This talk evaluates the feasibility of using mineral rent information to anticipate trends in long run mineral extraction costs, a procedure termed "rent based forecasting".  The procedure is supported by are formulation of the standard economic theory of exhaustible resources and illustrated in an exercise to "back cast" past coal, copper and oil depletion induced cost trends.  Although the technique is advocated primarily for analysts with access to proprietary mineral extraction cost and property sales data, it may also help economists verify forecasts of extraction costs derived from mineral resource stocks and other data.