The degree to which a rock abrades a cutting tool or a bit is called its “abrasivity”. Laboratory tests of abrasivity can be broadly divided into 4 kinds; drilling, rubbing, turning operation and tumbling tests. In the previous study, authors conducted drilling, rubbing and turning operation tests to examine rock abrasivity. Within the range of tests conducted, the turning operation test turned out to be superior to the other tests, albeit slightly, in terms of practicality. The present study was started to compare the results of the turning operation test with those of two scratch tests (Mohs and CERCHAR tests) . Mohs hardness created by Friedrich Mohs is widely known as hardness scale especially for minerals. CERCHAR test developed by Centre d’Études et Recherches des Charbonnages de France is also widely used to examine rock abrasivity especially in France in the coal mining industry. The results of two scratch tests have been investigated and compared with the results of the turning operation test. Comparatively, better correlation was observed between the Mohs hardness and the abrasivity index of the turning operation test. Reasonable correlation was found between the abrasivity indices of the CERCHAR and the turning operation tests. The correlations are applicable within the following range, 2.5 ≤ IMohs ≤ 6.
