... as shown below: Hot-Pressed Diamond Drill Bit matrix and Rock Formation Comparison FormEarth PropertyRockBit Matrix TypeSoftShale, soft sand, ... , Biotite Granite, Plagioclase Diorite, Mixed Gnesiss, Tuff, Rock and other mixed Light Particles.930-32, 33-35Carbide Powder ... Mixed Rock, Granite, Plagioclase Rock, Mixed Diorite, K-feldspar Pegmatite, Peridotite, ...