Analyses of the relationship between natural resources and economic development frequently neglect the interdependency between the depletion of one resource and the depletion of other resources. Of particular interest is how energy resource extraction is affected by the depletion of nonfuel minerals due to the important role of energy in upgrading minerals to a useful state. Although this relationship has been described in theoretical terms, there is little detailed empirical support to quantify the relationship between the depletion of mineral and fuel resources, we develop a dynamic model that is based on physical, technological, and economic data. Our analysis quantifies the relationship between the depletion of copper in the United Slates and the depletion of fossil fuel and uranium energy resources stimulated by the increase in demand for refined copper that is forecast for the next 50 years. The model calculates the increase in the energy cost of extracting energy due to the depletion of copper. The results of the model indicate that this feedback is significant. The energy cost of producing a refined ton of copper increases 23% over the 50-year simulation period due to the diminution in ore grade and diminishing returns to technical change. The increase in the energy cost for copper increases the production of fossil and uranium fuels, which diminishes their quality and increases their energy cost.