Valuing copper mined from ore deposits

Some of Earth's largest metalliferous ore deposits form in response to thermal fluid circulation through its crust. A large hydrothermal copper deposit recently drilled on the mid-Atlantic ridge, formed episodically over a period of about 50,000 years during a heat flow of similar to 2 W m(-2). The total average energy expended on the formation of this deposit is about 1.5 x 10(18) J, which has a present-day thermal equivalent cost of US$1.4 x 10(9). This equates to a natural production cost of US$33,000/ton copper, about 10-20 times the present market value of copper. Similarly, concentrating trace amounts of copper held in ordinary rocks into deposits of economics significance, using modem mining and smelting processes, would cost about 12-25 times the present-day value of copper. Current market prices for copper thus appear to be significantly undervalued. Based on thermodynamic principles, this result may be used to evaluate cryptic externality cost associated with mineral exploitation. (c) 2005 Published by Elsevier B.V.