Mining Concessions and Asymmetric Information by Jean-Christophe Poudou and Lionel Thomas . We study a concession contract for exploiting an exhaustible resource when a mining firm has private information about its costs. We show that the "traditional" balance between revenue and efficiency, which results in a lower level of production than with symmetric information, is not systematic in this contract. This is due to the specific depletion cost of non-renewable resources.