CRITICAL PARAMETERS FOR THE PRODUCTION DEPLETION AND SUBSTITUTION OF MINERAL RESOURCES.

From the mining history of different mineral commodities it is indicated that the average annual growth of production can be used as an indicator for their economic and industrial maturity. Calculations show the growth rate to be determined by the size of the remaining reserves as function of the annual production. Its value at all times tends to remain directly proportional to the number of times that a mineral industry could double its annual production before depleting its remaining reserves. The observations indicate logistic growth of mineral production toward a moving ceiling which is determined by both natural- (clarke and specific mineralisability) and technico-economic- (price and current state of mining technology) parameters. If confirmed, this will enable the prediction of ultimate production levels and possible rates of substitution of scarce commodities by more abundant ones. Furthermore, it would increase the physical base for the viability of our technological society by a factor greater than 10; increasing its predictable lifetime from less than a century to well over a thousand years. Using this relation to predict the size of the inferred reserves of a metal from its current annual production and average growth rate, close confirmation of independent estimates with the Mimic model is obtained for the major metals iron, aluminum, copper, gold, zinc and lead, each with a value of annual production in excess of one billion US. Somewhat less convincing results are obtained for the almost equally well established industries of nickel, tin, mercury and antimony. They show lower growth rates than allowed by the theory. Still lower rates are found for the metals chromium, manganese and tungsten. The nonconforming metals all are commodities for which the USA territory shows marked deficiencies.