<p>There are numerous rock material elements in one zone of the rock mass system that their uniaxial compressive strength (σ_ci) can significantly vary from one element to another. Thus, using σ_ci test results from only one rock element cannot represent the strength of hundreds of rock elements in a specific zone and such an uncertainty regarding the proper assessment of σ_ci has not yet been clarified. In this study, assessment of σ_ci has systematically been investigated to develop an optimized method through the statistical analysis of both the direct measurement and estimating σ_ci by Schmidt hammer rebound (Hs) considering technical and economical subjects. First, σ_ci, porosity, unit weight and Hs of 17 groups of specimens from different rock elements in one zone of Rashakan limestone mine were tested randomly and statistical analysis of variance (ANOVA)—F test showed that 17 groups of results were significantly different and σ_ci varied from 33.00 to 89.35&#xa0;MPa. σ_ci was also estimated by Hs for 17 rock blocks (elements). The scatter of estimated values of σ_ci by Hs and the relevant mean value was similar to direct measured test results. Geological strength index (GSI), parameters of rock failure criterion significantly varied from one group to another regarding σ_ci results of each group for the both methods. However, the grand mean values of the output parameters were the same for the both methods. Whereas, the cost of direct measured σ_ci was 11.7 times greater than the cost of estimated σ_ci by Schmidt hammer rebound. </p>