Block models generated with all linear interpolation algorithms contain inherent smoothing that typically results in an underestimation of grades and overestimation of tonnes in resource estimates. For mineral deposits that are anticipated to be exploited by underground mining methods excessive smoothing may result in materially misleading estimates of Ore Reserves._x000D_
To account for smoothing in the open pit mining environment recoverable reserve techniques such as indicator kriging and uniform conditioning are employed to provide non-spatially located proportions of the large blocks above the cut-off grade. These models are not suitable for underground mine planning where the actual location of material above cut-off is required to design its extraction._x000D_
To correct for excessive smoothing it is proposed to modify the ordinary kriged block estimates a posteriori using an affine correction with a local variance adjustment factor. The proposed methodology is demonstrated for a base metal deposit during a feasibility study._x000D_
FORMAL CITATION:Richmond, A, Gaze, R and Horton, J, 2009. Desmoothing block models for underground mine design, in Proceedings Seventh International Mining Geology Conference 2009, pp 265-268 (The Australasian Institute of Mining and Metallurgy: Melbourne).