Literature analysis shows that the physical significance of the equation from which the index B b is calculated does not support its description as the ash basicity index. For quantitative assessment of the coal's mineral component, which has an important influence on the coke quality-specifically, on CSR and CRIthe potential reactivity of coke (CRP) is recommended as a better characterization of the index B b . Three and two parameter versions of the formula for CRP are presented. Models of the relation CRP = f(I b ) are developed for different parameter ranges. It is found that CRP and I b are not analogs. Therefore, in the devel opment of resources for the production of high quality coke (in terms of CRP and CRI), these parameters should both be used.