Diamond Exploration and Mining | Monday, March 4 | 3:15 - 3:40 pm | Room 716
Exploration for, and development of diamond deposits falls in the high-risk, potentially high-reward sector of the minerals industry, in large part because commercial diamond grades are remarkably variable (0.02 to 10 carats per tonne), as are commercially viable diamond values ($20 to ~ $2,000 per carat average). Successive time-consuming and costly bulk sampling (or trail mining) campaigns are hence typically required to establish the economic viability of primary diamond deposits. Since the early-80’s, petrographic or mantle-derived (indicator) mineral attributes have played a storied role as comparatively inexpensive and flexible proxies that may be applied to estimate the diamond potential of primary deposits on a qualitative or semi-quantitative basis. Another comparatively inexpensive approach involves quantitative assay of sub-commercial “micro”diamonds (in the 0.15 to ~ 1.7 mm size fractions), an activity that has expanded materially by way of industry demand since the early 2000’s. A treasure trove of such diamond size frequency data has become available in the public domain, and the public data set now covers micro-, sub-commercial and commercial-sized diamond recoveries for global exploration-, resource- and mine-stage projects that range in known grade from 0.02 to over 5 carats per tonne. This presentation highlights practical utilization of such industry benchmarks to quantitatively forecast (recoverable) commercial grades from microdiamond sampling results. Some observations will be made regarding errors, liPmitations and sample sizes.
