Partial or total durability characterizes a large class of exhaustible resources. We show that Hotelling's r-percent rule will apply to a durable resource produced in a competitive market, but will not apply if the resource is produced in a monopolistic market. However, the r-percent rule does not mean that price is steadily rising. We show that in general the competitive market price will fall initially as the stock in circulation increases, and later will rise as the stock decreases and eventually depreciates toward zero after production ceases. Accounting for durability may thus help explain the U-shaped long-term price profiles observed for many resources.

David Levhari, Paul A. Samuelson; The Nonswitching Theorem is False, The Quarterly Journal of Economics, Volume 80, Issue 4, 1 November 1966, Pages 518–519

[This paper studies the effect of lifetime uncertainty on optimal consumption decisions. It is shown that for risk averters changing the distribution of lifetime uncertainty decreases consumption due to the higher probability of having a longer life and increases consumption due to the desire for sure consumption in the present. The stronger of these effects determines the effect of lifetime uncertainty on optimal consumption decisions. The major result is that if the utility function is Cobb-Douglas and the rate of return is not too large relative to the amount of future discounting then lifetime uncertainty will always increase consumption.]