Geostatistical ore-reserve estimation of alluvial gold deposits in Greece

Geostatistics permits the estimation of the values of a variable at every location of a deposit, together with calculation of the estimation errors. Thus, for example, on the basis of an estimation of the ore reserve and the confidence limits of that estimation the outcome of a mining project can be predicted with some certainty. It is almost impossible to calculate such confidence limits by classical evaluation methods. Alluvial deposits are the only type of gold deposit that is being explored at present in Greece. They present peculiarities that relate to the spatial extent of the mineralization, the low grade, the need to excavate and process large volumes of gold-bearing material and the specialized equipment required to recover it. The application of geostatistics aids in determination of the optimum grid for the exploratory boreholes. This enhances the estimation of reserves on a local scale and the calculation of associated confidence limits and helps in the determination of the optimum pit limits.