The focus of this study is to statistically evaluate the correlations between brittleness, destruction specific energy (SEdes), and both cut-ability and drillability using the optimum data obtained from the experimental works. Applying regression analyses, the predictive models of cutting specific energy (SEcut) and the drilling specific energy (SEdrill) were developed based on the rock brittleness and rock destruction energy data. The models were verified by statistical tests and found to be reliable on being used in practical situations. Good linear, polynomial and exponential relationships between SEcut of circular diamond saw blades and the brittleness B-1 (the ratio of compressive strength to tensile strength), B-2 (the ratio of compressive strength minus tensile strength) and B-3 (compressive strength multiple tensile strength divided by two) were found. There are no correlations between SEdrill of polycrystalline diamond compact (PDC) core bits, impregnated diamond both core and non-core bits and brittleness values. The newly defined destruction specific energy (SEdes) was estimated from the area (integral) under stress-strain envelope in unconfined compression test. This method provides a better understanding of the relationships between SEcut, SEdrill, drilling and cutting rate, and the main mechanical rock character. SEdes was found to be directly related to brittleness of B-1, B-2 and B-3. Each method of measuring brittleness has its own usage in rock processing depending on practical utility (C) 2008 Elsevier B.V All rights reserved.