Determination of the brittleness of rocks is considered as an important preliminary design tool in different mining applications. The brittleness value is an important rock parameter used in the excavation and drilling of rocks. Schmidt's hardness is an inexpensive and easy-to-use surface hardness measure that is commonly used to determine the mechanical properties of rocks, such as strength, cuttability (linear and circular), and permeability. In this study, the S20 brittleness index values were determined by using NTNU model to determine the brittleness values of the rocks which was developed by Blindheim and Bruland (1998). The aim of this study was to investigate the relationship between the S20 brittleness index and Schmidt hardness (RL) values statistically. For this purpose, Schmidt hardness tests and S20 brittleness index tests on 7 different rock samples with different strength properties were performed. Schmidt hardness test values and S20 brittleness index values were statistically evaluated and correlated with SPSS. As a result of this evaluation, it was determined that there was a strong correlation between Schmidt hardness and S20 brittleness index values.
