We propose a model for an exhausted upper continental crust. The Crepuscular Earth represents a degraded planet where all resources have been extracted and dispersed, and all fossil fuels have been burned. The starting point of the model of crepuscular crust is the composition given by the geochemist Grigor'ev, which is constrained by the conservation of mass statement between the chemical composition of the crust in terms of elements and in terms of minerals. Additionally, the model is given geological consistence, by introducing a series of assumptions based on geological observations. As a result, the obtained crepuscular crust is composed of the 294 most abundant minerals. Together with the model of exhausted atmosphere and hydrosphere developed in a previous paper, the study will serve as a reference for calculating the exergy of the current mineral capital on Earth and its degradation velocity. (C) 2010 Elsevier Ltd. All rights reserved.