Significance of Nested Structures in Modeling of Uranium Grade Omni Variogram for Uranium Mineral Deposit

Accurate modeling of omni-directional assay variograms for a deposit, plays a very significant role in the results of 3-D assay estimation and therefore its distribution within the estimation blocks. The high grade variations in uranium deposits render the significance of accurate variogram modeling. By this research, some models have been fitted to the experimental variograms with 0.5 meter composited uranium assay data, resulted from chemical analysis of drill core samples, from a uranium deposit. Reciprocal validation test has been applied for selection and evaluating the effect of suitable results, from multi-structural models in compare with other proper types of models. Validity study of the models is conducted through the reciprocal validation test, based on a series of criteria such as the average of differences and the difference of estimated values and raw data, in order to determine the validity accuracy of the fitted model. It is concluded that the dual-structure spherical model has a higher validity and furthermore reveals the significance of minor structures in variogram modeling, specifically for uranium deposits.