Abstract: This disclosure relates to updating an estimate for a material property of a volume, for example, updating the estimate of iron concentration in a block of a mine block model. The estimate is based on values of one or more model parameters. A processor receives a measurement of the material property outside the volume. Then, the processor determines updated values for the one or more model parameters based on the estimate and the measurement and determines an updated estimate for the material property of the volume based on the updated values for the one or more model parameters and the measurement. Since a measurement outside the volume is used to determine updated model parameters and an updated estimate of that volume, the model is more accurate and the estimate for the material property of the volume is also more accurate although measurements within that volume are not available.