeding. It will be shown later how geostatistics can be used to provide representations of these variabilities by means of numerical models of the deposit. The effects of various extraction and blending processes can then be tested by simulating them on these numerical models.