Abrasiveness is an important characteristic in excavation and tunneling projects many factors affect abrasiveness. One method for determining the abrasiveness of rocks is the Cerchar test. In this study, the effects of the equivalent quartz content (EQC), point load index (I s50), Slake durability index (Id2), and percentage of water absorption (S) on the Cerchar abrasivity index (CAI)of36 rock samples was evaluated using bivariate and multivariate re-gression analysis. The limestone samples showed mineralogical similarities and only Is50 was a contributing factor to CAI, with a linear correlation. In sandstone, Q, EQC, and Is50 affected CAI. This indicates that mi-neralogical factors in addition to strength affect the level of abrasion in sandstone. The correlation between Q, EQC, and Is50 with the CAIis exponential, implying that there are other con-tributing factors, such as cement type and the degree of ce-mentation, that influence CAI. In metamorphic rock, QandEQC showed a linear correlation with CAI, suggesting that only miner-alogical factors influenced CAI.In intrusive igneous rocks, only EQC affected CAI and the correlation between CAI and EQ Cwas ex-ponential. This indicates that other mineralogical factors, such as interlocking texture, may affect the level of abrasion in these rocks. In igneous and metamorphic rocks, there was no relationship between the strength and CAI, only their mineralogy influenced abrasiveness. Relationships were identified using simple regression analysis between groups of rock.Id2 and S showed no correlation with CAI in any type of rock. Only EQC correlated linearly with the CAI in all types of rock. This indicates that the only appropriate miner-alogical factor for comparison of rock in terms of abrasiveness is EQC. A formula was proposed for calculation of CAI in terms of EQC.

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