Industrial Minerals Reserves and Resources Classification and Evaluation

摘要

The key parts of the definition of a mineral reserve are that it is (a) that part of a deposit that can be recovered and sold (geology, mining, and process engineering), (b) is economically (profitably) extractable (market), and (c) is legally extractable (title and permits), as demonstrated at the time the reserve estimate is made. The classification of mineral reserves and mineral resources from the JORC and similar codes is compared with the SEC's Industry Guide 7, which doesn't recognize the mineral resources categories but does recognize "mineralized material," which is equivalent to the sum of the measured and indicated resources of the JORC and similar codes. The SEC's objection to "resources" stems from the word's similarity to "reserves," the fact that the mining industry's use of these terms is the reverse of common English usage, and that resource estimates allow too much latitude for flights of promotional fancy.rnBecause reserves are net of mining and processing losses and resources are in-situ estimates, they should not be mixed. Further, because initial estimates of deposit size generally exceed the economically recoverable and saleable quantity, often by a substantial amount, resource estimates, particularly those made early in a projects life, may be misleadingly optimistic.rnBoth the JORC and similar codes and Industry Guide 7 share some common assumptions. First, they recognize a "blue sky" boundary, a line beyond which estimates of tonnage and grade are too speculative to meet required degrees of assured existence. However, the location of this boundary varies between classification systems. They also include two assumptions that do not apply to industrial minerals; that geology presents the greatest risk in deposit delineation and evaluation and that if you produce a quantity of product (e.g. an ounce of gold or pound of copper) you can sell it. Internationally, there are differing views about whether reserves are part of or separate from the resource base. Defining the boundaries between the categories of resources and reserves conceptually would appear to be a problematic area. In practice, this is seldom the case.rnThe detail and reliability of the mining, processing, environmental, marketing, and other factors required to support a reserve estimate should be very high. Completed full feasibility (bankable feasibility) or reasonably detailed mine plans covering the extraction of all estimated reserves are required by the SEC. Canadian National Instrument 43-101 has less strict feasibility requirements.