Abstract
During the spring of 2001 a survey was sent out to a number of gold mines to gather information about sampling and resource/reserve estimation practices in the industry. The survey targeted surface gold mines mining deposits having micron sized gold particles. It contained questions on borehole spacing, sampling and resource/reserve estimation practices in both the exploration stage and the production stage. A total of 50 questionnaires were mailed to surface gold mines in the US, Canada and Australia. Of these only 10 responded for a 20% return rate. Of the 10, 3 responses were from Australia and 7 from the US. One of the responses was from an underground mine, since so few responses were received the relevant portions of the survey returned by the underground mine were included in the results. In general 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.
