Resource Calculations

The tonnage, or quantity, of the mineralized material in a deposit can be calculated if the volume of the deposit is known. The volume can be measured by the depths and widths of the drill holes, and the distance that there is between them – it is very usual nowadays to make those types of calculations by using computer software which sophisticated that also permits a three-dimensional view of the deposit on screen.

The multiplication of the volume by the average density of the mineralization provides the number of tonnes found in the deposit. Even though this can sound simple, orebodies are very capable of being quite complex; the shape of an orebody is often highly irregular, densities change and grades are often discontinuous.

The grades determined by sampling the drill cores are plotted, and a weighted average of the grades is calculated, giving a resource figure. This estimate gives the tonnage and the grade of the deposit, so far as it is known by drilling. More tonnage can be included by drilling areas that have not been drilled yet, but which extend down the dip and along the strike of the zones which are mineralized.

Resource estimates are classified as “measured” if the geologist is satisfied that the tonnage is reasonably certain and the drill holes are closely spaced; th resource estimates are classified as “indicated” if a considerable amount of drilling has been done, but some presumed mineralized zones are not completely tested; and “inferred” if the estimate is based on information from drill holes that are widely spaced.