... below: Hot-Pressed Diamond Drill Bit matrix and Rock Formation Comparison FormEarth PropertyRockBit Matrix TypeSoftShale, soft sand ... Rocks, Amphibolite Granulite, Amphibolite, Biotite Quartz Schist, Angular Rock, Garnet Diopside Skarn, Biotite Dolomite Marble, etc.720, ... Light Particles.930-32, 33-35Carbide Powder Mixed Rock, Granite, Plagioclase Rock, Mixed Diorite, K-feldspar Pegmatite, Peridotite, ...