Physical versus economic depletion of a nonrenewable natural resource

The present paper explores the relationship between physical and economic depletion of a nonrenewable natural resource using a decomposition of mining costs akin to the one used in the literature on productivity and technical change. We argue that this decomposition can provide key insights on future availability of nonrenewable natural resources. Using data on slate mining in Galicia (Northern Spain), we provide quantitative evidence of the role played by physical depletion in economic exhaustion but also of the offsetting effects of technical change. Additionally, we provide a measure of the effects on economic depletion of input prices, output, fixed inputs and production scale. Input prices and fixed input misallocation contributes far more to economic depletion than physical depletion while technical change has a remarkable negative contribution to economic depletion. Policy implications are discussed, particularly, the importance of promoting technical change. Keywords: Non-renewable natural resources, Physical depletion, Economic depletion, Mining cost, Slate mining, Technical change, Total Cost Growth decomposition