Multiple Indicator Kriging

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Multiple Indicator Kriging (MIK) is a more recent advancement on other Mineral Deposit Modelling and Block Model estimation techniqies such as Ordinary Kriging. MIK initially showed promise as a new method that could more accurately estimate overall (global) deposit mineral concentrations or grades. Unfortunately, the technique has not lived up to the promised benefits. Through many reviews and experiment the technique has been demonstrated to be frequently responsible for the over estimatation of the total contained tonnages of mineralized material. This problem has been reported for a range of differnent deposit types including typical precious metals and base metals mineral deposits. The primary reason for the failure of the technique have been demonstrated to be in part or totally due to each of the following deficiencies :

• The use of inherently large block sizes (required for adequate spatially distributed drill-hole and block sample support) does not allow for adequate resolution of geologic geometry ;
• The considerable level of difficulty in generating indicator cut-off variograms for all indicator cut-off grade levels ;
• The failure of being able to determine the appropriate levels of post interpolation "uniform conditioning" support or adjustment for reported block grades; and
• The allocating of probability block proportions for each indicator cut-off levels is very difficult to apply and also verify for accuracy without the use of localized high density sampling.

Conditional Simulation is another new interpolation technique that will largely replace MIK and it is showing great promise as preferred deposit modelling method.