Brittleness is considered as one of the important cuttability parameters affecting machine selection, design and performance prediction. A project supported by The Scientific and Technical Research Council of Turkey (TUBITAK) was initiated at the Mining Engineering Department of Technical University of Istanbul for detailed analysis of a brittleness concept developed for assessment of cuttability based on indentation tests. This study described experimental studies for quantification of a set of new brittleness indices that could be used for assessment of rock cuttability. The quantification of these indices was based on force-penetration data generated with indentation tests using several rock samples. The results and observations on the samples after indentation testing verified that these indices characterized chipping characteristics of rocks under indentation action. The calculated indices were also compared with the coarse material percentages obtained from fullscale linear cutting tests performed with a conical cutter. It was shown that the brittleness indices could characterize coarse chip occurrence of the rocks.