A SURVEY OF SAMPLING AND RESOURCE/RESERVE ESTIMATION PRACTICES IN THE SURFACE GOLD MINING INDUSTRY

Abstract

The survey was sent to 50 surface gold mines in the USA, Canada and Australia and contained questions on borehole spacing, sampling and resource/reserve estimation practices in both the exploration and production stages. Only 10 responded, with 3 from Australia and 7 from the USA One of the responses was from an underground mine, and relevant portions were included in the results. In summary, it was found that inverse distance and geostatistical methods were used the most in calculating resources and reserves in the exploration stage. This was usually done by a team consisting of a geologist, a mining engineer and a metallurgist/geotechnical engineer. In some cases, an outside consultant reviewed the calculated resources/reserves. During production, the polygonal method was most widely used, followed by geostatistical methods. Most mines indicated that duplicate samples were assayed and that statistical analysis was done to check the validity of the sampling and assaying practices during both the exploration and the production stage. The majority of the mines surveyed indicated that a gold content versus particle size distribution study was carried out on the blast hole cuttings.