Effect of Phenocrystic Orthoclase Content on Leeb Hardness Values of Granitic Rocks

Abstract

The Leeb hardness (HL) method, which is one of the surface hardness measurement techniques used for materials, has recently gained widespread application in rock mechanics and engineering geology studies. However, limited research has been conducted on the factors influencing HL values. This study aims to investigate the effect of phenocryst-sized minerals on HL values in granitic rocks originating from Türkiye. Within this scope, HL values were determined on 72 surfaces belonging to two different rock types (Kaman Rose and Dusty Rose). Subsequently, high-resolution images obtained from each sample surface were evaluated using image analysis techniques, and the orthoclase mineral percentage (OMP) on the surfaces was quantitatively determined. The relationships between HL and OMP values obtained from the cube sample surfaces of both rock groups were investigated through simple regression analysis, and strong positive linear correlations were identified. The OMP value on the sample surface was determined to be a decisive parameter directly influencing the HL values of the rocks. Textural heterogeneities caused by phenocrysts influenced the HL test results, thereby limiting the applicability of the method to such rock types.