... can be used as required.3. Hot-pressed Diamond Drill Bit Hardness and Rock Drillability Grades FormRock Drillability ... quartz and dolomite marble, diopside petrochemical diorite, mixed carbide powder rocks, biotite hornblende anorthosite, pyroxenite through, dolomite marble, ... mixed light particles.930° ~32° , 33° ~35°Carbide powder mixed rock, granite, plagioclase rock, mixed diorite, K-feldspar ...