The guide to the evaluation of gold deposits: integrating deposit evaluation and reserve inventory practices

CIM Bulletin, Vol. 85, No. 957, 1992

Marcel Vallee, Geoconseil Marcel Vallee inc., Sainte-Foy, Quebec, and Denis Cote, ROCHE Ltd., Consulting Group, Sainte-Foy, Quebec

The Guide to the Evaluation of Gold Deposits reviews the successive evaluation steps in the domains of geology, engineering, and economics. The Guide analyzes, in a systemic perspective, the sequence of exploration, development, and evaluation work required to bring a mineral deposit to production. The aim is to identify the metal/mineralization losses and ore dilution that each work step contributes to the evaluation and mining process. The procedure allows one to maximize the income and profits of a mining operation, and to reduce the risks of financial losses tied to investment decisions in the mining sector. For greater efficiency, the criteria of reserve estimation and classification should be integrated with the evaluation steps and methods. At earlier stages of deposit development, when quantitative knowledge is available mainly on the geological axis, the term "delimited mineral deposit" should be used. The term "reserve" should be used only in an operating mine or in a mining project, when information in the geological, engineering, and economic domains is adequate to ensure technical and financial feasibility. "Reserves" are by definition "mining reserves". Each category of proven/probable reserves and measured/indicated deposits should be subdivided into two classes to express better the many steps of mineral valuation. The category of "possible reserves" shall be replaced by that of "inferred mineralization". This system, derived from the Australasian Code, can easily be integrated into current practices of the exploration and mining industry within a short timeframe. The proposal to develop the use of the margins of error of the estimates at a confidence level of 90% should be viewed in a longer timeframe. Establishing the precision of the mineral inventories and distinguishing between categories and classes by means of the margin of error will require more work and a longer break-in period.
Mots Clés: Exploration, Gold deposits.