Variography Clause Samples

Variography. The degree of spatial variability in a mineral deposit depends on both the distance and direction between points of comparison. Typically, the variability between samples increases as the distance between samples also increases. If the degree of variability is related to the direction of comparison, then the deposit is said to exhibit anisotropic tendencies which can be summarized with the search ellipse. The semi-variogram is a common function used to measure the spatial variability within a deposit. The components of the variogram include the nugget, sill and range. Often, samples compared over very short distances (even samples compared from the same location) show some degree of variability. As a result, the curve of the variogram often begins at some point on the y-axis above the origin - this point is called the “nugget”. The nugget is a measure of not only the natural variability of the data over very short distances but also a measure of the variability that can be introduced due to errors during sample collection, preparation and assaying. The degree of variability between samples typically increases as the distance between the samples becomes greater. Eventually, the degree of variability between samples reaches a maximum value. This is called the “sill” and the distance between samples at which this occurs is referred to as the “range”. The spatial evaluation of the data in this report has been conducted using a correlogram rather than the traditional variogram. The correlogram is normalized to the variance of the data and is less sensitive to outlier values, generally giving better results. Correlograms have been produced from the 5-foot composite drill-hole sample data for the CX HG and Range Front HG domains using the commercial software program Sage 2001 (I▇▇▇▇▇ and Co). Multidirectional correlograms were generated at 30o intervals both horizontally and vertically resulting in a total of 37 sample correlograms in which an algorithm determines the best-fit model. The sample correlograms are included as Appendix 17-1 (CX Correlogram) and Appendix 17-2 (Range Front Correlogram), and are summarized in Table 17-5.